/* ============================================================
   纸飞机 · 对话窗口  zhifeijiios.com
   电报蓝 #2aabee · 聊天浅灰底 · 左侧会话列表 + 聊天窗口 hero
   ============================================================ */
:root {
  --bg: #f0f4f7;
  --bg-2: #e9eef2;
  --surface: #ffffff;
  --ink: #17212b;
  --ink-soft: #3d4b58;
  --muted: #6c7883;
  --line: #dde5ea;
  --brand: #2aabee;
  --brand-dark: #1c93d6;
  --brand-light: #4db8f2;
  --brand-soft: #e3f4fc;
  --bubble-in: #e7f5fd;
  --online: #4fd08a;
  --accent: #f5a623;
  --accent-soft: #fdf3df;
  --radius: 18px;
  --radius-sm: 12px;
  --shadow-sm: 0 1px 2px rgba(23, 33, 43, .04), 0 6px 18px rgba(23, 33, 43, .05);
  --shadow-md: 0 16px 44px rgba(23, 33, 43, .12);
  --shadow-brand: 0 12px 28px rgba(42, 171, 238, .30);
  --font-sans: "Segoe UI", "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, -apple-system, sans-serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  font-family: var(--font-sans);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
a:hover { color: var(--brand); }
img { max-width: 100%; display: block; }
svg { display: block; }

.container { max-width: 1120px; margin: 0 auto; padding: 0 40px; }
.wide { max-width: 1280px; }

/* ---------- 应用外壳:左侧会话列表 + 主区 ---------- */
.app { display: flex; min-height: 100vh; }
.main { flex: 1; min-width: 0; margin-left: 260px; }

/* ---------- 左侧会话列表侧栏 ---------- */
.sidebar {
  position: fixed; top: 0; left: 0; bottom: 0; width: 260px; z-index: 70;
  background: var(--surface); border-right: 1px solid var(--line);
  display: flex; flex-direction: column; padding: 22px 14px 18px;
}
.side-brand { padding: 0 8px 18px; border-bottom: 1px solid var(--line); margin-bottom: 14px; }
.brand { display: flex; align-items: center; gap: 11px; font-weight: 800; font-size: 1.1rem; letter-spacing: .3px; }
.logo-mark { width: 34px; height: 34px; flex: 0 0 auto; border-radius: 50%; object-fit: cover; display: block; }
.logo-mark.sm { width: 26px; height: 26px; }
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand .brand-tag { font-size: .62rem; font-weight: 700; color: var(--muted); letter-spacing: 3px; margin-top: 2px; }
.side-label { font-size: .7rem; font-weight: 800; color: var(--muted); letter-spacing: 2px; text-transform: uppercase; padding: 0 10px 8px; }
.chat-nav { display: flex; flex-direction: column; gap: 3px; flex: 1; overflow-y: auto; }
.chat-item {
  display: flex; align-items: center; gap: 11px;
  padding: 10px 12px; border-radius: 13px; transition: background .14s ease;
}
.chat-item:hover { background: var(--bg); }
.chat-item .avatar {
  width: 40px; height: 40px; flex: 0 0 auto; border-radius: 50%;
  background: var(--brand-soft); color: var(--brand);
  display: grid; place-items: center;
}
.chat-item .avatar svg { width: 20px; height: 20px; }
.chat-item .chat-meta { display: flex; flex-direction: column; min-width: 0; }
.chat-item .chat-name { font-size: .93rem; font-weight: 700; color: var(--ink); line-height: 1.25; }
.chat-item .chat-preview { font-size: .76rem; color: var(--muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.chat-item.active { background: var(--brand); color: #fff; box-shadow: var(--shadow-brand); }
.chat-item.active:hover { background: var(--brand); }
.chat-item.active .avatar { background: rgba(255,255,255,.2); color: #fff; }
.chat-item.active .chat-name { color: #fff; }
.chat-item.active .chat-preview { color: rgba(255,255,255,.85); }
.side-cta { margin-top: 14px; padding: 0 6px; }
.side-cta .btn { width: 100%; justify-content: center; }

