/* ==========================================================================
   Echo 官网 · 设计系统
   --------------------------------------------------------------------------
   母题：回声 / 涟漪。色相锚点 264°（取自 LOGO 电光靛 #5484ee），
   全站只用这一个紫色家族，靠明度与彩度分层，不做多色霓虹。
   ========================================================================== */

/* ---------------------------------------------------------------- 字体 */
@font-face {
  font-family: "LXGW WenKai";
  /* 版本号必须与页面里的 preload 一致，否则浏览器会把它当两个资源重复下载 */
  src: url("../font/lxgw-wenkai-subset.woff2?v=36ab8c12") format("woff2");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
  /* 子集化字体：只含站内实际用字，约 190KB */
}

/* ---------------------------------------------------------------- Tokens */
:root {
  /* 系统字体栈：教程这类"读文档"场景使用——字号小、字重层次多，屏幕可读性优于楷体 */
  --font-system: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue",
    "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", sans-serif;

  /* 楷体栈：全站默认（品牌语调） */
  --font-kai: "LXGW WenKai", "LXGW WenKai GB", "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", "Source Han Sans SC", system-ui, -apple-system, sans-serif;

  /* 表面：蓝黑底 → 逐层抬升，色相始终围绕 264° */
  --bg: oklch(0.180 0.030 268);
  --bg-deep: oklch(0.140 0.028 270);
  --bg-void: oklch(0.115 0.025 272);
  --surface: oklch(0.225 0.034 270);
  --surface-2: oklch(0.262 0.036 270);
  --surface-3: oklch(0.305 0.038 269);

  /* 描边：极轻，靠明度差而非阴影分隔 */
  --line: oklch(1 0 0 / 0.08);
  --line-strong: oklch(1 0 0 / 0.14);
  --line-accent: oklch(0.632 0.168 264 / 0.40);

  /* 墨色：浅字在深底上显得更轻，故正文不提纯到纯白，靠行高补 */
  --ink: oklch(0.966 0.006 268);
  --ink-2: oklch(0.878 0.014 270);
  --muted: oklch(0.792 0.022 269);
  --muted-2: oklch(0.672 0.028 268);

  /* 品牌色 */
  --accent: oklch(0.632 0.168 264);
  --accent-bright: oklch(0.718 0.158 262);
  --violet: oklch(0.691 0.143 300);
  --glow: oklch(0.815 0.079 309);

  --focus: oklch(0.762 0.142 264);

  /* 语义 */
  --ok: oklch(0.782 0.132 158);
  --ok-bg: oklch(0.782 0.132 158 / 0.12);
  --warn: oklch(0.822 0.140 82);
  --warn-bg: oklch(0.822 0.140 82 / 0.12);
  --bad: oklch(0.688 0.176 22);
  --bad-bg: oklch(0.688 0.176 22 / 0.12);

  /* 版面 */
  --container: 1240px;
  --gutter: clamp(1.25rem, 4vw, 2.5rem);
  --radius: 14px;
  --radius-sm: 10px;
  --radius-pill: 999px;

  /* 竖向节奏 */
  --space-2xs: 0.375rem;
  --space-xs: 0.625rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2.25rem;
  --space-xl: clamp(2.75rem, 6vw, 4.5rem);
  --space-2xl: clamp(4rem, 10vw, 8rem);
  --section-y: clamp(3.5rem, 8vw, 7rem);

  /* 运动：全部出场曲线 */
  --ease-quart: cubic-bezier(0.25, 1, 0.5, 1);
  --ease-expo: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-soft: cubic-bezier(0.4, 0, 0.2, 1);
  --t-fast: 160ms;
  --t-base: 280ms;
  --t-slow: 620ms;
  --t-reveal: 900ms;

  --shadow-lift: 0 18px 44px -22px oklch(0.10 0.04 270 / 0.9);
  --shadow-window: 0 34px 90px -30px oklch(0.08 0.05 272 / 0.95);

  /* 层级：语义化，禁止 999 */
  --z-base: 0;
  --z-canvas: -1;
  --z-sticky: 40;
  --z-overlay: 60;
  --z-modal: 70;
  --z-toast: 90;
}

/* ---------------------------------------------------------------- Reset */
*,
*::before,
*::after { box-sizing: border-box; }

* { margin: 0; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 88px;
}

body {
  min-height: 100dvh;
  background: var(--bg-void);
  color: var(--ink-2);
  font-family: var(--font-kai);
  font-size: clamp(1rem, 0.96rem + 0.2vw, 1.0625rem);
  line-height: 1.78;
  letter-spacing: 0.012em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

/* 页面可通过 <html data-font="system"> 整体切到系统字体（教程页使用） */
html.use-system-font body,
html.use-system-font .display,
html.use-system-font .h2,
html.use-system-font .h3,
html.use-system-font h1,
html.use-system-font h2,
html.use-system-font h3,
html.use-system-font h4,
html.use-system-font .quote,
html.use-system-font .lede {
  font-family: var(--font-system);
  letter-spacing: 0;
  line-height: 1.7;
}

img,
svg,
canvas,
video { display: block; max-width: 100%; }

/* 安全网：任何内联 svg 都不得失控放大。缺少尺寸类的图标默认按 1em 渲染，
   具体尺寸由各组件规则覆盖。这条规则是为了杜绝"漏掉一个 class 就撑成
   240×240"这类事故再次发生。 */
svg { width: 1em; height: 1em; flex: 0 0 auto; }

img { height: auto; }

button,
input,
select,
textarea { font: inherit; color: inherit; }

button { background: none; border: 0; cursor: pointer; }

a { color: inherit; text-decoration: none; }

ul,
ol { list-style: none; padding: 0; }

:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 3px;
  border-radius: 4px;
}

::selection {
  background: oklch(0.632 0.168 264 / 0.34);
  color: var(--ink);
}

/* 滚动条（桌面） */
@media (pointer: fine) {
  ::-webkit-scrollbar { width: 10px; height: 10px; }
  ::-webkit-scrollbar-track { background: var(--bg-deep); }
  ::-webkit-scrollbar-thumb {
    background: oklch(0.40 0.04 270);
    border-radius: var(--radius-pill);
    border: 2px solid var(--bg-deep);
  }
  ::-webkit-scrollbar-thumb:hover { background: oklch(0.50 0.06 268); }
}

/* ---------------------------------------------------------------- 排版 */
h1, h2, h3, h4 {
  color: var(--ink);
  font-weight: 400;
  line-height: 1.24;
  text-wrap: balance;
}

p { text-wrap: pretty; }

.display {
  font-size: clamp(2.6rem, 1.2rem + 5.4vw, 5.5rem);
  line-height: 1.06;
  letter-spacing: -0.022em;
}

.h2 {
  font-size: clamp(1.65rem, 1.1rem + 2.1vw, 2.6rem);
  line-height: 1.28;
  letter-spacing: -0.012em;
}

.h3 {
  font-size: clamp(1.15rem, 1rem + 0.6vw, 1.4rem);
  letter-spacing: 0;
}

.lede {
  font-size: clamp(1.02rem, 0.98rem + 0.34vw, 1.22rem);
  color: var(--muted);
  line-height: 1.85;
  max-width: 46ch;
}

.body-sm { font-size: 0.9375rem; line-height: 1.75; }

.ink { color: var(--ink); }
.muted { color: var(--muted); }
.muted-2 { color: var(--muted-2); font-size: 0.875rem; }
.accent-text { color: var(--accent-bright); }

/* 手写体语气：用于引语 */
.quote {
  font-size: clamp(1.05rem, 0.98rem + 0.5vw, 1.3rem);
  color: var(--ink-2);
  line-height: 1.9;
}

/* ---------------------------------------------------------------- 布局 */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.container--narrow { max-width: 820px; }
.container--wide { max-width: 1340px; }

.section { padding-block: var(--section-y); position: relative; }

.section--tint { background: var(--bg-deep); }
.section--void { background: var(--bg-void); }

.stack > * + * { margin-top: var(--space-md); }
.stack-lg > * + * { margin-top: var(--space-lg); }
.stack-sm > * + * { margin-top: var(--space-sm); }

