/* StarLearn · 学习资源页共用样式 (Resources shared stylesheet) */
:root{
  --red:#C0392B;--red-l:#E8524A;--red-bg:#FDF1F0;--red-d:#8E241A;
  --gold:#D4A017;--gold-l:#F0C24B;
  --ink:#171523;--ink-2:#4A4459;--ink-3:#7C7489;
  --paper:#FCFAF6;--paper-2:#F4EFE6;--paper-3:#E9E0D2;
  --green:#1E874B;--green-bg:#E9F6EE;
  --blue:#2563EB;--blue-bg:#EFF6FF;
  --purple:#7C3AED;
  --border:rgba(23,21,35,0.11);
  --shadow:0 4px 20px rgba(23,21,35,0.07);
  --shadow-lg:0 18px 46px rgba(23,21,35,0.14);
  --font-display:'Noto Serif SC',serif;
  --font-body:'Noto Sans SC',sans-serif;
  --maxw:1160px;
}
*{box-sizing:border-box;margin:0;padding:0;}
html{scroll-behavior:smooth;scroll-padding-top:78px;}
body{font-family:var(--font-body);background:var(--paper);color:var(--ink);line-height:1.75;-webkit-font-smoothing:antialiased;}
a{color:inherit;text-decoration:none;}
img{max-width:100%;display:block;}
:focus-visible{outline:3px solid var(--gold);outline-offset:2px;border-radius:6px;}
body:not(.lang-en) .lang-en{display:none!important;}
body.lang-en .lang-zh{display:none!important;}
html.preload-en .lang-zh{display:none!important;}
html.preload-en .lang-en{display:inline;}
@media (prefers-reduced-motion:reduce){ html{scroll-behavior:auto;} }

/* ── NAV ── */
.nav{position:sticky;top:0;background:rgba(252,250,246,0.9);backdrop-filter:blur(14px);-webkit-backdrop-filter:blur(14px);border-bottom:1px solid var(--border);z-index:100;}
.nav-inner{max-width:var(--maxw);margin:0 auto;padding:12px 24px;display:flex;align-items:center;gap:16px;}
.nav-logo{font-family:var(--font-display);font-size:18px;font-weight:700;display:flex;align-items:center;gap:9px;flex-shrink:0;}
.nav-logo img{width:30px;height:30px;border-radius:7px;}
.nav-links{display:flex;align-items:center;gap:2px;margin-left:6px;flex:1;}
.nav-links a{padding:8px 12px;border-radius:8px;font-size:14px;font-weight:500;color:var(--ink-2);white-space:nowrap;}
.nav-links a:hover{color:var(--red);background:var(--red-bg);}
.nav-links a.on{color:var(--red);font-weight:700;}
.nav-right{display:flex;gap:8px;align-items:center;flex-shrink:0;}
.lang-toggle{padding:7px 12px;background:transparent;border:1.5px solid var(--border);border-radius:8px;font-weight:700;font-size:12.5px;cursor:pointer;color:var(--ink-2);font-family:var(--font-body);display:inline-flex;gap:5px;align-items:center;}
.lang-toggle:hover{border-color:var(--red);color:var(--red);}
.nav-cta{padding:10px 18px;background:var(--red);color:#fff;border-radius:9px;font-weight:700;font-size:13.5px;white-space:nowrap;transition:background .15s,box-shadow .15s;}
.nav-cta:hover{background:var(--red-l);box-shadow:0 6px 18px rgba(192,57,43,.3);}

/* ── 页头 ── */
.res-hero{background:radial-gradient(120% 130% at 12% 0%,#2A2144 0%,#171523 52%,#0F0D18 100%);color:#fff;padding:52px 24px 56px;}
.res-hero-inner{max-width:840px;margin:0 auto;}
.crumb{font-size:12.5px;color:rgba(255,255,255,.5);margin-bottom:16px;}
.crumb a:hover{color:var(--gold-l);}
.crumb span{margin:0 7px;opacity:.5;}
.res-hero h1{font-family:var(--font-display);font-size:40px;font-weight:900;line-height:1.24;margin-bottom:14px;text-wrap:balance;}
.res-hero p{font-size:16px;color:rgba(255,255,255,.76);line-height:1.8;max-width:660px;}
.hero-meta{margin-top:20px;display:flex;gap:10px 20px;flex-wrap:wrap;font-size:12.5px;color:rgba(255,255,255,.55);}
.hero-meta span{display:inline-flex;align-items:center;gap:6px;}