/* ---------- 顶栏 ---------- */
.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 14px;
  background: rgba(255,255,255,.82);
  backdrop-filter: saturate(1.1) blur(14px);
  -webkit-backdrop-filter: saturate(1.1) blur(14px);
  border-bottom: 1px solid var(--line); padding: 12px 30px;
}
.hamburger { display: none; background: none; border: 0; cursor: pointer; color: var(--ink); width: 40px; height: 40px; border-radius: 10px; place-items: center; }
.hamburger svg { width: 22px; height: 22px; }
.topbar-search {
  flex: 1; max-width: 420px; display: flex; align-items: center; gap: 9px;
  background: var(--bg); color: var(--muted); font-size: .9rem;
  padding: 9px 16px; border-radius: 999px; border: 1px solid transparent;
}
.topbar-search svg { width: 16px; height: 16px; }
.topbar-search:hover { border-color: var(--brand); color: var(--ink); }
.topbar-cta { margin-left: auto; }

/* ---------- Hero ---------- */
.hero { padding: 46px 0 54px; background: linear-gradient(180deg, #e7f4fb 0%, var(--bg) 100%); }
.hero-inner {
  display: grid; grid-template-columns: 1.05fr .95fr; gap: 40px; align-items: center;
}
.hero-copy { min-width: 0; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--brand-soft); color: var(--brand-dark);
  font-size: .8rem; font-weight: 800; padding: 6px 16px; border-radius: 999px;
  letter-spacing: 1px; margin-bottom: 20px;
}
.eyebrow svg { width: 15px; height: 15px; }
.hero h1 { font-size: clamp(1.9rem, 3.6vw, 2.7rem); line-height: 1.16; font-weight: 800; letter-spacing: -.6px; }
.hero h1 .hl { background: linear-gradient(100deg, var(--brand-dark), var(--brand)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero .lead { color: var(--ink-soft); font-size: 1.07rem; margin: 20px 0 28px; max-width: 32em; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; }
.btn {
  display: inline-flex; align-items: center; gap: 9px;
  padding: 13px 26px; border-radius: 999px; font-weight: 800; font-size: .96rem;
  border: 1px solid transparent; cursor: pointer; transition: transform .14s ease, box-shadow .14s ease, background .14s ease;
}
.btn svg { width: 17px; height: 17px; }
.btn:hover { transform: translateY(-3px); }
.btn-primary { background: linear-gradient(135deg, var(--brand), var(--brand-dark)); color: #fff; box-shadow: var(--shadow-brand); }
.btn-primary:hover { color: #fff; box-shadow: 0 18px 40px rgba(42, 171, 238, .42); }
.btn-ghost { background: var(--surface); color: var(--ink); border-color: var(--line); box-shadow: var(--shadow-sm); }
.btn-ghost:hover { border-color: var(--brand); color: var(--brand); }
.hero-meta { display: flex; flex-wrap: wrap; gap: 20px; margin-top: 26px; font-size: .86rem; color: var(--muted); }
.hero-meta span { display: inline-flex; align-items: center; gap: 6px; }
.hero-meta svg { width: 16px; height: 16px; color: var(--brand); }
.hero-art { display: grid; place-items: center; }
.hero-art svg { width: min(290px, 100%); height: auto; }

