/* 从单页版提取的原样式（设计令牌 / 排版 / 组件 / 响应式） */
/* ============================================================
   Codex 从入门到专精 · 单文件站点样式
   设计取向：Dark Mode (OLED) + Swiss 极简 + Aurora 极光点缀
   原则：零外部请求（不引字体/CDN）、内容静态输出、动效可降级
   ============================================================ */

/* ---------- 1. 设计令牌 ---------- */
:root{
  color-scheme:dark;
  --bg:#070A12; --bg-2:#0A0F1B;
  --surface:#0F1626; --surface-2:#141D30; --surface-3:#1A2438;
  --border:#1F2A3D; --border-soft:#172136;
  --fg:#E9EFFA; --fg-2:#BAC6DB; --fg-3:#8FA0BC;
  --fg-fade:rgba(233,239,250,.62);
  --brand:#31D9A8; --brand-2:#5CA8FF; --brand-3:#B184FF;
  --ok:#34D399; --warn:#FBBF24; --danger:#F87171;
  --ring:#5CA8FF;
  --shadow:0 20px 44px -26px rgba(0,0,0,.95);
  --glow:0 0 0 1px rgba(255,255,255,.03),0 24px 60px -30px rgba(49,217,168,.35);
  --r-sm:10px; --r:16px; --r-lg:24px;
  --sp1:8px; --sp2:16px; --sp3:24px; --sp4:32px; --sp5:48px; --sp6:72px;
  --sans:system-ui,-apple-system,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans SC",sans-serif;
  --mono:ui-monospace,SFMono-Regular,"SF Mono","Cascadia Code","JetBrains Mono",Consolas,"Liberation Mono",monospace;
  --maxw:1320px;
}
:root[data-theme=light]{
  color-scheme:light;
  --bg:#F5F7FB; --bg-2:#EDF1F8;
  --surface:#FFFFFF; --surface-2:#F5F8FD; --surface-3:#EEF3FB;
  --border:#DCE4F0; --border-soft:#E7EDF7;
  --fg:#0D1524; --fg-2:#3A4862; --fg-3:#5A6B87;
  --fg-fade:rgba(13,21,36,.72);
  --brand:#0B8F68; --brand-2:#2563EB; --brand-3:#7C3AED;
  --ok:#047857; --warn:#A8560A; --danger:#B42318;
  --ring:#2563EB;
  --shadow:0 18px 40px -30px rgba(15,23,42,.45);
  --glow:0 0 0 1px rgba(15,23,42,.04),0 20px 44px -32px rgba(11,143,104,.45);
}

/* ---------- 2. 基础 ---------- */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;scroll-padding-top:92px}
body{
  margin:0;background:var(--bg);color:var(--fg);
  font:400 16px/1.75 var(--sans);
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
  overflow-x:hidden;
}
img,svg{max-width:100%}
a{color:var(--brand-2);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3,h4{line-height:1.3;margin:0;font-weight:700;letter-spacing:-.01em}
p{margin:0 0 var(--sp2)}
ul,ol{margin:0 0 var(--sp2);padding-left:1.35em}
li{margin:.35em 0}
code,kbd,pre{font-family:var(--mono)}
:not(pre)>code{
  background:var(--surface-3);border:1px solid var(--border-soft);
  padding:.12em .42em;border-radius:6px;font-size:.9em;color:var(--fg);
  word-break:break-word;
}
strong{color:var(--fg);font-weight:700}
hr{border:0;border-top:1px solid var(--border);margin:var(--sp4) 0}
:focus-visible{outline:2px solid var(--ring);outline-offset:3px;border-radius:6px}
::selection{background:rgba(49,217,168,.28)}
.ic{width:1em;height:1em;flex:none;fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}
.sr{position:absolute!important;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0}
.skip{position:absolute;left:50%;translate:-50% -140%;z-index:99;background:var(--brand);color:#04140E;padding:.7em 1.2em;border-radius:0 0 12px 12px;font-weight:700;transition:translate .18s}
.skip:focus{translate:-50% 0}

