/* ============================================================
   KOTOBA·AI 网站 — 主样式（26.0 设计系统）
   Token 与组件语言对照 ../KotobaAI-26/docs/26/design-system.md：
   纸面墨字 / 平色 / 细边框 / 小圆角 / 品牌红稀缺使用，仅浅色主题。
   2026-09-17 起替代 7.0 黏土体系（D-2026-09-17-02）。
   ============================================================ */

/* DM Sans（26.0 UI 字体，自托管；Nunito 已随黏土体系退役） */
@font-face {
  font-family: "DM Sans";
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url("../static/fonts/dm-sans-latin.woff2") format("woff2");
}

:root {
  /* 26.0 token（引用不复制：源头 ../KotobaAI-26/docs/26/design-system.md） */
  --brand-600: #F00000;
  --brand-700: #C80000;
  --ink-900: #2E2A2C;
  --ink-700: #5C5659;
  --ink-500: #8F888B;
  --ink-300: #DCD7D9;
  --ink-200: #EAE6E7;
  --ink-100: #F4F1F2;
  --paper-page: #FAF9F7;
  --paper-surface: #FFFFFF;
  --green-600: #1E8E5A;
  --amber-600: #B97A00;
  --blue-600: #2E6FD8;
  --ms-blue: #0078D4;   /* 微软商店通道主题色 */
  --gh-black: #24292F;  /* GitHub 通道主题色 */
  --hl-vocab: #FFF3B0;
  --hl-grammar: #FDE4E2;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-xl: 18px;
  --radius-full: 999px;
  --shadow-sm: 0 1px 2px rgba(28, 24, 26, 0.05);
  --shadow-md: 0 2px 8px rgba(28, 24, 26, 0.10);
  --font-body: "DM Sans", "Segoe UI", "Microsoft YaHei", "PingFang SC", sans-serif;
  --font-ja: "Noto Serif JP", "Yu Mincho", "YuMincho", "Hiragino Mincho ProN", serif;
  --transition-fast: 120ms cubic-bezier(0.2, 0, 0, 1);

  /* main.js 内联样式引用的两个旧名别名（showTip 的提示色），勿删 */
  --color-primary: var(--brand-600);
  --color-success: var(--green-600);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  background: var(--paper-page);
  color: var(--ink-900);
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.6;
}
::selection { background: var(--brand-600); color: #fff; }
.container { max-width: 1100px; margin: 0 auto; padding: 0 20px; }
.container--narrow { max-width: 760px; }
h1, h2, h3, h4 { font-weight: 700; letter-spacing: -0.01em; }
a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }
img { max-width: 100%; }

/* ---------- Button ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  border-radius: var(--radius-md); font-weight: 600;
  transition: background var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast);
}
.btn:active { transform: scale(0.98); }
.btn-lg { height: 48px; padding: 14px 28px; font-size: 16px; }
.btn-md { height: 40px; padding: 10px 20px; font-size: 14px; }
.btn-sm { height: 32px; padding: 6px 12px; font-size: 13px; }
.btn-primary { background: var(--brand-600); color: #fff; }
.btn-primary:hover { background: var(--brand-700); }
.btn-secondary {
  background: var(--paper-surface); color: var(--ink-900); border: 1px solid var(--ink-300);
}
.btn-secondary:hover { background: var(--ink-100); border-color: var(--ink-500); }
.btn-ms { background: var(--ms-blue); color: #fff; }
.btn-ms:hover { background: #106EBE; }
.btn-gh { background: var(--gh-black); color: #fff; }
.btn-gh:hover { background: #3A4148; }

/* ---------- Card ---------- */
.card {
  background: var(--paper-surface);
  border: 1px solid var(--ink-200);
  border-radius: var(--radius-lg);
  padding: 24px;
}

/* ---------- 区块 ---------- */
.section { padding: 56px 0; }
.section + .section { border-top: 1px solid var(--ink-200); }
.section-title { font-size: 24px; line-height: 1.3; border-left: 3px solid var(--brand-600); padding-left: 10px; }
.section-sub { font-size: 15px; color: var(--ink-700); margin-top: 8px; }