/* ---------- 聊天窗口面板 ---------- */
.chat-panel {
  background: var(--surface); border: 1px solid var(--line); border-radius: 20px;
  box-shadow: var(--shadow-md); overflow: hidden; display: flex; flex-direction: column;
}
.chat-head { display: flex; align-items: center; gap: 12px; padding: 14px 16px; border-bottom: 1px solid var(--line); background: var(--surface); }
.chat-head .avatar { width: 42px; height: 42px; flex: 0 0 auto; border-radius: 50%; background: var(--brand-soft); color: var(--brand); display: grid; place-items: center; }
.chat-head .avatar svg { width: 21px; height: 21px; }
.chat-head .av-brand { background: linear-gradient(135deg, var(--brand), var(--brand-dark)); color: #fff; }
.chat-head-meta { display: flex; flex-direction: column; line-height: 1.2; }
.chat-head .chat-name { font-size: .98rem; font-weight: 800; }
.chat-status { font-size: .78rem; color: var(--muted); display: flex; align-items: center; gap: 6px; }
.online-dot { width: 8px; height: 8px; border-radius: 50%; background: var(--online); }
.chat-body { padding: 18px 16px; display: flex; flex-direction: column; gap: 12px; background: linear-gradient(180deg, #f6fafd, #eef4f8); min-height: 300px; }
.bubble { max-width: 82%; display: flex; }
.bubble .msg { padding: 11px 15px; border-radius: 16px; font-size: .92rem; line-height: 1.55; }
.bubble.in { align-self: flex-start; }
.bubble.in .msg { background: var(--bubble-in); color: var(--ink); border-bottom-left-radius: 5px; }
.bubble.out { align-self: flex-end; }
.bubble.out .msg { background: linear-gradient(135deg, var(--brand), var(--brand-dark)); color: #fff; border-bottom-right-radius: 5px; }
.bubble.typing { align-self: flex-start; background: var(--bubble-in); border-radius: 16px; border-bottom-left-radius: 5px; padding: 13px 15px; gap: 5px; }
.bubble.typing .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--brand); opacity: .5; animation: blink 1.2s infinite; }
.bubble.typing .dot:nth-child(2) { animation-delay: .2s; }
.bubble.typing .dot:nth-child(3) { animation-delay: .4s; }
@keyframes blink { 0%, 60%, 100% { opacity: .25; } 30% { opacity: 1; } }
.chat-foot { display: flex; align-items: center; gap: 10px; padding: 12px 14px; border-top: 1px solid var(--line); }
.input-bar { flex: 1; background: var(--bg); border-radius: 999px; padding: 10px 18px; }
.input-hint { color: var(--muted); font-size: .9rem; }
.send-btn {
  width: 42px; height: 42px; flex: 0 0 auto; border-radius: 50%;
  background: linear-gradient(135deg, var(--brand), var(--brand-dark)); color: #fff;
  display: grid; place-items: center; box-shadow: var(--shadow-brand);
}
.send-btn svg { width: 20px; height: 20px; }
.send-btn:hover { color: #fff; transform: translateY(-2px); }

/* ---------- 通用 section ---------- */
.section { padding: 62px 0; }
.section.alt { background: linear-gradient(180deg, var(--bg-2), var(--bg)); }
.section-head { max-width: 640px; margin-bottom: 34px; }
.section-head.centered { margin-left: auto; margin-right: auto; text-align: center; }
.kicker { color: var(--brand); font-weight: 800; font-size: .8rem; letter-spacing: 3px; text-transform: uppercase; margin-bottom: 8px; }
.section-head h2 { font-size: clamp(1.5rem, 2.8vw, 1.95rem); font-weight: 800; letter-spacing: -.4px; }
.section-head p { color: var(--muted); margin-top: 10px; }

/* ---------- 功能网格(bento) ---------- */
.bento { display: grid; grid-template-columns: repeat(12, 1fr); gap: 18px; }
.bento .cell {
  grid-column: span 4; background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 26px 24px; box-shadow: var(--shadow-sm);
  position: relative; overflow: hidden;
}
.bento .cell:nth-child(1) { grid-column: span 7; }
.bento .cell:nth-child(2) { grid-column: span 5; }
.bento .cell:nth-child(3) { grid-column: span 5; }
.bento .cell:nth-child(4) { grid-column: span 7; }
.bento .cell:nth-child(5) { grid-column: span 6; }
.bento .cell:nth-child(6) { grid-column: span 6; }
.bento .cell.large { grid-column: span 7; }
.bento .cell .ico { width: 48px; height: 48px; border-radius: 50%; display: grid; place-items: center; margin-bottom: 16px; color: var(--brand); background: var(--brand-soft); }
.bento .cell .ico svg { width: 24px; height: 24px; }
.bento .cell h3 { font-size: 1.1rem; font-weight: 800; margin-bottom: 8px; }
.bento .cell p { color: var(--muted); font-size: .94rem; }
.bento .cell .cell-img { width: 100%; height: 100px; object-fit: cover; border-radius: var(--radius-sm); margin-top: 18px; box-shadow: var(--shadow-sm); }
.bento .cell::after { content: ""; position: absolute; top: -40px; right: -40px; width: 120px; height: 120px; background: radial-gradient(circle, rgba(42,171,238,.10), transparent 70%); }