/* 区块标题：不用小号全大写眉标签，用一条 1px 短线 + 正文句子 */
.sec-head { max-width: 62ch; }

.sec-head__title { margin-top: var(--space-sm); }

.sec-head__note {
  margin-top: var(--space-sm);
  color: var(--muted);
  max-width: 52ch;
}

.rule {
  width: 40px;
  height: 1px;
  background: var(--line-accent);
  border: 0;
}

/* ---------------------------------------------------------------- 涟漪背景 */
.ripple-field {
  position: absolute;
  inset: 0;
  overflow: hidden;
  z-index: var(--z-canvas);
  pointer-events: none;
  contain: strict;
}

.ripple-field__canvas { width: 100%; height: 100%; display: block; opacity: 0; }

/* 无 JS / 减少动效时：静态辉光层 */
.ripple-field::after {
  content: "";
  position: absolute;
  inset: -20% -10% auto -10%;
  height: 90%;
  background:
    radial-gradient(46% 60% at 78% 8%, oklch(0.632 0.168 264 / 0.30), transparent 70%),
    radial-gradient(38% 52% at 12% 22%, oklch(0.691 0.143 300 / 0.20), transparent 72%);
  filter: blur(20px);
}

/* ---------------------------------------------------------------- 顶栏 */
.nav {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  transition: background-color var(--t-base) var(--ease-soft),
    border-color var(--t-base) var(--ease-soft), backdrop-filter var(--t-base) var(--ease-soft);
  border-bottom: 1px solid transparent;
}

.nav--stuck {
  background: oklch(0.14 0.028 270 / 0.82);
  backdrop-filter: saturate(140%) blur(14px);
  -webkit-backdrop-filter: saturate(140%) blur(14px);
  border-bottom-color: var(--line);
}

.nav__inner {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  min-height: 68px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--ink);
  font-size: 1.125rem;
  letter-spacing: 0.01em;
  flex: 0 0 auto;
}

.brand__mark {
  width: 30px;
  height: 30px;
  filter: drop-shadow(0 0 10px oklch(0.632 0.168 264 / 0.55));
  transition: transform var(--t-slow) var(--ease-expo);
}

.brand:hover .brand__mark { transform: rotate(-8deg) scale(1.06); }

.brand__word { display: flex; align-items: baseline; gap: 0.4rem; }

.brand__en { font-size: 1.06rem; letter-spacing: 0.02em; }

.brand__cn { font-size: 0.82rem; color: var(--muted-2); }

.nav__links {
  display: flex;
  align-items: center;
  gap: clamp(0.4rem, 1.6vw, 1.1rem);
  margin-inline: auto;
}

.nav__link {
  position: relative;
  padding: 0.5rem 0.7rem;
  color: var(--muted);
  font-size: 0.9375rem;
  border-radius: var(--radius-sm);
  transition: color var(--t-fast) var(--ease-soft);
}

.nav__link::after {
  content: "";
  position: absolute;
  left: 0.7rem;
  right: 0.7rem;
  bottom: 0.28rem;
  height: 1px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--t-base) var(--ease-quart);
}

.nav__link:hover,
.nav__link[aria-current="page"] { color: var(--ink); }

.nav__link:hover::after,
.nav__link[aria-current="page"]::after { transform: scaleX(1); }

.nav__cta { flex: 0 0 auto; }

.nav__toggle {
  display: none;
  width: 44px;
  height: 44px;
  margin-left: auto;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  color: var(--ink);
}

.nav__toggle span {
  position: relative;
  width: 17px;
  height: 1px;
  background: currentColor;
  transition: background-color var(--t-fast);
}

.nav__toggle span::before,
.nav__toggle span::after {
  content: "";
  position: absolute;
  left: 0;
  width: 17px;
  height: 1px;
  background: currentColor;
  transition: transform var(--t-base) var(--ease-quart);
}

.nav__toggle span::before { top: -5px; }
.nav__toggle span::after { top: 5px; }

.nav__toggle[aria-expanded="true"] span { background: transparent; }
.nav__toggle[aria-expanded="true"] span::before { transform: translateY(5px) rotate(45deg); }
.nav__toggle[aria-expanded="true"] span::after { transform: translateY(-5px) rotate(-45deg); }

@media (max-width: 860px) {
  .nav__links,
  .nav__cta { display: none; }
  .nav__toggle { display: inline-flex; }

  /* 抽屉展开时才显示：不加 [hidden] 规则会让 hidden 属性被 display:block 覆盖 */
  .nav__drawer[hidden] { display: none; }

  .nav__drawer {
    display: block;
    position: fixed;
    inset: 68px 0 auto 0;
    max-height: calc(100dvh - 68px);
    overflow-y: auto;
    background: oklch(0.145 0.028 270 / 0.97);
    backdrop-filter: blur(18px) saturate(150%);
    -webkit-backdrop-filter: blur(18px) saturate(150%);
    border-bottom: 1px solid var(--line);
    padding: var(--space-sm) var(--gutter) var(--space-md);
    transform-origin: top;
    box-shadow: var(--shadow-lift);
    animation: drawer-in var(--t-base) var(--ease-quart) both;
  }

  .nav__drawer a {
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: 48px;
    padding: 0.85rem 0.25rem;
    color: var(--ink-2);
    border-bottom: 1px solid var(--line);
  }

  .nav__drawer a:last-of-type { border-bottom: 0; }
  .nav__drawer .btn { width: 100%; justify-content: center; margin-top: var(--space-sm); }

  /* 抽屉内的显式关闭按钮（44px 触控热区） */
  .nav__drawer-close {
    position: absolute;
    top: 0.6rem;
    right: var(--gutter);
    width: 44px;
    height: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--line);
    border-radius: var(--radius-sm);
    color: var(--ink);
    background: oklch(1 0 0 / 0.04);
  }

  .nav__drawer-close .btn__icon { width: 17px; height: 17px; }
}

/* 桌面端永远不显示抽屉，即使 hidden 属性被移除 */
@media (min-width: 861px) {
  .nav__drawer { display: none !important; }
}

@keyframes drawer-in {
  from { opacity: 0; transform: translateY(-8px) scaleY(0.98); }
  to { opacity: 1; transform: none; }
}

/* ---------------------------------------------------------------- 按钮 */
.btn {
  --btn-bg: transparent;
  --btn-fg: var(--ink);
  --btn-line: var(--line-strong);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.55rem;
  min-height: 44px;
  padding: 0.66rem 1.15rem;
  border: 1px solid var(--btn-line);
  border-radius: var(--radius-pill);
  background: var(--btn-bg);
  color: var(--btn-fg);
  font-size: 0.9375rem;
  letter-spacing: 0.01em;
  white-space: nowrap;
  transition: transform var(--t-fast) var(--ease-quart),
    background-color var(--t-base) var(--ease-soft), border-color var(--t-base) var(--ease-soft),
    color var(--t-base) var(--ease-soft), box-shadow var(--t-base) var(--ease-soft);
}

.btn:active { transform: translateY(1px); }

.btn--primary {
  --btn-bg: var(--accent);
  --btn-fg: oklch(0.99 0.005 264);
  --btn-line: oklch(0.72 0.16 264);
  position: relative;
  overflow: hidden;
  isolation: isolate;
}

/* 主按钮：点击处扩散的涟漪，作为"回声"母题的交互落点 */
.btn--primary::after {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(
    circle at var(--rx, 50%) var(--ry, 50%),
    oklch(0.95 0.06 300 / 0.5),
    transparent 60%
  );
  opacity: 0;
  transition: opacity var(--t-slow) var(--ease-quart);
  z-index: -1;
}

.btn--primary:hover::after { opacity: 1; }

.btn--primary:hover {
  background: var(--accent-bright);
  border-color: oklch(0.80 0.13 264);
}

.btn--ghost { --btn-bg: oklch(1 0 0 / 0.04); }

.btn--ghost:hover {
  --btn-bg: oklch(1 0 0 / 0.08);
  --btn-line: var(--line-strong);
  color: var(--ink);
}

.btn--quiet {
  --btn-line: transparent;
  color: var(--muted);
  padding-inline: 0.5rem;
  min-height: 40px;
}