/* ---------- 导航 ---------- */
.nav {
  position: sticky; top: 0; z-index: 20;
  background: var(--paper-page);
  border-bottom: 1px solid var(--ink-200);
  transition: box-shadow var(--transition-fast);
}
/* 吸顶后加投影（js/main.js 滚动监听切换 nav--scrolled） */
.nav--scrolled { box-shadow: var(--shadow-md); }
.nav-inner { display: flex; align-items: center; gap: 24px; height: 60px; }
.nav-logo { display: flex; align-items: center; gap: 8px; font-weight: 700; font-size: 17px; margin-right: auto; }
.nav-logo img { width: 26px; height: 26px; }
.nav-logo .dot { color: var(--brand-600); }
.nav-links { display: flex; align-items: center; gap: 22px; font-size: 14px; font-weight: 500; color: var(--ink-700); }
.nav-links > a:not(.btn):hover { color: var(--ink-900); }
.nav-links > a.active { color: var(--brand-600); font-weight: 600; }
.join-logo { height: 20px; display: block; }
.nav-actions { display: flex; align-items: center; gap: 12px; }
.nav-burger { display: none; font-size: 18px; color: var(--ink-700); padding: 4px 8px; }

/* ---------- 页脚 ---------- */
footer { border-top: 1px solid var(--ink-200); padding: 32px 0; color: var(--ink-500); font-size: 13px; }
.footer-inner { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 16px; }
.footer-brand { display: flex; align-items: center; gap: 8px; font-weight: 700; color: var(--ink-900); font-size: 15px; }
.footer-brand .dot { color: var(--brand-600); }
.footer-links { display: flex; gap: 20px; align-items: center; flex-wrap: wrap; }
.footer-links a:hover, .footer-links button:hover { color: var(--ink-900); }
.footer-links img { height: 16px; display: block; }
.footer-legal { font-size: 12px; }

/* ---------- Hero ---------- */
.hero { padding: 64px 0; }
.hero-badge {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: 13px; font-weight: 600; color: var(--ink-700);
  background: var(--paper-surface); border: 1px solid var(--ink-300);
  border-radius: var(--radius-full); padding: 5px 14px; margin-bottom: 24px;
}
.hero-badge .dot { width: 6px; height: 6px; border-radius: var(--radius-full); background: var(--brand-600); }
.hero h1 { font-size: 44px; line-height: 1.2; max-width: 640px; }
.hero .sub { font-size: 17px; line-height: 1.7; color: var(--ink-700); max-width: 560px; margin: 20px 0 32px; }
.hero-cta { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.hero-version { font-size: 13px; color: var(--ink-500); }

/* ---------- 学习循环六步 ---------- */
.loop-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-top: 32px; }
.loop-step { background: var(--paper-surface); border: 1px solid var(--ink-200); border-radius: var(--radius-lg); padding: 24px; }
.loop-step .no {
  display: inline-flex; width: 28px; height: 28px; border-radius: var(--radius-full);
  background: rgba(240, 0, 0, 0.08); color: var(--brand-600);
  font-weight: 700; font-size: 14px; align-items: center; justify-content: center; margin-bottom: 10px;
}
.loop-step h3 { font-size: 16px; font-weight: 600; margin-bottom: 6px; }
.loop-step p { font-size: 14px; color: var(--ink-700); }