/* ---------- 横向滚动步骤卡 ---------- */
.hscroll { display: grid; grid-auto-flow: column; grid-auto-columns: 260px; gap: 18px; overflow-x: auto; padding: 6px 2px 18px; scroll-snap-type: x mandatory; }
.hscroll::-webkit-scrollbar { height: 8px; }
.hscroll::-webkit-scrollbar-thumb { background: var(--line); border-radius: 8px; }
.route-card { scroll-snap-align: start; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px 20px; box-shadow: var(--shadow-sm); position: relative; }
.route-card .num { display: inline-grid; place-items: center; width: 34px; height: 34px; border-radius: 50%; background: linear-gradient(135deg, var(--brand), var(--brand-dark)); color: #fff; font-weight: 800; font-size: .95rem; margin-bottom: 14px; }
.route-card h3 { font-size: 1.02rem; font-weight: 800; margin-bottom: 6px; }
.route-card p { color: var(--muted); font-size: .88rem; }

/* ---------- 平台卡 ---------- */
.platforms { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.plat-card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow-sm); transition: transform .16s ease, box-shadow .16s ease; }
.plat-card:hover { transform: translateY(-5px); box-shadow: var(--shadow-md); }
.plat-card .plat-body { padding: 24px; }
.plat-card .ico { width: 50px; height: 50px; border-radius: 50%; display: grid; place-items: center; background: var(--brand-soft); color: var(--brand); margin-bottom: 14px; }
.plat-card .ico svg { width: 25px; height: 25px; }
.plat-card h3 { font-size: 1.08rem; font-weight: 800; }
.plat-card p { color: var(--muted); font-size: .88rem; margin: 7px 0 16px; min-height: 42px; }
.plat-card span { color: var(--brand); font-weight: 800; font-size: .9rem; }
.platforms-band { position: relative; }
.platforms-band::before { content: ""; position: absolute; inset: 0; background: url(../images/paper-plane-sky.jpg) center/cover no-repeat; }
.platforms-band::after { content: ""; position: absolute; inset: 0; background: linear-gradient(180deg, rgba(240,244,247,.92) 0%, rgba(240,244,247,.76) 55%, rgba(240,244,247,.92) 100%); }
.platforms-band .container { position: relative; z-index: 1; }

/* ---------- 步骤 ---------- */
.steps { counter-reset: step; display: grid; gap: 0; }
.step { position: relative; padding: 0 0 26px 60px; }
.step::before { counter-increment: step; content: counter(step); position: absolute; left: 0; top: 0; width: 42px; height: 42px; border-radius: 50%; background: linear-gradient(135deg, var(--brand), var(--brand-dark)); color: #fff; font-weight: 800; display: grid; place-items: center; box-shadow: var(--shadow-brand); }
.step::after { content: ""; position: absolute; left: 20px; top: 46px; bottom: 4px; width: 2px; background: linear-gradient(var(--brand), transparent); }
.step:last-child::after { display: none; }
.step h3 { font-size: 1.05rem; font-weight: 800; margin-bottom: 6px; }
.step p { color: var(--muted); font-size: .94rem; }

/* ---------- 左右图文 split ---------- */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: center; }
.split-media { position: relative; }
.split-media img { border-radius: var(--radius); box-shadow: var(--shadow-md); aspect-ratio: 4/3; object-fit: cover; width: 100%; }
.split h3 { font-size: 1.5rem; font-weight: 800; margin-bottom: 12px; letter-spacing: -.3px; }
.split p { color: var(--ink-soft); margin-bottom: 12px; }
.split .tag { display: inline-block; background: var(--brand-soft); color: var(--brand-dark); font-size: .76rem; font-weight: 800; padding: 5px 14px; border-radius: 999px; margin-bottom: 14px; }

/* ---------- 表格 ---------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); box-shadow: var(--shadow-sm); }
table { width: 100%; border-collapse: collapse; font-size: .94rem; }
th, td { padding: 14px 18px; text-align: left; border-bottom: 1px solid var(--line); }
th { background: var(--bg-2); font-weight: 800; color: var(--ink-soft); }
tr:last-child td { border-bottom: 0; }
td.hl { color: var(--brand); font-weight: 800; }