.btn--quiet:hover { color: var(--ink); }

.btn--block { width: 100%; }

.btn--sm { min-height: 38px; padding: 0.45rem 0.85rem; font-size: 0.875rem; }

.btn[disabled],
.btn[aria-disabled="true"] {
  --btn-bg: oklch(1 0 0 / 0.05);
  --btn-fg: var(--muted-2);
  --btn-line: var(--line);
  cursor: not-allowed;
}

.btn[disabled]:active { transform: none; }

.btn__icon { width: 17px; height: 17px; flex: 0 0 auto; }

/* ---------------------------------------------------------------- Hero */
.hero {
  position: relative;
  padding-top: clamp(2.5rem, 6vw, 5rem);
  padding-bottom: clamp(3rem, 8vw, 6rem);
  overflow: hidden;
  isolation: isolate;
}

.hero__grid {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1.06fr) minmax(0, 0.94fr);
  gap: clamp(1.5rem, 4vw, 3.5rem);
  align-items: center;
}

/* 竖排引语，桌面端贴在左上角，像书页边注 */
.hero__margin-note {
  position: absolute;
  top: clamp(1rem, 5vw, 3.5rem);
  right: 0;
  writing-mode: vertical-rl;
  font-size: 0.9375rem;
  line-height: 2.1;
  letter-spacing: 0.14em;
  color: var(--muted-2);
  opacity: 0.85;
}

.hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.3rem 0.7rem 0.3rem 0.4rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  font-size: 0.8125rem;
  color: var(--muted);
}

.hero__eyebrow b {
  font-weight: 400;
  color: var(--ink);
  padding: 0.08rem 0.5rem;
  border-radius: var(--radius-pill);
  background: oklch(0.632 0.168 264 / 0.18);
}

.hero__title { margin-top: var(--space-md); }

.hero__title-en {
  display: block;
  letter-spacing: -0.028em;
}

.hero__title-cn {
  display: block;
  margin-top: 0.35em;
  font-size: 0.62em;
  letter-spacing: 0.005em;
  color: var(--ink-2);
}

.hero__desc {
  margin-top: var(--space-md);
  max-width: 44ch;
  color: var(--muted);
}

.hero__desc strong { color: var(--ink-2); font-weight: 400; }

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.7rem;
  margin-top: var(--space-lg);
}

.hero__meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem 1rem;
  margin-top: var(--space-md);
  font-size: 0.8125rem;
  color: var(--muted-2);
}

.hero__meta .dot {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--ok);
  box-shadow: 0 0 0 3px var(--ok-bg);
}

.hero__art {
  position: relative;
  display: grid;
  place-items: center;
  min-height: clamp(280px, 34vw, 460px);
}

/* 声波光球：LOGO + 同心光环 + 呼吸辉光 */
.orb {
  position: relative;
  width: min(100%, 430px);
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  will-change: transform;
}

.orb__img {
  width: 74%;
  filter: drop-shadow(0 0 34px oklch(0.632 0.168 264 / 0.55))
    drop-shadow(0 0 80px oklch(0.691 0.143 300 / 0.35));
  animation: orb-breathe 9s var(--ease-soft) infinite;
}

@keyframes orb-breathe {
  0%, 100% { transform: translateY(0) scale(1); }
  50% { transform: translateY(-10px) scale(1.018); }
}

/* 同心涟漪环 */
.orb__rings {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
}

.orb__ring {
  position: absolute;
  width: 62%;
  aspect-ratio: 1;
  border: 1px solid oklch(0.72 0.14 282 / 0.30);
  border-radius: 50%;
  animation: ring-out 6.4s var(--ease-quart) infinite;
}

.orb__ring:nth-child(2) { animation-delay: 1.6s; }
.orb__ring:nth-child(3) { animation-delay: 3.2s; }
.orb__ring:nth-child(4) { animation-delay: 4.8s; }

@keyframes ring-out {
  0% { transform: scale(0.86); opacity: 0; }
  18% { opacity: 0.9; }
  100% { transform: scale(1.85); opacity: 0; }
}

/* 声波柱 */
.orb__wave {
  position: absolute;
  display: flex;
  align-items: center;
  gap: 4px;
  opacity: 0.9;
}

.orb__wave i {
  width: 3px;
  border-radius: 3px;
  background: linear-gradient(180deg, var(--glow), var(--accent));
  animation: wave-pulse 1.9s var(--ease-soft) infinite;
}

.orb__wave i:nth-child(1) { height: 14px; animation-delay: 0s; }
.orb__wave i:nth-child(2) { height: 26px; animation-delay: 0.15s; }
.orb__wave i:nth-child(3) { height: 40px; animation-delay: 0.3s; }
.orb__wave i:nth-child(4) { height: 24px; animation-delay: 0.45s; }
.orb__wave i:nth-child(5) { height: 16px; animation-delay: 0.6s; }

@keyframes wave-pulse {
  0%, 100% { transform: scaleY(0.55); opacity: 0.55; }
  50% { transform: scaleY(1); opacity: 1; }
}

@media (max-width: 900px) {
  .hero { padding-top: 1.75rem; padding-bottom: 2.5rem; }
  .hero__grid { grid-template-columns: 1fr; gap: 0.75rem; }
  .hero__art { order: -1; min-height: 0; margin-bottom: 0; }
  .orb { width: min(54vw, 230px); }
  .hero__margin-note { display: none; }
  .hero__title { margin-top: 1rem; }
  .hero__desc { margin-top: 0.9rem; }
  .hero__actions { margin-top: 1.5rem; }
  .hero__meta { margin-top: 1rem; }
  .grid-hair { margin-top: var(--space-lg); }
}

@media (max-width: 380px) {
  .orb { width: min(50vw, 200px); }
  .hero__title { margin-top: 0.75rem; }
}

/* ---------------------------------------------------------------- 特性栅格（细线分隔，非卡片墙） */
.grid-hair {
  display: grid;
  /* 4 个条目固定 2×2：平衡、无孤行、每行约 40 字，任何桌面宽度下都不会挤成窄栏 */
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: var(--space-xl);
  border-top: 1px solid var(--line);
}

.grid-hair__cell {
  padding: clamp(1.3rem, 2.2vw, 1.8rem) clamp(1.2rem, 2.6vw, 2.25rem) clamp(1.3rem, 2.2vw, 1.8rem) 0;
  border-left: 1px solid var(--line);
}

/* 2×2：每行第一项贴左；第 3 项起换行并补顶部细线 */
.grid-hair__cell:nth-child(odd) { border-left: 0; padding-left: 0; }
.grid-hair__cell:nth-child(n + 3) { border-top: 1px solid var(--line); }

/* 第二行缩短下边距，避免尾部留白过多 */
.grid-hair__cell:nth-child(n + 3) { padding-bottom: 0.6rem; }

/* 说明：这里刻意不做"超宽屏铺成 4 列"。
   4 个条目排成 1×4 时每列只有约 17 字/行、文字紧贴分隔线，
   在 1920 这类宽屏上观感明显更差；2×2 在任何桌面宽度下都更平衡。 */

@media (max-width: 560px) {
  .grid-hair { grid-template-columns: 1fr; }
  .grid-hair__cell {
    border-left: 0;
    padding-left: 0;
    padding-right: 0;
  }
  .grid-hair__cell + .grid-hair__cell { border-top: 1px solid var(--line); }
  .grid-hair__cell:nth-child(n + 3) { border-top: 1px solid var(--line); }
}

.feature__icon {
  width: 34px;
  height: 34px;
  color: var(--accent-bright);
  opacity: 0.92;
}

.feature__title {
  margin-top: var(--space-sm);
  font-size: 1.0625rem;
  color: var(--ink);
}

.feature__text {
  margin-top: 0.5rem;
  font-size: 0.9375rem;
  color: var(--muted);
  line-height: 1.78;
}

/* ---------------------------------------------------------------- 界面预览 */
.preview {
  display: grid;
  grid-template-columns: minmax(0, 0.86fr) minmax(0, 1.14fr);
  gap: clamp(2rem, 5vw, 4rem);
  align-items: center;
}

@media (max-width: 980px) {
  .preview { grid-template-columns: 1fr; gap: var(--space-xl); }
}