/* ---------- 功能：UI 演示（按软件本体真实结构绘制，非截图） ---------- */
.feature-row { display: grid; grid-template-columns: 300px 1fr; gap: 32px; align-items: center; margin-top: 40px; }
.feature-row.rev { grid-template-columns: 1fr 300px; }
.feature-row.rev .desc { order: 2; }
.feature-row .desc .k { font-size: 12px; font-weight: 600; color: var(--brand-600); letter-spacing: 0.06em; }
.feature-row .desc h3 { font-size: 20px; margin: 8px 0 10px; }
.feature-row .desc p { font-size: 14px; color: var(--ink-700); }
.feature-row .desc .points { margin-top: 12px; display: flex; flex-direction: column; gap: 6px; }
.feature-row .desc .points span { font-size: 13px; color: var(--ink-700); padding-left: 14px; position: relative; }
.feature-row .desc .points span::before {
  content: ""; position: absolute; left: 0; top: 8px; width: 5px; height: 5px;
  border-radius: var(--radius-full); background: var(--brand-600);
}
.feature-frame {
  border: 1px solid var(--ink-200); border-radius: var(--radius-lg);
  background: var(--paper-surface); overflow: hidden; font-size: 13px;
}
.ff-bar {
  display: flex; align-items: center; justify-content: space-between; gap: 8px;
  padding: 10px 14px; border-bottom: 1px solid var(--ink-200); background: var(--paper-page);
}
.ff-bar .t { font-weight: 600; font-size: 13px; }
.ff-bar .muted { color: var(--ink-500); font-size: 12px; }
.ff-body { padding: 16px; }
.steps-dots { display: flex; gap: 5px; }
.steps-dots i { width: 7px; height: 7px; border-radius: var(--radius-full); background: var(--ink-300); }
.steps-dots i.on { background: var(--brand-600); }
.steps-dots i.done { background: rgba(240, 0, 0, 0.35); }
.src-line { font-size: 12px; color: var(--ink-500); margin-bottom: 12px; }
.src-line b { color: var(--ink-700); font-weight: 600; }
.chip {
  display: inline-flex; align-items: center; gap: 6px; height: 26px; padding: 0 10px;
  border-radius: var(--radius-full); background: var(--ink-100);
  font-size: 12px; font-weight: 500; color: var(--ink-700);
}
.chip.gram { background: var(--paper-surface); border: 1px solid var(--ink-300); }
.badge { display: inline-flex; align-items: center; height: 20px; padding: 0 8px; border-radius: var(--radius-sm); font-size: 11px; font-weight: 600; }
.badge-extra { background: var(--ink-100); color: var(--ink-700); }
.badge-diff { background: rgba(240, 0, 0, 0.08); color: var(--brand-600); }
.q-ja { font-family: var(--font-ja); font-size: 18px; line-height: 1.75; margin: 12px 0; }
.q-ja rt { font-size: 11px; color: var(--ink-500); }
.scene-line { font-size: 12px; color: var(--ink-500); margin: 6px 0 2px; }
.answer-row { display: flex; gap: 8px; margin-top: 12px; }
.answer-row .fake-input {
  flex: 1; height: 38px; border: 1px solid var(--ink-300); border-radius: var(--radius-md);
  background: var(--paper-surface); padding: 9px 12px; font-size: 13px; color: var(--ink-500);
}
.answer-hint { font-size: 12px; color: var(--ink-500); margin-top: 6px; }
/* 逐题批改（做完一道改一道） */
.fb-ico {
  flex: none; width: 20px; height: 20px; border-radius: var(--radius-full);
  display: flex; align-items: center; justify-content: center; margin-top: 1px;
}
.fb-ico svg { width: 12px; height: 12px; }
.fb-ok { background: rgba(30, 142, 90, 0.12); } .fb-ok svg { stroke: var(--green-600); }
.fb-ng { background: rgba(240, 0, 0, 0.10); } .fb-ng svg { stroke: var(--brand-600); }
.fb-tip { background: rgba(46, 111, 216, 0.10); } .fb-tip svg { stroke: var(--blue-600); }
.fb-body { flex: 1; }
.fb-body .t { font-size: 13px; font-weight: 600; }
.fb-body .t .tag { font-size: 12px; font-weight: 600; margin-left: 6px; }
.fb-body p { font-size: 13px; color: var(--ink-700); margin-top: 3px; }
.fb-line { display: flex; gap: 10px; padding: 10px 0; border-top: 1px solid var(--ink-200); }
.fb-line:first-child { border-top: none; }
.ai-block {
  margin-top: 10px; padding: 12px 14px; background: var(--ink-100);
  border-left: 3px solid var(--blue-600); border-radius: var(--radius-sm);
}
.ai-block .head { display: flex; align-items: center; gap: 6px; font-size: 12px; font-weight: 600; color: var(--blue-600); margin-bottom: 4px; }
.ai-block .head svg { width: 13px; height: 13px; stroke: var(--blue-600); }
.ai-block p { font-size: 13px; color: var(--ink-700); line-height: 1.7; margin: 0; }
.cursor {
  display: inline-block; width: 2px; height: 1em; background: var(--brand-600);
  vertical-align: -0.15em; animation: blink 600ms step-end infinite;
}
@keyframes blink { 50% { opacity: 0; } }
.answered {
  margin-top: 12px; padding: 12px 14px; border: 1px solid var(--ink-200);
  border-radius: var(--radius-md); background: var(--paper-page);
}
.answered .you { font-size: 12px; color: var(--ink-500); margin-bottom: 2px; }
.answered .ja { font-family: var(--font-ja); font-size: 15px; }