/* ---------- 3. 顶栏 ---------- */
.progress{position:fixed;inset:0 0 auto 0;height:3px;z-index:60;background:transparent}
.progress i{display:block;height:100%;width:100%;transform:scaleX(0);transform-origin:0 50%;
  background:linear-gradient(90deg,var(--brand),var(--brand-2) 55%,var(--brand-3))}
.topbar{
  position:fixed;inset:0 0 auto 0;z-index:50;height:64px;
  display:flex;align-items:center;gap:12px;padding:0 clamp(14px,3vw,28px);
  background:var(--bg);
  background:color-mix(in srgb,var(--bg) 82%,transparent);
  backdrop-filter:blur(14px) saturate(1.3);
  border-bottom:1px solid var(--border-soft);
}
@supports not (backdrop-filter:blur(4px)){.topbar{background:var(--bg)}}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;letter-spacing:-.02em;color:var(--fg);white-space:nowrap}
.brand:hover{text-decoration:none}
.brand .mark{
  width:32px;height:32px;border-radius:10px;display:grid;place-items:center;flex:none;
  background:linear-gradient(140deg,var(--brand),var(--brand-2));color:#04140E;font-size:17px;
  box-shadow:0 8px 20px -10px rgba(49,217,168,.9);
}
.brand b{font-size:16px}
.brand small{display:block;font-size:11px;font-weight:600;color:var(--fg-3);letter-spacing:.06em}
.topnav{display:flex;gap:4px;margin-left:auto;align-items:center}
.topnav a{
  color:var(--fg-2);font-size:14px;font-weight:600;padding:8px 12px;border-radius:9px;
  transition:background .18s,color .18s;white-space:nowrap;
}
.topnav a:hover{background:var(--surface-2);color:var(--fg);text-decoration:none}
.iconbtn{
  width:40px;height:40px;display:grid;place-items:center;flex:none;cursor:pointer;
  background:var(--surface-2);border:1px solid var(--border);color:var(--fg-2);
  border-radius:11px;font-size:18px;transition:color .18s,border-color .18s,translate .18s;
}
.iconbtn:hover{color:var(--fg);border-color:var(--brand)}
.iconbtn:active{translate:0 1px}
#tocBtn{display:none}