.preview__copy .lede { max-width: 40ch; }

.preview__list {
  margin-top: var(--space-lg);
  display: grid;
  gap: 0.75rem;
}

.preview__list li {
  display: flex;
  gap: 0.7rem;
  align-items: flex-start;
  font-size: 0.9375rem;
  color: var(--muted);
}

.preview__list svg {
  width: 18px;
  height: 18px;
  flex: 0 0 auto;
  margin-top: 0.32rem;
  color: var(--accent-bright);
}

/* 界面展示：真实截图置于辉光之上，不用浏览器 chrome 假装 */
.preview__stage {
  position: relative;
  padding: clamp(1rem, 3vw, 2.5rem);
}

.preview__stage::before {
  content: "";
  position: absolute;
  inset: 8% 4% 12% 8%;
  background: radial-gradient(
    58% 62% at 62% 40%,
    oklch(0.632 0.168 264 / 0.42),
    transparent 72%
  );
  filter: blur(52px);
  z-index: 0;
}

.preview__window {
  position: relative;
  z-index: 1;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-deep);
  box-shadow: var(--shadow-window);
  transition: transform var(--t-slow) var(--ease-expo), box-shadow var(--t-slow) var(--ease-expo);
}

.preview__window img { width: 100%; }

.preview__window:hover {
  transform: translateY(-6px);
  box-shadow: 0 44px 110px -34px oklch(0.08 0.05 272 / 1);
}

/* 悬浮小窗已移除（2026-10-03）：主图 app-ui.webp 里已含同一个左侧会话列表，
   两图叠加看起来是"侧栏重复了两次"。相关样式一并删掉，避免留死代码。 */

/* ---------------------------------------------------------------- 弹窗 */
.dlg {
  position: fixed;
  inset: 0;
  z-index: var(--z-modal, 90);
  display: grid;
  place-items: center;
  padding: var(--gutter);
}
.dlg[hidden] { display: none; }

.dlg__mask {
  position: absolute;
  inset: 0;
  background: oklch(0.10 0.03 272 / 0.72);
  backdrop-filter: blur(6px);
}

.dlg__box {
  position: relative;
  width: 100%;
  max-width: 480px;
  max-height: min(86vh, 720px);
  overflow: auto;
  padding: 1.75rem;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: var(--bg-deep);
  box-shadow: 0 40px 120px -30px oklch(0.06 0.04 272 / 1);
  animation: dlg-in 220ms var(--ease-out, cubic-bezier(0.22, 1, 0.36, 1));
}
.dlg__box--sm { max-width: 400px; text-align: center; }

@keyframes dlg-in {
  from { opacity: 0; transform: translateY(12px) scale(0.98); }
  to { opacity: 1; transform: none; }
}

.dlg__x {
  position: absolute;
  top: 0.9rem;
  right: 0.9rem;
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  border: 0;
  border-radius: 50%;
  background: transparent;
  color: var(--muted-2);
  cursor: pointer;
  transition: background-color var(--t-fast), color var(--t-fast);
}
.dlg__x:hover { background: oklch(1 0 0 / 0.06); color: var(--ink); }
.dlg__x svg { width: 17px; height: 17px; }

.dlg__title { font-size: 1.25rem; color: var(--ink); letter-spacing: 0.01em; text-wrap: balance; }
.dlg__sub { margin-top: 0.35rem; font-size: 0.875rem; color: var(--muted-2); }
/* text-wrap: balance 让「非常抱歉…请您耐心等候~」这种两行文案断得均匀些，
   否则会剩一个「候~」孤零零占一行 */
.dlg__text { margin-top: 0.9rem; font-size: 0.9375rem; line-height: 1.9; color: var(--muted); text-wrap: balance; }
.dlg__ok { margin-top: 1.5rem; width: 100%; }

.dl-list { margin-top: 1.4rem; display: grid; gap: 0.6rem; }

.dl-item {
  display: grid;
  grid-template-columns: 2.5rem minmax(0, 1fr) auto;
  align-items: center;
  gap: 0.85rem;
  width: 100%;
  padding: 0.95rem 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: oklch(1 0 0 / 0.02);
  color: inherit;
  text-align: left;
  font: inherit;
  cursor: pointer;
  transition: border-color var(--t-fast), background-color var(--t-fast), transform var(--t-fast);
}
.dl-item:hover {
  border-color: var(--line-strong);
  background: oklch(1 0 0 / 0.05);
  transform: translateY(-1px);
}
.dl-item:active { transform: none; }

.dl-item__icon {
  display: grid;
  place-items: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 0.7rem;
  background: oklch(0.632 0.168 264 / 0.16);
  color: var(--accent-bright);
}
.dl-item__icon svg { width: 1.15rem; height: 1.15rem; }

.dl-item__body { display: grid; gap: 0.15rem; min-width: 0; }
.dl-item__name { color: var(--ink); font-size: 0.9688rem; display: flex; align-items: center; gap: 0.5rem; }
.dl-item__tag {
  font-size: 0.6875rem;
  padding: 1px 6px;
  border-radius: 999px;
  color: var(--accent-bright);
  border: 1px solid oklch(0.691 0.143 300 / 0.45);
  background: oklch(0.691 0.143 300 / 0.12);
}
.dl-item__desc { font-size: 0.8125rem; color: var(--muted-2); overflow-wrap: anywhere; }
/* 安装包文件名不要从中间断开（会变成「Echo-Setup-」+「1.0.2.exe」两行），
   宁可整体换到下一行 */
.dl-item__desc [data-dl-file] { white-space: nowrap; }
.dl-item__arrow { color: var(--muted-2); font-size: 1rem; }

/* 通道未配置：灰掉并提示，不给死链 */
.dl-item[data-missing="1"] .dl-item__icon { background: oklch(1 0 0 / 0.05); color: var(--muted-2); }
.dl-item[data-missing="1"] .dl-item__desc { color: oklch(0.822 0.140 82 / 0.9); }

@media (max-width: 560px) {
  .dlg__box { padding: 1.4rem; }
  .dl-item { grid-template-columns: 2.25rem minmax(0, 1fr); padding: 0.85rem 0.9rem; }
  .dl-item__arrow { display: none; }
}

/* ---------------------------------------------------------------- 快速开始 */
.start-grid {
  display: grid;
  /* 条目数可能变化（现在是 6 个）：按列宽自动排，避免出现孤行 */
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: var(--space-md);
  margin-top: var(--space-xl);
}

@media (max-width: 540px) { .start-grid { grid-template-columns: 1fr; } }

.start-item {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  padding: 1.15rem 1.2rem 1.3rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: oklch(1 0 0 / 0.025);
  transition: border-color var(--t-base) var(--ease-soft),
    background-color var(--t-base) var(--ease-soft), transform var(--t-base) var(--ease-quart);
}

.start-item:hover {
  border-color: var(--line-accent);
  background: oklch(1 0 0 / 0.05);
  transform: translateY(-3px);
}

.start-item__top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  color: var(--accent-bright);
}

.start-item__top svg { width: 22px; height: 22px; }

.start-item__arrow {
  width: 16px;
  height: 16px;
  color: var(--muted-2);
  transition: transform var(--t-base) var(--ease-quart), color var(--t-base);
}

.start-item:hover .start-item__arrow {
  transform: translateX(4px);
  color: var(--ink);
}

.start-item__title { color: var(--ink); font-size: 1rem; }

.start-item__text { font-size: 0.9rem; color: var(--muted); }

/* ---------------------------------------------------------------- 页脚 */
.footer {
  position: relative;
  padding-block: clamp(2.5rem, 6vw, 4rem) clamp(1.5rem, 4vw, 2.5rem);
  background: var(--bg-void);
  border-top: 1px solid var(--line);
  overflow: hidden;
}

.footer__glow {
  position: absolute;
  inset: auto -10% -60% -10%;
  height: 70%;
  background: radial-gradient(50% 70% at 50% 100%, oklch(0.632 0.168 264 / 0.26), transparent 70%);
  pointer-events: none;
}

.footer__grid {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) repeat(2, minmax(0, 0.7fr));
  gap: var(--space-lg);
}