/* 学习台（App 首页真实结构） */
.appframe {
  display: grid; grid-template-columns: 48px 1fr;
  border: 1px solid var(--ink-200); border-radius: var(--radius-lg);
  overflow: hidden; background: var(--paper-surface);
}
.app-side {
  background: var(--paper-page); border-right: 1px solid var(--ink-200); padding: 12px 0;
  display: flex; flex-direction: column; align-items: center; gap: 10px;
}
.side-ico {
  width: 32px; height: 32px; border-radius: var(--radius-md);
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 3px; font-size: 9px; color: var(--ink-500);
}
.side-ico .bar { width: 14px; height: 14px; border-radius: 4px; background: var(--ink-300); }
.side-ico.active { background: rgba(240, 0, 0, 0.08); box-shadow: inset 3px 0 0 var(--brand-600); color: var(--brand-600); }
.side-ico.active .bar { background: var(--brand-600); }
.app-main { padding: 16px; }
.status-strip { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; }
.status-strip .chip b { color: var(--ink-900); }
.desk-grid { display: grid; grid-template-columns: 1.2fr 1fr; gap: 12px; }
.desk-card { border: 1px solid var(--ink-200); border-radius: var(--radius-lg); padding: 14px; }
.desk-card .h { font-size: 12px; font-weight: 600; color: var(--ink-700); margin-bottom: 8px; }
.desk-cta-title { font-size: 15px; font-weight: 700; }
.desk-cta-sub { font-size: 12px; color: var(--ink-700); margin: 4px 0 10px; }
.weak li { display: flex; justify-content: space-between; list-style: none; padding: 6px 0; border-bottom: 1px solid var(--ink-200); font-size: 12px; }
.weak li:last-child { border-bottom: none; }
.weak .pct { font-family: Consolas, monospace; color: var(--ink-500); font-size: 11px; }
.weak .pct.low { color: var(--brand-600); font-weight: 600; }
.rq-bars { display: flex; align-items: flex-end; gap: 6px; height: 52px; margin-top: 6px; }
.rq-bars .col { flex: 1; display: flex; flex-direction: column; align-items: center; gap: 4px; }
.rq-bars .col i { width: 100%; border-radius: 4px 4px 0 0; background: var(--brand-600); opacity: 0.45; }
.rq-bars .col.today i { opacity: 1; }
.rq-bars .col span { font-size: 10px; color: var(--ink-500); }
.hist-row { display: flex; justify-content: space-between; padding: 6px 0; border-bottom: 1px solid var(--ink-200); font-size: 12px; }
.hist-row:last-child { border-bottom: none; }
.hist-row .mono { font-family: Consolas, monospace; color: var(--ink-500); font-size: 11px; }