/* ---------- 4. 首屏 ---------- */
.hero{
  position:relative;overflow:hidden;isolation:isolate;
  padding:calc(64px + clamp(48px,8vw,90px)) clamp(14px,3vw,28px) clamp(40px,6vw,72px);
  border-bottom:1px solid var(--border-soft);
}
.aurora{position:absolute;inset:-30% -10% 0;z-index:-2;filter:blur(58px);opacity:.62;pointer-events:none}
.aurora i{position:absolute;display:block;border-radius:50%;mix-blend-mode:screen;animation:drift 26s ease-in-out infinite}
.aurora i:nth-child(1){width:46vw;height:46vw;left:-6vw;top:-4vw;background:radial-gradient(circle at 30% 30%,#1E8F73,#0B4D3F 60%,transparent 72%)}
.aurora i:nth-child(2){width:40vw;height:40vw;right:-4vw;top:-8vw;background:radial-gradient(circle at 60% 40%,#1B4E9B,#0A2050 62%,transparent 74%);animation-duration:31s;animation-delay:-8s}
.aurora i:nth-child(3){width:34vw;height:34vw;left:34%;top:16vw;background:radial-gradient(circle at 50% 50%,#5B2E9E,#1B0F3A 60%,transparent 72%);animation-duration:37s;animation-delay:-16s}
:root[data-theme=light] .aurora{opacity:.4;filter:blur(64px)}
:root[data-theme=light] .aurora i:nth-child(1){background:radial-gradient(circle at 30% 30%,#7FE6C4,#CFEFE4 60%,transparent 72%)}
:root[data-theme=light] .aurora i:nth-child(2){background:radial-gradient(circle at 60% 40%,#A9C6FF,#DDE8FF 62%,transparent 74%)}
:root[data-theme=light] .aurora i:nth-child(3){background:radial-gradient(circle at 50% 50%,#D5BDFF,#EEE6FF 60%,transparent 72%)}
.gridlines{position:absolute;inset:0;z-index:-1;pointer-events:none;opacity:.5;
  background-image:linear-gradient(to right,rgba(140,160,190,.12) 1px,transparent 1px),linear-gradient(to bottom,rgba(140,160,190,.12) 1px,transparent 1px);
  background-size:64px 64px;
  mask-image:radial-gradient(ellipse 80% 70% at 50% 20%,#000 30%,transparent 78%);
  -webkit-mask-image:radial-gradient(ellipse 80% 70% at 50% 20%,#000 30%,transparent 78%);
}
@keyframes drift{
  0%,100%{transform:translate3d(0,0,0) scale(1)}
  33%{transform:translate3d(3vw,2vw,0) scale(1.08)}
  66%{transform:translate3d(-2vw,-3vw,0) scale(.95)}
}
.hero-in{max-width:var(--maxw);margin:0 auto;display:grid;grid-template-columns:minmax(0,1.08fr) minmax(0,.92fr);gap:clamp(28px,5vw,64px);align-items:center}
.pill{
  display:inline-flex;align-items:center;gap:8px;font-size:13px;font-weight:600;color:var(--fg-2);
  background:var(--surface-2);border:1px solid var(--border);border-radius:999px;padding:7px 14px;margin-bottom:var(--sp3);
}
.pill .dot{width:7px;height:7px;border-radius:50%;background:var(--brand);box-shadow:0 0 0 4px rgba(49,217,168,.16);animation:pulse 2.6s ease-in-out infinite}
@keyframes pulse{50%{opacity:.45}}
.hero h1{
  font-size:clamp(2.1rem,5.4vw,3.9rem);line-height:1.12;letter-spacing:-.035em;margin-bottom:var(--sp3);
  background:linear-gradient(180deg,var(--fg) 30%,var(--fg-fade));
  -webkit-background-clip:text;background-clip:text;color:transparent;
}
.hero h1 em{font-style:normal;background:linear-gradient(96deg,var(--brand),var(--brand-2) 60%,var(--brand-3));
  -webkit-background-clip:text;background-clip:text;color:transparent}
.lede{font-size:clamp(1rem,1.35vw,1.14rem);color:var(--fg-2);max-width:44ch;margin-bottom:var(--sp4)}
.cta{display:flex;flex-wrap:wrap;gap:12px;margin-bottom:var(--sp4)}
.btn{
  display:inline-flex;align-items:center;gap:9px;font-weight:700;font-size:15px;
  padding:13px 22px;border-radius:12px;border:1px solid transparent;cursor:pointer;
  transition:translate .18s,box-shadow .2s,background .2s,border-color .2s;
}
.btn:hover{text-decoration:none;translate:0 -2px}
.btn:active{translate:0 0}
.btn-p{background:linear-gradient(120deg,var(--brand),#57E8C0);color:#04140E;box-shadow:0 14px 30px -16px rgba(49,217,168,.85)}
.btn-s{background:var(--surface-2);border-color:var(--border);color:var(--fg)}
.btn-s:hover{border-color:var(--brand)}
.stats{display:flex;flex-wrap:wrap;gap:clamp(18px,3vw,36px);list-style:none;padding:0;margin:0}
.stats b{display:block;font-size:1.5rem;font-weight:800;letter-spacing:-.02em;color:var(--brand)}
.stats span{font-size:12.5px;color:var(--fg-3);font-weight:600}
.term{
  background:linear-gradient(180deg,var(--surface-2),var(--surface));
  border:1px solid var(--border);border-radius:var(--r-lg);overflow:hidden;
  box-shadow:var(--shadow);font-size:13.5px;
}
.term-bar{display:flex;align-items:center;gap:7px;padding:11px 14px;border-bottom:1px solid var(--border-soft);background:var(--surface-3)}
.term-bar i{width:10px;height:10px;border-radius:50%;background:var(--border);display:block}
.term-bar i:nth-child(1){background:#F87171}.term-bar i:nth-child(2){background:#FBBF24}.term-bar i:nth-child(3){background:#34D399}
.term-bar span{margin-left:8px;font-family:var(--mono);font-size:11.5px;color:var(--fg-3);letter-spacing:.04em}
.term-body{margin:0;padding:16px;font-family:var(--mono);font-size:13px;line-height:1.85;color:var(--fg-2);white-space:pre-wrap;word-break:break-word;min-height:8em}
.term-body .p{color:var(--brand)}
.term-body .cm{color:var(--fg-3)}
.caret{display:inline-block;width:8px;height:1.05em;background:var(--brand);vertical-align:-.18em;margin-left:2px;animation:blink 1.05s steps(1) infinite}
@keyframes blink{50%{opacity:0}}