/* ---------- 提示/警示 ---------- */
.tip, .callout { border-radius: var(--radius-sm); padding: 14px 18px; margin: 16px 0; font-size: .94rem; display: flex; gap: 11px; align-items: flex-start; }
.tip { background: var(--brand-soft); border: 1px solid #c7e9fb; color: #1373ac; }
.callout { background: var(--accent-soft); border: 1px solid #f2e0b8; color: #8a6414; }
.tip::before, .callout::before { content: "!"; flex: 0 0 auto; width: 20px; height: 20px; border-radius: 50%; background: currentColor; color: #fff; display: grid; place-items: center; font-size: .78rem; font-weight: 800; margin-top: 3px; }

/* ---------- FAQ 折叠 ---------- */
.faq-list { display: grid; gap: 12px; }
.faq-item { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-sm); overflow: hidden; box-shadow: var(--shadow-sm); }
.faq-item summary { list-style: none; cursor: pointer; padding: 17px 22px; font-weight: 800; display: flex; justify-content: space-between; align-items: center; gap: 14px; }
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after { content: "+"; font-size: 1.4rem; color: var(--brand); font-weight: 400; line-height: 1; }
.faq-item[open] summary::after { content: "–"; }
.faq-item .faq-a { padding: 0 22px 18px; color: var(--ink-soft); font-size: .95rem; }

/* ---------- 面包屑 ---------- */
.crumbs { font-size: .86rem; color: var(--muted); padding: 20px 0 4px; display: flex; flex-wrap: wrap; gap: 6px; }
.crumbs a { color: var(--muted); }
.crumbs a:hover { color: var(--brand); }
.crumbs .sep { opacity: .5; }

/* ---------- 文章双栏 ---------- */
.article-wrap { display: grid; grid-template-columns: 1fr 270px; gap: 40px; padding: 30px 0 60px; }
.article-body h2 { font-size: 1.45rem; font-weight: 800; margin: 34px 0 12px; letter-spacing: -.3px; }
.article-body h2:first-of-type { margin-top: 10px; }
.article-body h3 { font-size: 1.12rem; font-weight: 800; margin: 22px 0 8px; }
.article-body p { color: var(--ink-soft); margin: 12px 0; }
.article-body img { border-radius: var(--radius); margin: 22px 0; box-shadow: var(--shadow-md); width: 94%; }
.article-body ul, .article-body ol { margin: 12px 0 12px 22px; color: var(--ink-soft); }
.article-body li { margin: 6px 0; }
.article-body .cap { font-size: .82rem; color: var(--muted); text-align: center; margin-top: -14px; }
.article-intro { font-size: 1.08rem; color: var(--ink-soft); border-left: 3px solid var(--brand); padding-left: 18px; margin: 14px 0 22px; }
.toc { position: sticky; top: 90px; align-self: start; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow-sm); }
.toc h4 { font-size: .82rem; letter-spacing: 1px; color: var(--muted); margin-bottom: 12px; text-transform: uppercase; }
.toc a { display: block; font-size: .9rem; color: var(--ink-soft); padding: 6px 0; border-left: 2px solid var(--line); padding-left: 12px; }
.toc a:hover { color: var(--brand); border-left-color: var(--brand); }

/* ---------- 相关卡片 ---------- */
.related { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-top: 8px; }
.rel-card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 18px; box-shadow: var(--shadow-sm); transition: transform .15s ease; }
.rel-card:hover { transform: translateY(-4px); }
.rel-card .cat { font-size: .74rem; color: var(--brand); font-weight: 800; letter-spacing: 1px; text-transform: uppercase; }
.rel-card h4 { font-size: .98rem; font-weight: 800; margin: 6px 0; }
.rel-card p { color: var(--muted); font-size: .84rem; }