@media (max-width: 780px) {
  .footer__grid { grid-template-columns: 1fr; gap: var(--space-md); }
}

.footer__brand { display: flex; align-items: center; gap: 0.6rem; color: var(--ink); }

.footer__brand img { width: 30px; height: 30px; }

.footer__quote {
  margin-top: var(--space-sm);
  max-width: 30ch;
  color: var(--muted);
  line-height: 2;
}

.footer__col-title {
  font-size: 0.875rem;
  color: var(--ink);
  margin-bottom: 0.6rem;
}

.footer__links { display: grid; gap: 0.45rem; }

.footer__links a {
  font-size: 0.9rem;
  color: var(--muted);
  width: fit-content;
  transition: color var(--t-fast);
}

.footer__links a:hover { color: var(--ink); }

.footer__bottom {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-sm);
  margin-top: var(--space-xl);
  padding-top: var(--space-md);
  border-top: 1px solid var(--line);
  font-size: 0.875rem;
  color: var(--muted-2);
}

.footer__sig { font-style: normal; letter-spacing: 0.06em; }

/* ---------------------------------------------------------------- 内页头 */
.page-head {
  position: relative;
  padding-top: clamp(2.25rem, 5vw, 4rem);
  padding-bottom: clamp(1.75rem, 4vw, 3rem);
  overflow: hidden;
}

.page-head__bg {
  position: absolute;
  inset: -40% -10% auto -10%;
  height: 150%;
  background: radial-gradient(46% 58% at 70% 12%, oklch(0.632 0.168 264 / 0.26), transparent 70%),
    radial-gradient(40% 50% at 14% 26%, oklch(0.691 0.143 300 / 0.16), transparent 72%);
  pointer-events: none;
  z-index: var(--z-canvas);
}

.crumbs {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  font-size: 0.875rem;
  color: var(--muted-2);
  position: relative;
}

.crumbs a:hover { color: var(--ink); }
.crumbs span[aria-hidden] { opacity: 0.5; }

.page-head__title { margin-top: var(--space-sm); position: relative; }

.page-head__note {
  margin-top: var(--space-sm);
  color: var(--muted);
  max-width: 56ch;
  position: relative;
}

/* ---------------------------------------------------------------- 面板 / 表单 */
.panel {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: oklch(1 0 0 / 0.028);
  padding: clamp(1.25rem, 3vw, 2.25rem);
}

.panel--deep { background: var(--bg-deep); }
.panel--plain { background: transparent; border: 0; padding: 0; }

.panel__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-sm);
  flex-wrap: wrap;
}

.panel__title { font-size: 1.0625rem; color: var(--ink); }

.field { display: grid; gap: 0.45rem; }

.field__label {
  font-size: 0.9rem;
  color: var(--ink-2);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.field__hint { font-size: 0.82rem; color: var(--muted-2); }

.field__error {
  font-size: 0.85rem;
  color: var(--bad);
  min-height: 1.2em;
}

.input {
  width: 100%;
  min-height: 46px;
  padding: 0.6rem 0.9rem;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  background: oklch(0.16 0.026 270 / 0.85);
  color: var(--ink);
  transition: border-color var(--t-fast) var(--ease-soft), background-color var(--t-fast);
}

.input::placeholder { color: var(--muted); opacity: 0.72; }

.input:hover { border-color: oklch(0.55 0.05 268); }

.input:focus {
  outline: none;
  border-color: var(--focus);
  background: oklch(0.17 0.028 270);
  box-shadow: 0 0 0 3px oklch(0.632 0.168 264 / 0.22);
}

.input--code {
  font-family: "SFMono-Regular", ui-monospace, "Cascadia Mono", Consolas, monospace;
  letter-spacing: 0.22em;
  font-size: 1.05rem;
  text-align: center;
  text-transform: uppercase;
}

.input--license {
  font-family: "SFMono-Regular", ui-monospace, "Cascadia Mono", Consolas, monospace;
  letter-spacing: 0.08em;
}

.input--num { text-align: center; }

.field-row {
  display: flex;
  flex-wrap: wrap;          /* 永远允许换行，窄屏不会把按钮挤到溢出 */
  gap: 0.6rem;
  align-items: stretch;
}

/* 输入框设下限，太窄时自动换行；按钮保持自身宽度不压缩 */
.field-row .input { flex: 1 1 12rem; min-width: 0; }

.field-row .btn { flex: 1 1 auto; }

@media (min-width: 520px) {
  .field-row { flex-wrap: nowrap; }
  .field-row .btn { flex: 0 0 auto; }
}

@media (max-width: 400px) {
  .field-row .btn { flex-basis: 100%; }
}

/* 步骤指示：真实有序流程，编号在此承载信息 */
.steps {
  display: grid;
  gap: var(--space-lg);
  counter-reset: step;
}

.step {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: var(--space-sm);
  align-items: start;
}

.step__no {
  counter-increment: step;
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line-accent);
  border-radius: 50%;
  color: var(--accent-bright);
  font-size: 0.875rem;
}

.step__no::before { content: counter(step); }

.step__body { padding-top: 0.28rem; }
.step__title { font-size: 1.0625rem; color: var(--ink); }

.step__hint {
  margin-top: 0.25rem;
  font-size: 0.9rem;
  color: var(--muted);
}

.step--done .step__no {
  border-color: var(--ok);
  color: var(--ok);
  background: var(--ok-bg);
}

.step--active .step__no {
  background: oklch(0.632 0.168 264 / 0.16);
  box-shadow: 0 0 0 4px oklch(0.632 0.168 264 / 0.12);
}

/* 机器人检测面板：折叠在流程里，不喧宾夺主 */
.botcheck {
  margin-top: var(--space-sm);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: oklch(0.16 0.026 270 / 0.6);
  padding: 0.9rem 1rem;
  display: flex;
  align-items: center;
  gap: 0.85rem;
  min-height: 76px;
  transition: border-color var(--t-base), background-color var(--t-base);
}

.botcheck__box {
  width: 26px;
  height: 26px;
  flex: 0 0 auto;
  border: 1px solid var(--line-strong);
  border-radius: 7px;
  display: grid;
  place-items: center;
  color: transparent;
}

.botcheck__body { flex: 1 1 auto; min-width: 0; }

.botcheck__label { font-size: 0.9375rem; color: var(--ink-2); }

.botcheck__status { font-size: 0.82rem; color: var(--muted-2); }

.botcheck__spinner {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  border: 2px solid oklch(1 0 0 / 0.16);
  border-top-color: var(--accent-bright);
  animation: spin 700ms linear infinite;
}

@keyframes spin { to { transform: rotate(1turn); } }

.botcheck[data-state="running"] { border-color: var(--line-accent); }

.botcheck[data-state="pass"] .botcheck__box {
  border-color: var(--ok);
  background: var(--ok-bg);
  color: var(--ok);
}

.botcheck[data-state="fail"] { border-color: var(--bad); background: var(--bad-bg); }
.botcheck[data-state="fail"] .botcheck__box { border-color: var(--bad); color: var(--bad); }

.botcheck--hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

/* 结果提示 */
.alert {
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 0.85rem 1rem;
  font-size: 0.9375rem;
  display: flex;
  gap: 0.65rem;
  align-items: flex-start;
}

.alert svg { width: 18px; height: 18px; flex: 0 0 auto; margin-top: 0.28rem; }

.alert--ok { border-color: oklch(0.782 0.132 158 / 0.5); background: var(--ok-bg); color: oklch(0.9 0.08 158); }
.alert--warn { border-color: oklch(0.822 0.140 82 / 0.45); background: var(--warn-bg); color: oklch(0.92 0.08 82); }
.alert--bad { border-color: oklch(0.688 0.176 22 / 0.5); background: var(--bad-bg); color: oklch(0.9 0.09 22); }
.alert--info { background: oklch(1 0 0 / 0.04); color: var(--muted); }

.alert[hidden] { display: none; }

/* 空状态：教程/隐私未完成时使用 */
.empty-state {
  border: 1px dashed var(--line-strong);
  border-radius: var(--radius);
  padding: clamp(2.5rem, 7vw, 4.5rem) var(--space-md);
  text-align: center;
  background: oklch(1 0 0 / 0.02);
}