/* 精读 / 闪卡 / 错题本 */
.reading-text { font-family: var(--font-ja); font-size: 15px; line-height: 2; }
.reading-text .v { background: var(--hl-vocab); border-radius: 3px; padding: 0 2px; }
.reading-text .g { background: var(--hl-grammar); border-radius: 3px; padding: 0 2px; }
.basket {
  display: flex; align-items: center; flex-wrap: wrap; gap: 6px; margin-top: 12px;
  padding-top: 12px; border-top: 1px solid var(--ink-200);
}
.flash-wrap { display: flex; flex-direction: column; align-items: center; gap: 12px; padding: 8px 0; }
.flash-card {
  width: min(320px, 100%); text-align: center; border: 1px solid var(--ink-200);
  border-radius: var(--radius-lg); padding: 24px 16px;
}
.flash-card .w { font-family: var(--font-ja); font-size: 24px; }
.flash-card .r { font-size: 12px; color: var(--ink-500); margin-top: 4px; }
.flash-card .hint { font-size: 12px; color: var(--ink-500); margin-top: 12px; }
.flash-actions { display: flex; gap: 8px; width: min(320px, 100%); }
.flash-actions .btn { flex: 1; }
.va-again { background: var(--paper-surface); border: 1px solid var(--ink-300); color: var(--ink-700); }
.va-hard { background: var(--paper-surface); border: 1px solid var(--amber-600); color: var(--amber-600); }
.va-good { background: var(--paper-surface); border: 1px solid var(--green-600); color: var(--green-600); }
.prog-row { display: flex; align-items: center; gap: 10px; width: min(320px, 100%); }
.prog-row .meter { flex: 1; margin: 0; }
.meter { height: 6px; border-radius: var(--radius-full); background: var(--ink-200); overflow: hidden; margin: 5px 0; }
.meter i { display: block; height: 100%; border-radius: var(--radius-full); }
.m-green { background: var(--green-600); } .m-amber { background: var(--amber-600); } .m-red { background: var(--brand-600); }
.wb-group {
  border: 1px solid var(--ink-200); border-radius: var(--radius-md); padding: 10px 14px; margin-bottom: 8px;
  display: flex; align-items: center; justify-content: space-between; gap: 8px;
}
.wb-group .n { font-weight: 600; font-size: 13px; }
.wb-group .meta { font-size: 12px; color: var(--ink-500); }

/* ---------- 能做什么 ---------- */
.stats-band { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-top: 32px; }
.stat { background: var(--paper-surface); border: 1px solid var(--ink-200); border-radius: var(--radius-lg); padding: 24px; text-align: center; }
.stat .num { font-size: 30px; font-weight: 700; }
.stat .num em { font-style: normal; color: var(--brand-600); }
.stat .lbl { font-size: 13px; color: var(--ink-700); margin-top: 4px; }
.minifeats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin-top: 16px; }
.minifeat {
  font-size: 13px; color: var(--ink-700); background: var(--paper-surface);
  border: 1px solid var(--ink-200); border-radius: var(--radius-md); padding: 12px 14px;
}
.minifeat b { display: block; font-size: 13px; color: var(--ink-900); font-weight: 600; margin-bottom: 2px; }

/* ---------- 本地与信任 ---------- */
.trust-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 32px; }
.trust-card h3 { font-size: 15px; font-weight: 600; margin-bottom: 8px; }
.trust-card p { font-size: 14px; color: var(--ink-700); }
.trust-card code { font-family: Consolas, monospace; font-size: 12px; background: var(--ink-100); border-radius: var(--radius-sm); padding: 1px 6px; }