/* ---------- 5. 布局骨架 ---------- */
.page{max-width:var(--maxw);margin:0 auto;padding:clamp(28px,4vw,52px) clamp(14px,3vw,28px) var(--sp6);
  display:grid;grid-template-columns:268px minmax(0,1fr);gap:clamp(24px,3vw,48px);align-items:start}
.sidebar{position:sticky;top:84px;max-height:calc(100vh - 108px);overflow-y:auto;overscroll-behavior:contain;
  border:1px solid var(--border);background:var(--surface);border-radius:var(--r);padding:18px 14px;box-shadow:var(--shadow)}
.sidebar::-webkit-scrollbar{width:8px}
.sidebar::-webkit-scrollbar-thumb{background:var(--border);border-radius:8px}
.sb-head{display:flex;align-items:center;gap:8px;font-size:12px;font-weight:700;letter-spacing:.1em;color:var(--fg-3);text-transform:uppercase;margin:0 4px 12px}
.sb-group{margin-bottom:14px}
.sb-group>p{margin:0 0 6px;padding:0 10px;font-size:11.5px;font-weight:700;letter-spacing:.08em;color:var(--brand);text-transform:uppercase}
.sidebar a{display:block;font-size:13.5px;color:var(--fg-2);padding:6px 10px;border-radius:9px;border-left:2px solid transparent;transition:background .16s,color .16s,border-color .16s}
.sidebar a:hover{background:var(--surface-2);color:var(--fg);text-decoration:none}
.sidebar a.on{background:var(--surface-2);color:var(--fg);border-left-color:var(--brand);font-weight:600}
.sb-prog{margin:16px 4px 4px;padding-top:14px;border-top:1px solid var(--border-soft);font-size:12.5px;color:var(--fg-3)}
.bar{height:7px;border-radius:99px;background:var(--surface-3);overflow:hidden;margin-top:8px}
.bar i{display:block;height:100%;width:0;border-radius:99px;background:linear-gradient(90deg,var(--brand),var(--brand-2));transition:width .35s ease}
.content{min-width:0;max-width:82ch}