.empty-state__mark {
  font-size: clamp(1.4rem, 4vw, 2rem);
  color: var(--muted-2);
  letter-spacing: 0.3em;
  line-height: 1;
}

.empty-state__title {
  margin-top: var(--space-md);
  font-size: 1.125rem;
  color: var(--ink-2);
}

.empty-state__text {
  margin-top: 0.5rem;
  color: var(--muted-2);
  font-size: 0.9375rem;
}

.toast-host {
  position: fixed;
  left: 50%;
  bottom: calc(1.25rem + env(safe-area-inset-bottom, 0px));
  transform: translateX(-50%);
  z-index: var(--z-toast);
  display: grid;
  gap: 0.5rem;
  width: min(92vw, 420px);
  pointer-events: none;
}

/* 提示条出现时给页面留出底部空间，避免它盖住最后一排按钮 */
body.has-toast { padding-bottom: 5.5rem; }

.toast {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  background: oklch(0.19 0.03 270 / 0.97);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  color: var(--ink);
  padding: 0.72rem 0.95rem 0.78rem;
  font-size: 0.9rem;
  line-height: 1.6;
  box-shadow: var(--shadow-lift);
  animation: toast-in var(--t-base) var(--ease-quart) both;
}

/* 顶部一条细光代替彩色描边，和站点语言一致 */
.toast::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 2px;
  background: linear-gradient(90deg, var(--accent), var(--violet));
}

.toast--bad::before { background: var(--bad); }

@keyframes toast-in {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: none; }
}

/* ---------------------------------------------------------------- 入场动效 */
/* 默认可见；仅在 JS 就绪时由 .js 类启用位移，避免无 JS / 隐藏标签页白屏 */
.reveal { opacity: 1; }

.js .reveal {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity var(--t-reveal) var(--ease-quart), transform var(--t-reveal) var(--ease-quart);
  transition-delay: var(--reveal-delay, 0ms);
}

.js .reveal.is-in { opacity: 1; transform: none; }

.js .reveal-lite {
  opacity: 0;
  transition: opacity 700ms var(--ease-soft);
  transition-delay: var(--reveal-delay, 0ms);
}

.js .reveal-lite.is-in { opacity: 1; }

/* 首屏逐行浮现：用动画呈现，且元素默认状态就是可见的（不用永久 opacity:0）。
   脚本会在动画结束后摘掉 .rise，元素回到"完全无动画介入"的稳定状态。 */
.js .rise > * {
  animation: rise-in 1100ms var(--ease-expo) both;
}

.js .rise > *:nth-child(1) { animation-delay: 80ms; }
.js .rise > *:nth-child(2) { animation-delay: 200ms; }
.js .rise > *:nth-child(3) { animation-delay: 320ms; }
.js .rise > *:nth-child(4) { animation-delay: 440ms; }
.js .rise > *:nth-child(5) { animation-delay: 560ms; }

.js .rise.rise-done > * { animation: none; }

@keyframes rise-in {
  from { opacity: 0; transform: translateY(18px); }
  to { opacity: 1; transform: none; }
}

/* ---------------------------------------------------------------- 无障碍 */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  top: 0.5rem;
  left: 0.5rem;
  z-index: var(--z-modal);
  padding: 0.6rem 1rem;
  border-radius: var(--radius-sm);
  background: var(--accent);
  color: oklch(0.99 0 0);
  transform: translateY(-160%);
  transition: transform var(--t-base) var(--ease-quart);
}

.skip-link:focus-visible { transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }

  .js .reveal,
  .js .reveal-lite,
  .js .rise > * { opacity: 1 !important; transform: none !important; }

  .orb__ring,
  .orb__wave i,
  .orb__img { animation: none !important; }

  .ripple-field__canvas { display: none; }
}

@media print {
  .nav, .footer__glow, .orb__rings, .ripple-field { display: none; }
  body { background: #fff; color: #111; }
}

/* ==========================================================================
   教程文档
   --------------------------------------------------------------------------
   阅读型页面：窄栏、系统字体、清晰的层级。左栏目录 + 右栏正文。
   ========================================================================== */

.tut {
  display: grid;
  grid-template-columns: 250px minmax(0, 1fr);
  gap: clamp(2rem, 4vw, 4rem);
  align-items: start;
  max-width: 1080px;
  margin-inline: auto;
}

@media (max-width: 900px) {
  .tut { grid-template-columns: 1fr; gap: var(--space-lg); }
}

/* ---- 目录 ---- */
.tut-nav {
  position: sticky;
  top: 92px;
  padding-right: var(--space-sm);
  border-right: 1px solid var(--line);
}

@media (max-width: 900px) {
  .tut-nav {
    position: static;
    border-right: 0;
    border-bottom: 1px solid var(--line);
    padding: 0 0 var(--space-md);
  }
}

.tut-nav__title {
  font-size: 0.8125rem;
  color: var(--muted-2);
  letter-spacing: 0.04em;
  margin-bottom: 0.7rem;
}

.tut-nav ol { display: grid; gap: 0.1rem; counter-reset: tut; }

.tut-nav a {
  display: grid;
  grid-template-columns: 1.9rem minmax(0, 1fr);
  gap: 0.35rem;
  align-items: baseline;
  padding: 0.5rem 0.55rem;
  border-radius: var(--radius-sm);
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.55;
  transition: background-color var(--t-fast) var(--ease-soft), color var(--t-fast);
}

.tut-nav a:hover { color: var(--ink); background: oklch(1 0 0 / 0.04); }

.tut-nav a[aria-current="page"] {
  color: var(--ink);
  background: oklch(0.632 0.168 264 / 0.14);
}

.tut-nav__no {
  font-variant-numeric: tabular-nums;
  color: var(--muted-2);
  font-size: 0.8125rem;
}

.tut-nav a[aria-current="page"] .tut-nav__no { color: var(--accent-bright); }

/* ---- 正文 ---- */
.tut-body { min-width: 0; }

.tut-body > * + * { margin-top: var(--space-md); }

.tut-head {
  padding-bottom: var(--space-md);
  border-bottom: 1px solid var(--line);
  margin-bottom: var(--space-lg);
}

.tut-head__no {
  font-size: 0.8125rem;
  color: var(--accent-bright);
  letter-spacing: 0.08em;
  font-variant-numeric: tabular-nums;
}

.tut-head__title {
  margin-top: 0.4rem;
  font-size: clamp(1.5rem, 1.2rem + 1.2vw, 2rem);
  letter-spacing: -0.008em;
}

/* 章节内的小标题 */
.tut-h3 {
  margin-top: var(--space-xl);
  font-size: 1.0625rem;
  color: var(--ink);
  display: flex;
  align-items: center;
  gap: 0.55rem;
}

.tut-h3::before {
  content: "";
  width: 3px;
  height: 1em;
  border-radius: 2px;
  background: var(--accent);
  flex: 0 0 auto;
}

.tut-h3:first-child { margin-top: 0; }

.tut-body p {
  margin-top: 0.85rem;
  color: var(--muted);
  line-height: 1.95;
  max-width: 68ch;
}

/* 文档里会出现很长的 URL（比如 DeepSeek 定价页 api-docs.deepseek.com/zh-cn/quick_start/pricing），
   手机上一个不可断开的字符串会把整页撑出横向滚动条（05 章实测 407 > 390）。
   anywhere 而不是 break-word：只有 anywhere 会同时缩小 min-content，
   否则在 grid/flex 子项里仍然会被撑开。 */
.tut-body { overflow-wrap: anywhere; }

.tut-body p.tut-lead { color: var(--ink-2); }

.tut-body strong { color: var(--ink-2); font-weight: 600; }

.tut-body a { color: var(--accent-bright); text-decoration: underline; text-underline-offset: 3px; }

/* 有序/无序列表 */
.tut-list { margin-top: 0.85rem; display: grid; gap: 0.5rem; max-width: 68ch; }

.tut-list li {
  position: relative;
  padding-left: 1.35rem;
  color: var(--muted);
  line-height: 1.9;
}