/* ---------- 下载页：三通道 ---------- */
.channel-grid { display: grid; grid-template-columns: 1.3fr 1fr 1fr; gap: 16px; margin-top: 32px; }
.channel-card { position: relative; display: flex; flex-direction: column; }
.channel-card .tagrow { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; }
.channel-card .tagrow .logo { flex: none; display: flex; }
.channel-card h3 { font-size: 17px; font-weight: 600; flex: 1; }
.channel-card p { font-size: 13px; color: var(--ink-700); margin: 6px 0 14px; flex: 1; }
.ch-main { border-color: rgba(240, 0, 0, 0.35); }
.ch-ms { border-top: 3px solid var(--ms-blue); }
.ch-gh { border-top: 3px solid var(--gh-black); }
.pri-tag {
  font-size: 11px; font-weight: 600; color: var(--brand-600);
  background: rgba(240, 0, 0, 0.06); border-radius: var(--radius-full); padding: 2px 10px;
}
.meta-line { font-size: 12px; color: var(--ink-500); margin-top: 10px; }
.howto-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-top: 16px; }
.howto-card h3 { font-size: 15px; font-weight: 600; margin-bottom: 6px; }
.howto-card .stepno { color: var(--brand-600); margin-right: 6px; }
.howto-card p { font-size: 13px; color: var(--ink-700); }
.req-list { list-style: none; margin-top: 24px; display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.req-list li {
  display: flex; gap: 10px; align-items: flex-start; font-size: 14px; color: var(--ink-700);
  background: var(--paper-surface); border: 1px solid var(--ink-200); border-radius: var(--radius-md); padding: 12px 16px;
}
.req-list li b { color: var(--ink-900); }
table.hist { width: 100%; border-collapse: collapse; margin-top: 14px; font-size: 14px; }
table.hist th { text-align: left; color: var(--ink-500); font-size: 13px; font-weight: 600; padding: 10px 0; border-bottom: 1px solid var(--ink-200); }
table.hist td { padding: 12px 0; border-bottom: 1px solid var(--ink-200); }
table.hist tr:last-child td { border-bottom: none; }
.hist__label { font-size: 12px; color: var(--ink-500); margin-left: 8px; }
.hist__na { color: var(--ink-500); }
.changelog-item { border-left: 3px solid var(--ink-200); padding: 2px 0 2px 16px; margin-top: 20px; }
.changelog-item h3 { font-size: 16px; font-weight: 600; }
.changelog-item .date { font-size: 13px; color: var(--ink-500); font-weight: 400; margin-left: 8px; }
.changelog-item p { font-size: 14px; color: var(--ink-700); margin-top: 8px; }
.changelog-item ul { margin: 8px 0 0 18px; font-size: 14px; color: var(--ink-700); }
.changelog-item li { margin-top: 6px; }

/* ---------- FAQ（details 手风琴，js/main.js 同时只开一个） ---------- */
.faq-list { margin-top: 32px; }
details.faq-item {
  background: var(--paper-surface); border: 1px solid var(--ink-200); border-radius: var(--radius-lg);
  padding: 20px 24px; margin-bottom: 12px; width: 100%;
}
details.faq-item[open] { border-color: var(--ink-300); }
details.faq-item summary {
  list-style: none; font-size: 15px; font-weight: 600;
  display: flex; justify-content: space-between; align-items: center; gap: 12px; cursor: pointer;
}
details.faq-item summary::-webkit-details-marker { display: none; }
details.faq-item summary .mk { color: var(--ink-500); font-weight: 400; flex: none; }
details.faq-item .a { font-size: 14px; color: var(--ink-700); margin-top: 10px; }
details.faq-item .a code { font-family: Consolas, monospace; font-size: 13px; background: var(--ink-100); border-radius: var(--radius-sm); padding: 1px 6px; }