/* ---------- 6. 章节 ---------- */
.part{
  display:flex;align-items:center;gap:14px;margin:var(--sp6) 0 var(--sp3);
  font-size:12.5px;font-weight:800;letter-spacing:.14em;text-transform:uppercase;color:var(--brand)
}
.part:first-of-type{margin-top:0}
.part::after{content:"";flex:1;height:1px;background:linear-gradient(90deg,var(--border),transparent)}
.sec{scroll-margin-top:92px;padding-bottom:var(--sp5);border-bottom:1px solid var(--border-soft);margin-bottom:var(--sp5)}
.sec:last-of-type{border-bottom:0}
.sec-num{display:inline-flex;align-items:center;gap:8px;font-family:var(--mono);font-size:12px;font-weight:700;color:var(--brand);letter-spacing:.1em;margin-bottom:12px}
.sec-num::before{content:"";width:22px;height:1px;background:var(--brand);display:block}
.sec h2{font-size:clamp(1.45rem,2.6vw,2.05rem);letter-spacing:-.025em;margin-bottom:var(--sp2)}
.sec h3{font-size:1.13rem;margin:var(--sp4) 0 12px;display:flex;align-items:center;gap:9px}
.sec h3 .ic{color:var(--brand);font-size:1.05em}
.sec h4{font-size:1rem;margin:var(--sp3) 0 8px;color:var(--fg)}
.lead{font-size:1.06rem;color:var(--fg-2)}
.plain{background:var(--surface);border:1px solid var(--border);border-radius:var(--r);padding:clamp(16px,2.4vw,24px);margin:var(--sp3) 0}

/* 卡片 / 网格 */
.grid{display:grid;gap:16px}
.g2{grid-template-columns:repeat(2,minmax(0,1fr))}
.g3{grid-template-columns:repeat(3,minmax(0,1fr))}
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--r);padding:20px;transition:border-color .2s,translate .2s,box-shadow .2s}
.card:hover{border-color:color-mix(in srgb,var(--brand) 45%,var(--border));translate:0 -3px;box-shadow:var(--glow)}
.card h4{margin:0 0 8px;font-size:1rem;display:flex;align-items:center;gap:9px}
.card h4 .ic{color:var(--brand);font-size:1.15em}
.card p{margin:0;font-size:14.5px;color:var(--fg-2)}
.card ul{font-size:14.5px;color:var(--fg-2);margin-bottom:0}
.tile-ico{width:38px;height:38px;border-radius:11px;display:grid;place-items:center;background:var(--surface-3);color:var(--brand);font-size:19px;margin-bottom:12px}

/* 提示框 */
.callout{display:grid;grid-template-columns:auto 1fr;gap:13px;padding:16px 18px;border-radius:var(--r-sm);
  border:1px solid var(--border);border-left:3px solid var(--brand);background:var(--surface-2);margin:var(--sp3) 0;font-size:14.8px}
.callout .ic{font-size:19px;color:var(--brand);margin-top:3px}
.callout p:last-child{margin-bottom:0}
.callout h4{margin:0 0 6px;font-size:14.5px}
.callout.warn{border-left-color:var(--warn)}.callout.warn .ic{color:var(--warn)}
.callout.danger{border-left-color:var(--danger)}.callout.danger .ic{color:var(--danger)}
.callout.ok{border-left-color:var(--ok)}.callout.ok .ic{color:var(--ok)}

/* 代码块 */
.code{position:relative;margin:var(--sp3) 0;border:1px solid var(--border);border-radius:var(--r-sm);background:var(--bg-2);overflow:hidden}
.code-top{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:8px 12px;background:var(--surface-3);border-bottom:1px solid var(--border-soft)}
.code-top span{font-family:var(--mono);font-size:11.5px;color:var(--fg-3);letter-spacing:.05em}
.copy{display:inline-flex;align-items:center;gap:6px;background:transparent;border:1px solid var(--border);color:var(--fg-2);
  font-size:12px;font-weight:600;padding:6px 11px;min-height:32px;border-radius:8px;cursor:pointer;transition:color .18s,border-color .18s}
.copy:hover{color:var(--brand);border-color:var(--brand)}
.code pre{margin:0;padding:15px 16px;overflow-x:auto;font-size:13.2px;line-height:1.75;color:var(--fg-2)}
.code pre code{color:inherit;background:none;border:0;padding:0}
.kbd{display:inline-block;font-family:var(--mono);font-size:12px;background:var(--surface-3);border:1px solid var(--border);
  border-bottom-width:2px;border-radius:6px;padding:1px 7px;color:var(--fg);white-space:nowrap}