.tut-list li::before {
  content: "";
  position: absolute;
  left: 0.15rem;
  top: 0.85em;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  border: 1px solid var(--line-accent);
  background: oklch(0.632 0.168 264 / 0.25);
}

.tut-list--num { counter-reset: n; }
.tut-list--num li { padding-left: 1.9rem; }
.tut-list--num li::before {
  counter-increment: n;
  content: counter(n);
  left: 0;
  top: 0.35em;
  width: 1.35rem;
  height: 1.35rem;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: oklch(0.632 0.168 264 / 0.14);
  border: 1px solid var(--line-accent);
  color: var(--accent-bright);
  font-size: 0.72rem;
  line-height: 1;
}

/* 强调块（提示 / 注意） */
.tut-note {
  margin-top: var(--space-md);
  padding: 0.9rem 1.1rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--line);
  background: oklch(1 0 0 / 0.03);
  color: var(--ink-2);
  font-size: 0.9375rem;
  line-height: 1.9;
  max-width: 68ch;
}

.tut-note--accent {
  border-color: var(--line-accent);
  background: oklch(0.632 0.168 264 / 0.08);
}

/* 费用/风险提醒：文案里有 emoji 标题 + 一段正文两块 */
.tut-note--warn {
  border-color: oklch(0.822 0.140 82 / 0.45);
  background: var(--warn-bg);
}

.tut-note__title {
  margin: 0;
  color: oklch(0.92 0.08 82);
}

.tut-note__text {
  margin: 0.3rem 0 0;
  color: var(--ink-2);
}

/* 文档里的表格 */
.tut-table-wrap {
  margin-top: var(--space-md);
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
}

.tut-table { width: 100%; border-collapse: collapse; font-size: 0.9375rem; }

.tut-table th,
.tut-table td {
  padding: 0.7rem 0.9rem;
  text-align: left;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
  line-height: 1.7;
}

.tut-table th {
  color: var(--ink);
  font-weight: 600;
  background: oklch(1 0 0 / 0.03);
  white-space: nowrap;
}

.tut-table td { color: var(--muted); }
.tut-table tr:last-child td { border-bottom: 0; }

/* 文档里的截图 */
.tut-figure {
  margin-top: var(--space-lg);
  max-width: 68ch;
}

.tut-figure img {
  width: 100%;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: var(--bg-deep);
  box-shadow: var(--shadow-lift);
}

.tut-figure figcaption {
  margin-top: 0.6rem;
  font-size: 0.8125rem;
  color: var(--muted-2);
  text-align: center;
}

/* 常见问题：Q/A 成对呈现 */
.tut-faq { margin-top: var(--space-md); display: grid; gap: 0.6rem; max-width: 68ch; }

.tut-faq details {
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: oklch(1 0 0 / 0.025);
  overflow: hidden;
}

.tut-faq summary {
  padding: 0.85rem 1rem;
  cursor: pointer;
  list-style: none;
  color: var(--ink);
  font-size: 0.9375rem;
  line-height: 1.6;
  display: flex;
  gap: 0.6rem;
  align-items: flex-start;
}

.tut-faq summary::-webkit-details-marker { display: none; }

.tut-faq summary::before {
  content: "Q";
  flex: 0 0 auto;
  width: 1.35rem;
  height: 1.35rem;
  display: grid;
  place-items: center;
  border-radius: 6px;
  background: oklch(0.632 0.168 264 / 0.18);
  color: var(--accent-bright);
  font-size: 0.72rem;
  line-height: 1;
}

.tut-faq details[open] summary { color: var(--accent-bright); }

.tut-faq .tut-faq__a {
  padding: 0 1rem 0.95rem 3.05rem;
  color: var(--muted);
  font-size: 0.9375rem;
  line-height: 1.9;
}

.tut-faq .tut-faq__a p + p { margin-top: 0.6rem; }

/* 上一章 / 下一章 */
.tut-pager {
  display: flex;
  justify-content: space-between;
  gap: var(--space-sm);
  margin-top: var(--space-2xl);
  padding-top: var(--space-md);
  border-top: 1px solid var(--line);
}

.tut-pager a {
  display: grid;
  gap: 0.2rem;
  min-width: 12rem;
  max-width: 46%;
  padding: 0.7rem 0.9rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  transition: border-color var(--t-fast), background-color var(--t-fast);
}

.tut-pager a:hover { border-color: var(--line-accent); background: oklch(1 0 0 / 0.03); }

.tut-pager__label { font-size: 0.75rem; color: var(--muted-2); }
.tut-pager__title { font-size: 0.9375rem; color: var(--ink-2); }

.tut-pager a:last-child { text-align: right; margin-left: auto; }

@media (max-width: 560px) {
  .tut-pager { flex-direction: column; }
  .tut-pager a { max-width: none; min-width: 0; }
  .tut-pager a:last-child { text-align: left; margin-left: 0; }

  /* 手机上表格首列收窄，避免"支付方式"这类短词被折成两行 */
  .tut-table { font-size: 0.9rem; }
  .tut-table th,
  .tut-table td { padding: 0.6rem 0.7rem; }
  .tut-table th:first-child,
  .tut-table td:first-child { min-width: 6.2em; white-space: nowrap; }
  .tut-table th { white-space: nowrap; }
}

/* 未完成的章节 */
.tut-empty {
  margin-top: var(--space-md);
  border: 1px dashed var(--line-strong);
  border-radius: var(--radius);
  padding: clamp(2rem, 6vw, 3.5rem) var(--space-md);
  text-align: center;
  background: oklch(1 0 0 / 0.02);
  max-width: 68ch;
}

.tut-empty__mark {
  font-size: 1.35rem;
  letter-spacing: 0.28em;
  color: var(--muted-2);
}

.tut-empty__text { margin-top: 0.8rem; color: var(--muted); font-size: 0.9375rem; }

/* 教程总目录页头：标题与「观看视频教程」并排 */
.tut-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--space-md) var(--space-lg);
  flex-wrap: wrap;
}

.tut-head .page-head__title { flex: 1 1 auto; min-width: 0; }
.tut-head__cta { flex: 0 0 auto; }

@media (max-width: 560px) {
  .tut-head { align-items: stretch; }
  .tut-head__cta { width: 100%; justify-content: center; }
}

/* 教程总目录页 */
.tut-index { display: grid; gap: 0; margin-top: var(--space-lg); border-top: 1px solid var(--line); }

.tut-index a {
  display: grid;
  grid-template-columns: 3rem minmax(0, 1fr) auto;
  gap: var(--space-sm);
  align-items: center;
  padding: 1.1rem 0.25rem;
  border-bottom: 1px solid var(--line);
  transition: background-color var(--t-fast);
}

.tut-index a:hover { background: oklch(1 0 0 / 0.03); }

.tut-index__no {
  font-size: 1rem;
  color: var(--muted-2);
  font-variant-numeric: tabular-nums;
}

.tut-index a:hover .tut-index__no { color: var(--accent-bright); }

.tut-index__title { color: var(--ink); font-size: 1.0625rem; }

.tut-index__meta { font-size: 0.8125rem; color: var(--muted-2); white-space: nowrap; }

.tut-index__meta--soon { color: oklch(0.822 0.140 82 / 0.9); }

/* 窄屏：编号占第一列并跨两行，标题与状态都放在第二列上下排。
   必须显式指定 grid-column/grid-row —— 之前只改了列数，第三个子元素
   （状态）被自动塞进 2.2rem 宽的编号列，于是「可阅读」被挤成「可阅 / 读」。 */
@media (max-width: 620px) {
  .tut-index a {
    grid-template-columns: 2rem minmax(0, 1fr);
    row-gap: 0.15rem;
    padding-block: 0.95rem;
    align-items: start;
  }
  .tut-index__no { grid-column: 1; grid-row: 1; align-self: start; line-height: 1.5; }
  .tut-index__title { grid-column: 2; grid-row: 1; }
  .tut-index__meta { grid-column: 2; grid-row: 2; white-space: normal; }
}

/* ==========================================================================
   表单页（建议反馈 / 申请退款）
   ========================================================================== */