/* ---------- 意见反馈页 ---------- */
.fb-page-sub { text-align: center; font-size: 15px; color: var(--ink-700); margin-top: 8px; }
.fb-form-card { max-width: 720px; margin: 32px auto 0; }
.fb-form { display: flex; flex-direction: column; gap: 4px; }
.form-field { margin-bottom: 20px; }
.form-label { display: block; font-size: 13px; font-weight: 600; margin-bottom: 8px; }
.form-label .fb-form__hint { font-weight: 400; color: var(--ink-500); }
.form-input, .fb-select__btn, textarea.fb-form__input, input.fb-form__input {
  width: 100%; border: 1px solid var(--ink-300); border-radius: var(--radius-md);
  background: var(--paper-surface); font-size: 14px; color: var(--ink-900);
}
textarea.fb-form__input { min-height: 130px; padding: 10px 14px; line-height: 1.7; resize: vertical; font-family: var(--font-body); }
input.fb-form__input { height: 42px; padding: 10px 14px; }
.fb-form__hint { font-size: 12px; color: var(--ink-500); }
.form-2col { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.form-hint { font-size: 12px; color: var(--ink-500); margin-top: 6px; }
.fb-form .btn[type="submit"], .fb-form .btn-lg { width: 100%; margin-top: 4px; }
.fb-form__tip { margin-top: 12px; font-size: 14px; }
.fb-form__aside { color: var(--ink-500); font-size: 14px; margin-top: 20px; text-align: center; }
/* 自绘下拉（原生 option 弹层是系统绘制的无法美化，故整体替换为按钮+列表；
   真 select 仍保留在 DOM 中承载表单值，js 在页面内联脚本处理开合） */
.fb-select { position: relative; display: block; }
.fb-select__btn {
  display: flex; align-items: center; justify-content: space-between;
  height: 42px; padding: 10px 14px; text-align: left; cursor: pointer;
  transition: border-color var(--transition-fast);
}
.fb-select__btn::after {
  content: ""; width: 14px; height: 14px; flex: none;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='14' height='14' viewBox='0 0 24 24' fill='none' stroke='%238F888B' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E") no-repeat center / contain;
  transition: transform var(--transition-fast);
}
.fb-select.open .fb-select__btn { border-color: var(--brand-600); }
.fb-select.open .fb-select__btn::after { transform: rotate(180deg); }
.fb-select__list {
  position: absolute; top: calc(100% + 6px); left: 0; right: 0; z-index: 30;
  margin: 0; padding: 6px; list-style: none;
  background: var(--paper-surface); border: 1px solid var(--ink-200);
  border-radius: var(--radius-md); box-shadow: var(--shadow-md); display: none;
}
.fb-select.open .fb-select__list { display: block; }
.fb-select__opt {
  padding: 10px 12px; border-radius: var(--radius-sm); font-size: 14px;
  color: var(--ink-700); cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast);
}
.fb-select__opt:hover { background: var(--paper-page); color: var(--brand-600); }
.fb-select__opt.is-active { color: var(--brand-600); font-weight: 600; }

/* ---------- 一起做页 ---------- */
.join-hero-preview { text-align: center; padding: 16px 0 0; }
.join-hero-preview img.join-big { height: 44px; margin: 0 auto 12px; display: block; }
.join-hero-preview .slogan { font-size: 22px; font-weight: 700; }
.join-hero-preview .sub { font-size: 15px; color: var(--ink-700); max-width: 620px; margin: 12px auto 0; }
.extra-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-top: 24px; }
.extra-grid h3 { font-size: 15px; font-weight: 600; margin-bottom: 6px; }
.extra-grid p { font-size: 13px; color: var(--ink-700); }
.dev-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-top: 32px; }
.dev-card h4 { font-size: 15px; font-weight: 600; margin-bottom: 8px; }
.dev-card .do { font-size: 13px; color: var(--ink-700); }
.dev-card .skill { font-size: 12px; color: var(--ink-700); margin-top: 8px; }
.dev-card .skill b { color: var(--ink-900); }
.dev-card .major { font-size: 12px; color: var(--ink-500); margin-top: 4px; }
.dev-note { margin-top: 20px; font-size: 14px; color: var(--ink-700); }
.role-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 24px; }
.way-card .col h5 { font-size: 13px; font-weight: 600; color: var(--ink-700); margin-bottom: 8px; }
.way-card .col ul { list-style: none; }
.way-card .col li {
  font-size: 14px; color: var(--ink-700); padding: 5px 0 5px 16px; position: relative;
}
.way-card .col li::before {
  content: ""; position: absolute; left: 0; top: 13px; width: 5px; height: 5px;
  border-radius: var(--radius-full); background: var(--brand-600);
}
.honest-card {
  background: var(--ink-100); border: 1px solid var(--ink-200);
  border-radius: var(--radius-lg); padding: 28px;
}
.honest-card h3 { font-size: 17px; margin-bottom: 10px; }
.honest-card p { font-size: 14px; color: var(--ink-700); margin-top: 6px; }
.join-ways { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 24px; }
.qq-card { text-align: center; padding: 28px 24px; display: flex; flex-direction: column; align-items: center; }
.qq-card .h { font-size: 13px; font-weight: 600; color: var(--ink-700); }
.qq-card .gnum { font-size: 28px; font-weight: 700; margin: 8px 0 14px; }
.qq-card .hint { font-size: 12px; color: var(--ink-500); margin-top: 10px; }