/* 步骤 */
.steps{counter-reset:s;list-style:none;padding:0;margin:var(--sp3) 0}
.steps>li{counter-increment:s;position:relative;padding:0 0 var(--sp3) 46px;border-left:1px solid var(--border);margin-left:14px}
.steps>li:last-child{border-left-color:transparent;padding-bottom:0}
.steps>li::before{content:counter(s);position:absolute;left:-14px;top:0;width:28px;height:28px;border-radius:50%;
  display:grid;place-items:center;background:var(--surface-3);border:1px solid var(--border);color:var(--brand);
  font:700 13px/1 var(--mono)}
.steps>li>strong{display:block;margin-bottom:4px;font-size:15px}
.steps>li>p{margin:0;font-size:14.6px;color:var(--fg-2)}
.steps>li>*:not(strong){font-size:14.6px;color:var(--fg-2)}

/* 表格 */
.tbl{width:100%;overflow-x:auto;margin:var(--sp3) 0;border:1px solid var(--border);border-radius:var(--r-sm);background:var(--surface)}
.tbl table{border-collapse:collapse;width:100%;font-size:14.4px;min-width:520px}
.tbl th,.tbl td{text-align:left;padding:11px 14px;border-bottom:1px solid var(--border-soft);vertical-align:top}
.tbl th{background:var(--surface-3);font-size:12.5px;font-weight:700;letter-spacing:.05em;color:var(--fg-2);text-transform:uppercase;position:sticky;top:0}
.tbl tr:last-child td{border-bottom:0}
.tbl td strong{color:var(--brand)}

/* 对比 好/坏 */
.cmp{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:var(--sp3) 0}
.cmp>div{border:1px solid var(--border);border-radius:var(--r-sm);padding:15px 16px;background:var(--surface)}
.cmp h4{margin:0 0 8px;font-size:14px;display:flex;align-items:center;gap:8px}
.cmp .bad{border-left:3px solid var(--danger)}.cmp .bad h4 .ic{color:var(--danger)}
.cmp .good{border-left:3px solid var(--ok)}.cmp .good h4 .ic{color:var(--ok)}
.cmp p,.cmp ul{margin:0;font-size:14.4px;color:var(--fg-2)}
.cmp code{font-size:.86em}

/* 折叠面板（原生 details，键盘可达） */
.acc{border:1px solid var(--border);border-radius:var(--r-sm);background:var(--surface);margin-bottom:10px;overflow:hidden}
.acc summary{cursor:pointer;padding:14px 16px;font-weight:600;font-size:15px;display:flex;align-items:center;gap:10px;list-style:none}
.acc summary::-webkit-details-marker{display:none}
.acc summary::after{content:"";width:9px;height:9px;margin-left:auto;border-right:2px solid var(--fg-3);border-bottom:2px solid var(--fg-3);
  transform:rotate(45deg);transition:transform .22s;flex:none}
.acc[open] summary::after{transform:rotate(-135deg)}
.acc summary:hover{background:var(--surface-2)}
.acc .acc-body{padding:0 16px 16px;font-size:14.6px;color:var(--fg-2);animation:fade .28s ease}
.acc .acc-body p:last-child,.acc .acc-body ul:last-child{margin-bottom:0}
@keyframes fade{from{opacity:0;translate:0 -4px}to{opacity:1;translate:0 0}}

/* 标签页 */
.tabs{margin:var(--sp3) 0}
.tablist{display:flex;gap:6px;flex-wrap:wrap;border-bottom:1px solid var(--border);margin-bottom:-1px;padding-bottom:0}
.tablist button{background:transparent;border:1px solid transparent;border-bottom:none;color:var(--fg-3);font:600 14px/1 var(--sans);
  padding:10px 14px;border-radius:10px 10px 0 0;cursor:pointer;transition:color .18s,background .18s}
.tablist button:hover{color:var(--fg);background:var(--surface-2)}
.tablist button[aria-selected=true]{color:var(--brand);background:var(--surface);border-color:var(--border);position:relative}
.tablist button[aria-selected=true]::after{content:"";position:absolute;inset:auto 0 -1px 0;height:1px;background:var(--surface)}
.tabpanel{border:1px solid var(--border);border-top:none;border-radius:0 0 var(--r-sm) var(--r-sm);padding:16px;background:var(--surface)}
.tabpanel[hidden]{display:none}