/* ---------- 页脚 ---------- */
.site-footer { background: var(--ink); color: #c4d0d9; padding: 56px 0 28px; }
.site-footer a { color: #c4d0d9; }
.site-footer a:hover { color: #fff; }
.foot-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 30px; }
.foot-brand { display: flex; align-items: center; gap: 10px; color: #fff; font-weight: 800; font-size: 1.1rem; margin-bottom: 12px; }
.foot-about { font-size: .88rem; color: #9fb0bc; max-width: 30em; }
.foot-col h4 { color: #fff; font-size: .92rem; margin-bottom: 14px; }
.foot-col a { display: block; font-size: .88rem; padding: 4px 0; color: #9fb0bc; }
.foot-col a:hover { color: #fff; }
.foot-bottom { border-top: 1px solid #2c3a46; margin-top: 34px; padding-top: 20px; font-size: .84rem; color: #7e8f9b; text-align: center; }

/* ---------- 返回顶部 ---------- */
.to-top { position: fixed; right: 22px; bottom: 24px; width: 46px; height: 46px; border-radius: 50%; background: linear-gradient(135deg, var(--brand), var(--brand-dark)); color: #fff; display: grid; place-items: center; box-shadow: var(--shadow-brand); opacity: 0; pointer-events: none; transition: opacity .2s; z-index: 60; border: 0; cursor: pointer; }
.to-top.show { opacity: 1; pointer-events: auto; }
.to-top:hover { color: #fff; }

/* ---------- CTA band ---------- */
.cta-band { background: linear-gradient(120deg, var(--brand), var(--brand-dark)); color: #fff; border-radius: var(--radius); padding: 44px 42px; display: flex; flex-wrap: wrap; align-items: center; gap: 24px; justify-content: space-between; box-shadow: var(--shadow-brand); }
.cta-band h3 { font-size: 1.5rem; font-weight: 800; }
.cta-band p { opacity: .92; margin-top: 6px; }
.cta-band .btn { background: #fff; color: var(--brand-dark); }
.cta-band .btn:hover { color: var(--brand-dark); }

/* ---------- 404 / 搜索 / sitemap ---------- */
.empty-state { text-align: center; padding: 90px 0; }
.empty-state h1 { font-size: 3rem; font-weight: 800; color: var(--brand); }
.empty-state p { color: var(--muted); margin: 14px 0 24px; }
.search-box { display: flex; gap: 10px; max-width: 520px; margin: 0 auto 30px; }
.search-box input { flex: 1; padding: 13px 20px; border: 1px solid var(--line); border-radius: 999px; font-size: 1rem; font-family: inherit; background: var(--surface); }
.search-box input:focus { outline: 2px solid var(--brand); border-color: transparent; }
.sitemap-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.sitemap-grid a { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 12px 18px; font-size: .92rem; box-shadow: var(--shadow-sm); }
.sitemap-grid a:hover { border-color: var(--brand); color: var(--brand); }

/* ---------- 响应式 ---------- */
@media (max-width: 1080px) {
  .main { margin-left: 0; }
  .sidebar { transform: translateX(-100%); transition: transform .22s ease; box-shadow: var(--shadow-md); }
  .sidebar.open { transform: translateX(0); }
  .hamburger { display: grid; }
  .topbar-cta { margin-left: 0; }
}
@media (max-width: 900px) {
  .hero-inner { grid-template-columns: 1fr; padding: 0; }
  .hero-art, .chat-panel { order: -1; }
  .hero-art svg { width: 200px; }
  .bento { grid-template-columns: 1fr 1fr; }
  .bento .cell, .bento .cell:nth-child(n) { grid-column: span 1; }
  .bento .cell.large, .bento .cell:nth-child(1) { grid-column: span 2; }
  .platforms { grid-template-columns: 1fr 1fr; }
  .split { grid-template-columns: 1fr; gap: 26px; }
  .article-wrap { grid-template-columns: 1fr; }
  .toc { position: static; }
  .related { grid-template-columns: 1fr 1fr; }
  .foot-grid { grid-template-columns: 1fr 1fr; }
  .sitemap-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 620px) {
  .container { padding: 0 20px; }
  .bento, .platforms, .related, .sitemap-grid { grid-template-columns: 1fr; }
  .bento .cell, .bento .cell:nth-child(n), .bento .cell.large { grid-column: span 1; }
  .cta-band { padding: 30px 24px; }
  .topbar { padding: 10px 16px; }
  .topbar-search { display: none; }
}