/* ---------- 大 CTA ---------- */
.big-cta { text-align: center; padding: 72px 0; }
.big-cta h2 { font-size: 30px; }
.big-cta .ver { font-size: 13px; color: var(--ink-500); margin-top: 16px; }
.big-cta .btn { margin-top: 24px; }

/* ---------- 滚动淡入（js/main.js 自动挂载） ---------- */
.reveal { opacity: 0; transform: translateY(14px); transition: opacity 280ms cubic-bezier(0.2, 0, 0, 1), transform 280ms cubic-bezier(0.2, 0, 0, 1); }
.reveal.visible { opacity: 1; transform: none; }
.reveal-d1 { transition-delay: 40ms; }
.reveal-d2 { transition-delay: 80ms; }
.reveal-d3 { transition-delay: 120ms; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  .cursor { animation: none; }
  html { scroll-behavior: auto; }
}

/* ---------- 管理页（admin.html 局部补充） ---------- */
.admin-note { font-size: 12px; color: var(--ink-500); line-height: 1.7; margin-top: 12px; }

/* ---------- 响应式：960 / 600 ---------- */
@media (max-width: 960px) {
  .hero h1 { font-size: 34px; }
  .feature-row, .feature-row.rev { grid-template-columns: 1fr; }
  .feature-row.rev .desc { order: 0; }
  .minifeats { grid-template-columns: repeat(2, 1fr); }
  .trust-grid, .form-2col, .join-ways, .role-grid { grid-template-columns: 1fr; }
  .channel-grid { grid-template-columns: 1fr; }
  .howto-grid { grid-template-columns: 1fr; }
  .loop-grid { grid-template-columns: 1fr 1fr; }
  .dev-grid { grid-template-columns: 1fr 1fr; }
  .extra-grid { grid-template-columns: 1fr; }
  .req-list { grid-template-columns: 1fr; }
  .desk-grid { grid-template-columns: 1fr; }
}
@media (max-width: 600px) {
  .section { padding: 40px 0; }
  .nav-links {
    display: none;
    position: absolute; top: 60px; left: 0; right: 0;
    flex-direction: column; align-items: flex-start; gap: 4px;
    background: var(--paper-surface); border-bottom: 1px solid var(--ink-200);
    padding: 12px 20px 16px; box-shadow: var(--shadow-md);
  }
  .nav-links.open { display: flex; }
  .nav-links > a { padding: 8px 0; }
  .nav-burger { display: block; }
  .hero { padding: 44px 0; }
  .hero h1 { font-size: 29px; }
  .hero .sub { font-size: 15px; }
  .stats-band { grid-template-columns: 1fr; }
  .minifeats, .loop-grid, .dev-grid { grid-template-columns: 1fr; }
  .section-title { font-size: 20px; }
  .appframe { grid-template-columns: 40px 1fr; }
  .app-side { padding: 8px 0; }
  .side-ico { width: 26px; height: 26px; }
  .side-ico span.lab { display: none; }
  .ff-body { padding: 12px; }
  .answer-row { flex-direction: column; }
  .answer-row .btn { width: 100%; }
  .wb-group { flex-wrap: wrap; }
  .btn-lg { width: 100%; }
  .hero-cta { flex-direction: column; align-items: stretch; }
  .hero-version { text-align: center; }
  .channel-card .btn { width: 100%; }
  .flash-actions { flex-direction: column; }
  .fb-form .btn[type="submit"], .fb-form .btn-lg { width: 100%; }
}