/* 徽标 */
.badge{display:inline-flex;align-items:center;gap:6px;font-size:12px;font-weight:700;padding:3px 10px;border-radius:999px;
  background:color-mix(in srgb,var(--brand) 16%,transparent);color:var(--brand);border:1px solid color-mix(in srgb,var(--brand) 35%,transparent)}
.badge.b2{background:color-mix(in srgb,var(--brand-2) 16%,transparent);color:var(--brand-2);border-color:color-mix(in srgb,var(--brand-2) 35%,transparent)}
.badge.b3{background:color-mix(in srgb,var(--warn) 16%,transparent);color:var(--warn);border-color:color-mix(in srgb,var(--warn) 35%,transparent)}

/* 术语 / 模板 / 筛选 */
.filter{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin:var(--sp3) 0}
.filter input{flex:1;min-width:200px;background:var(--surface);border:1px solid var(--border);color:var(--fg);
  padding:11px 14px;border-radius:var(--r-sm);font:400 15px/1.4 var(--sans)}
.filter input::placeholder{color:var(--fg-3)}
.chip{background:var(--surface-2);border:1px solid var(--border);color:var(--fg-2);font:600 13px/1 var(--sans);
  padding:8px 13px;border-radius:999px;cursor:pointer;transition:all .18s}
.chip:hover{color:var(--fg);border-color:var(--brand)}
.chip[aria-pressed=true]{background:color-mix(in srgb,var(--brand) 18%,transparent);color:var(--brand);border-color:var(--brand)}
.def{border-bottom:1px solid var(--border-soft);padding:14px 2px}
.def:last-child{border-bottom:0}
.def dt{font-weight:700;font-size:15.4px;color:var(--fg);display:flex;align-items:baseline;gap:8px;flex-wrap:wrap}
.def dt em{font-family:var(--mono);font-size:11.5px;font-style:normal;color:var(--fg-3);font-weight:500}
.def dd{margin:5px 0 0;font-size:14.6px;color:var(--fg-2)}
.def.hide{display:none}
.tmpl{background:var(--surface);border:1px solid var(--border);border-radius:var(--r-sm);padding:16px;display:flex;flex-direction:column;gap:10px}
.tmpl:hover{border-color:color-mix(in srgb,var(--brand) 45%,var(--border))}
.tmpl h4{margin:0;font-size:15px;display:flex;align-items:center;gap:8px}
.tmpl p{margin:0;font-size:14.2px;color:var(--fg-2);flex:1}
.tmpl pre{margin:0;background:var(--bg-2);border:1px solid var(--border-soft);border-radius:8px;padding:11px;font-size:12.6px;
  line-height:1.7;color:var(--fg-2);white-space:pre-wrap;word-break:break-word;max-height:11em;overflow:auto}
.tmpl.hide{display:none}

/* 学习打勾 */
.track{list-style:none;padding:0;margin:var(--sp3) 0}
.track li{display:flex;gap:12px;align-items:flex-start;border:1px solid var(--border);border-radius:var(--r-sm);
  background:var(--surface);padding:13px 15px;margin-bottom:9px;transition:border-color .2s}
.track li:hover{border-color:color-mix(in srgb,var(--brand) 40%,var(--border))}
.track input{margin-top:5px;width:18px;height:18px;accent-color:var(--brand);flex:none;cursor:pointer}
.track label{cursor:pointer;font-size:14.8px;color:var(--fg-2)}
.track input:checked+label{color:var(--fg-3);text-decoration:line-through}
.track b{display:block;color:var(--fg);font-size:15px;text-decoration:none}