.form-page { max-width: 720px; margin-inline: auto; }

.form-head { text-align: center; padding-block: clamp(1.75rem, 4vw, 3rem) var(--space-lg); }
.form-head__mark {
  width: 46px;
  height: 46px;
  margin: 0 auto 1rem;
  display: grid;
  place-items: center;
  border: 1px solid var(--line-accent);
  border-radius: 50%;
  color: var(--accent-bright);
  background: oklch(0.632 0.168 264 / 0.10);
}
.form-head__mark svg { width: 21px; height: 21px; }
.form-head__title { font-size: clamp(1.6rem, 1.2rem + 1.6vw, 2.15rem); letter-spacing: -0.01em; }
.form-head__note { margin-top: 0.7rem; color: var(--muted); line-height: 1.9; }
.form-head__note a { color: var(--accent-bright); text-decoration: underline; text-underline-offset: 3px; }

/* 表单主体 */
.form-card {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: oklch(1 0 0 / 0.028);
  padding: clamp(1.35rem, 3.4vw, 2.25rem);
}

.form-grid { display: grid; gap: var(--space-md); }

.field--row { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: var(--space-sm); }
@media (max-width: 560px) { .field--row { grid-template-columns: 1fr; } }

.field__label .req { color: var(--accent-bright); margin-left: 0.15rem; }
.field__label .opt { color: var(--muted-2); font-size: 0.8125rem; margin-left: 0.3rem; }

textarea.input {
  min-height: 132px;
  line-height: 1.8;
  resize: vertical;
  padding: 0.7rem 0.9rem;
}

.char-count { font-size: 0.8125rem; color: var(--muted-2); text-align: right; }
.char-count--warn { color: var(--warn); }
.char-count--ok { color: oklch(0.86 0.1 158); }
/* 选择项（退款方式） */
.choice-row { display: flex; flex-wrap: wrap; gap: 0.6rem; }

.choice {
  flex: 1 1 8rem;
  position: relative;
  display: flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.7rem 0.9rem;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: border-color var(--t-fast), background-color var(--t-fast);
}

.choice:hover { border-color: var(--line-accent); }
.choice input { position: absolute; opacity: 0; pointer-events: none; }
.choice__dot {
  width: 16px;
  height: 16px;
  flex: 0 0 auto;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  display: grid;
  place-items: center;
}
.choice__dot::after {
  content: "";
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  transform: scale(0);
  transition: transform var(--t-fast) var(--ease-quart);
}
.choice input:checked ~ .choice__dot { border-color: var(--accent-bright); }
.choice input:checked ~ .choice__dot::after { transform: scale(1); }
.choice__text { font-size: 0.9375rem; color: var(--ink-2); }
.choice:has(input:checked) { border-color: var(--line-accent); background: oklch(0.632 0.168 264 / 0.10); }
.choice:has(input:focus-visible) { outline: 2px solid var(--focus); outline-offset: 2px; }

/* 上传控件 */
.upload { display: grid; gap: 0.5rem; }

.upload__drop {
  display: grid;
  place-items: center;
  gap: 0.4rem;
  padding: 1.2rem 1rem;
  border: 1px dashed var(--line-strong);
  border-radius: var(--radius-sm);
  background: oklch(1 0 0 / 0.02);
  cursor: pointer;
  text-align: center;
  transition: border-color var(--t-fast), background-color var(--t-fast);
}
.upload__drop:hover { border-color: var(--line-accent); background: oklch(0.632 0.168 264 / 0.06); }
.upload__drop svg { width: 20px; height: 20px; color: var(--accent-bright); }
.upload__hint { font-size: 0.85rem; color: var(--muted); }
.upload__sub { font-size: 0.78rem; color: var(--muted-2); }
.upload input[type="file"] { position: absolute; width: 1px; height: 1px; opacity: 0; pointer-events: none; }

.upload__preview { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.upload__thumb {
  position: relative;
  width: 84px;
  height: 84px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--bg-deep);
}
.upload__thumb img { width: 100%; height: 100%; object-fit: cover; }
.upload__thumb button {
  position: absolute;
  top: 2px;
  right: 2px;
  width: 20px;
  height: 20px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: oklch(0.15 0.02 270 / 0.85);
  color: var(--ink);
  font-size: 0.75rem;
  line-height: 1;
}

/* 退款条件清单 */
.terms {
  border: 1px solid var(--line-accent);
  border-radius: var(--radius);
  background: oklch(0.632 0.168 264 / 0.07);
  padding: clamp(1.1rem, 2.6vw, 1.6rem);
}

.terms__title {
  font-size: 0.8125rem;
  letter-spacing: 0.06em;
  color: var(--accent-bright);
}

.terms__lead { margin-top: 0.6rem; color: var(--ink); font-size: 1.0625rem; line-height: 1.75; }

.terms__list { margin-top: var(--space-sm); display: grid; gap: 0.5rem; }

.terms__list li {
  position: relative;
  padding-left: 1.5rem;
  color: var(--ink-2);
  font-size: 0.9375rem;
  line-height: 1.85;
}

.terms__list li::before {
  content: "";
  position: absolute;
  left: 0.1rem;
  top: 0.55em;
  width: 12px;
  height: 7px;
  border-left: 1.6px solid var(--ok);
  border-bottom: 1.6px solid var(--ok);
  transform: rotate(-45deg);
}

.terms__note { margin-top: var(--space-sm); font-size: 0.875rem; color: var(--muted); line-height: 1.85; }

/* 同意勾选 */
.consent-box {
  display: flex;
  gap: 0.7rem;
  align-items: flex-start;
  padding: 0.85rem 1rem;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  background: oklch(1 0 0 / 0.025);
  cursor: pointer;
  font-size: 0.9375rem;
  color: var(--ink-2);
  line-height: 1.8;
}

.consent-box input {
  appearance: none;
  width: 18px;
  height: 18px;
  margin-top: 0.28rem;
  flex: 0 0 auto;
  border: 1px solid var(--line-strong);
  border-radius: 5px;
  background: transparent;
  cursor: pointer;
  display: grid;
  place-items: center;
  transition: border-color var(--t-fast), background-color var(--t-fast);
}

.consent-box input::after {
  content: "";
  width: 10px;
  height: 6px;
  border-left: 1.8px solid oklch(0.99 0 0);
  border-bottom: 1.8px solid oklch(0.99 0 0);
  transform: rotate(-45deg) scale(0);
  transition: transform var(--t-fast) var(--ease-quart);
}

.consent-box input:checked { background: var(--accent); border-color: var(--accent-bright); }
.consent-box input:checked::after { transform: rotate(-45deg) scale(1); }
.consent-box:has(input:focus-visible) { outline: 2px solid var(--focus); outline-offset: 2px; }

/* 提交区 */
.form-actions { margin-top: var(--space-lg); display: grid; gap: 0.85rem; }

.form-note { font-size: 0.8125rem; color: var(--muted-2); text-align: center; line-height: 1.8; }

/* 机器人校验（复用激活页样式，这里只补一个紧凑版） */
.botcheck--compact { min-height: 64px; }

/* 提交成功卡片 */
.done-card {
  border: 1px solid oklch(0.782 0.132 158 / 0.45);
  border-radius: var(--radius);
  background: var(--ok-bg);
  padding: clamp(1.5rem, 3.4vw, 2.25rem);
  text-align: center;
}

.done-card__icon {
  width: 46px;
  height: 46px;
  margin: 0 auto 1rem;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: oklch(0.782 0.132 158 / 0.18);
  color: var(--ok);
}
.done-card__icon svg { width: 24px; height: 24px; }
.done-card__title { font-size: 1.25rem; color: var(--ink); }
.done-card__text { margin-top: 0.7rem; color: var(--ink-2); line-height: 1.9; font-size: 0.9375rem; }
.done-card__meta {
  margin-top: var(--space-md);
  padding-top: var(--space-md);
  border-top: 1px solid oklch(0.782 0.132 158 / 0.28);
  font-size: 0.875rem;
  color: var(--muted);
  line-height: 1.9;
}
.done-card__no { font-family: "SFMono-Regular", ui-monospace, Consolas, monospace; color: var(--ink); }

/* 首页快速开始里的两个新入口用同一套卡片样式，无需新增类 */