/* 页脚 / 回到顶部 */
.foot{border-top:1px solid var(--border);background:var(--surface);padding:var(--sp5) clamp(14px,3vw,28px);margin-top:var(--sp4)}
.foot-in{max-width:var(--maxw);margin:0 auto;display:grid;grid-template-columns:1.4fr 1fr 1fr;gap:var(--sp4);font-size:14.4px;color:var(--fg-2)}
.foot h4{font-size:13px;letter-spacing:.1em;text-transform:uppercase;color:var(--fg-3);margin-bottom:12px}
.foot ul{list-style:none;padding:0;margin:0}
.foot a{color:var(--fg-2)}
.foot a:hover{color:var(--brand)}
.foot .fin{border-top:1px solid var(--border-soft);margin-top:var(--sp4);padding-top:18px;font-size:13px;color:var(--fg-3);
  max-width:var(--maxw);margin-left:auto;margin-right:auto}
.totop{position:fixed;right:20px;bottom:20px;z-index:45;opacity:0;pointer-events:none;transition:opacity .25s,translate .25s;translate:0 8px}
.totop.on{opacity:1;pointer-events:auto;translate:0 0}

/* 动效揭示（可降级：无 JS / 减少动效时内容始终可见） */
.reveal{opacity:1;transform:none}
html.js .reveal{opacity:0;transform:translate3d(0,14px,0);transition:opacity .45s cubic-bezier(.22,.7,.3,1),transform .45s cubic-bezier(.22,.7,.3,1)}
html.js .reveal.in{opacity:1;transform:none}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation-duration:.001ms!important;animation-iteration-count:1!important;transition-duration:.001ms!important}
  html.js .reveal{opacity:1;transform:none}
}

/* ---------- 7. 响应式 ---------- */
/* 触屏设备：所有可点元素至少 44px 高 */
@media (pointer:coarse){
  .iconbtn{width:44px;height:44px;border-radius:12px}
  .copy{min-height:44px;padding:10px 14px}
  .chip{min-height:44px;display:inline-flex;align-items:center}
  .tablist button{padding:13px 16px;min-height:44px}
  .sidebar a{min-height:44px;display:flex;align-items:center}
  .card:hover{translate:0 0}
}
@media (max-width:1080px){
  .hero-in{grid-template-columns:1fr;gap:var(--sp4)}
  .hero .term{order:2}
  .page{grid-template-columns:minmax(0,1fr)}
  #tocBtn{display:grid}
  .sidebar{position:fixed;z-index:70;top:0;left:0;height:100dvh;max-height:none;width:min(88vw,320px);
    border-radius:0;border:0;border-right:1px solid var(--border);translate:-102% 0;transition:translate .3s cubic-bezier(.3,.8,.3,1);padding:20px 16px calc(20px + env(safe-area-inset-bottom))}
  .sidebar.open{translate:0 0}
  .scrim{position:fixed;inset:0;z-index:65;background:rgba(3,6,12,.66);opacity:0;pointer-events:none;transition:opacity .3s;backdrop-filter:blur(2px)}
  .scrim.on{opacity:1;pointer-events:auto}
  .topnav a{display:none}
  .foot-in{grid-template-columns:1fr 1fr}
}
@media (max-width:720px){
  body{font-size:15.5px}
  .g2,.g3,.cmp,.foot-in{grid-template-columns:1fr}
  .topbar{gap:8px}
  .hero{padding-top:calc(64px + 40px)}
  .stats{gap:20px}
  .stats b{font-size:1.3rem}
  .aurora{filter:blur(42px);opacity:.5}
  .sec{padding-bottom:var(--sp4);margin-bottom:var(--sp4)}
  .code pre{font-size:12.4px}
  .totop{right:14px;bottom:14px}
}
@media print{
  .topbar,.sidebar,.totop,.progress,.hero .term,.copy{display:none!important}
  body{background:#fff;color:#000}
  .card,.plain,.acc,.tbl{border-color:#ccc}
}