/* ── 正文布局 ── */
.wrap{max-width:var(--maxw);margin:0 auto;padding:46px 24px 70px;display:grid;grid-template-columns:220px minmax(0,1fr);gap:44px;align-items:start;}
.doc{min-width:0;}
.wrap.single{grid-template-columns:minmax(0,1fr);max-width:900px;}
.toc{position:sticky;top:94px;font-size:13.5px;}
.toc h4{font-size:11.5px;font-weight:700;letter-spacing:.1em;text-transform:uppercase;color:var(--ink-3);margin-bottom:12px;}
.toc ul{list-style:none;border-left:2px solid var(--border);}
.toc li a{display:block;padding:7px 0 7px 14px;margin-left:-2px;border-left:2px solid transparent;color:var(--ink-2);line-height:1.5;}
.toc li a:hover{color:var(--red);border-left-color:var(--red);}
.doc h2{font-family:var(--font-display);font-size:26px;font-weight:800;margin:44px 0 14px;line-height:1.35;scroll-margin-top:90px;}
.doc h2:first-child{margin-top:0;}
.doc h3{font-family:var(--font-display);font-size:19px;font-weight:800;margin:28px 0 10px;}
.doc p{font-size:15.5px;color:var(--ink-2);margin-bottom:14px;line-height:1.85;}
.doc ul,.doc ol{margin:0 0 16px 20px;font-size:15px;color:var(--ink-2);}
.doc li{margin-bottom:7px;line-height:1.8;}
.doc strong{color:var(--ink);}
.doc a.inline{color:var(--red);text-decoration:underline;text-underline-offset:2px;}
.lead{font-size:16.5px;color:var(--ink-2);line-height:1.85;padding-bottom:6px;}

/* ── 表格 ── */
.tbl-wrap{overflow-x:auto;margin-bottom:20px;border:1px solid var(--border);border-radius:14px;background:#fff;box-shadow:var(--shadow);}
table{width:100%;border-collapse:collapse;min-width:520px;}
th,td{padding:12px 15px;text-align:left;border-bottom:1px solid var(--border);font-size:14px;vertical-align:top;line-height:1.65;}
th{background:var(--paper-2);font-weight:700;font-size:12.5px;letter-spacing:.03em;white-space:nowrap;}
tr:last-child td{border-bottom:none;}
td.num{font-variant-numeric:tabular-nums;white-space:nowrap;font-weight:700;}
tr.hi td{background:#FFFBEF;}

/* ── 提示框 ── */
.note{border-radius:14px;padding:16px 20px;font-size:14px;line-height:1.8;margin-bottom:20px;border:1px solid;}
.note.info{background:var(--blue-bg);border-color:#C7DAFB;color:#1E3A8A;}
.note.warn{background:#FFF8E4;border-color:#EBD79B;color:#7A5B00;}
.note.ok{background:var(--green-bg);border-color:#B7E2C8;color:#12603A;}
.note b{font-weight:700;}
.note a{text-decoration:underline;}

/* ── 年级 / 科目卡片 ── */
.grade-tabs{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:22px;}
.grade-tab{padding:8px 16px;border-radius:999px;border:1.5px solid var(--border);background:#fff;font-size:13.5px;font-weight:700;color:var(--ink-2);}
.grade-tab:hover{border-color:var(--red);color:var(--red);}
.topic-group{background:#fff;border:1px solid var(--border);border-radius:14px;padding:18px 20px;margin-bottom:14px;box-shadow:var(--shadow);}
.topic-group h4{font-family:var(--font-display);font-size:15.5px;font-weight:800;margin-bottom:12px;display:flex;align-items:center;gap:9px;}
.topic-group h4::before{content:'';width:5px;height:17px;border-radius:3px;background:var(--red);flex-shrink:0;}
.topic-group h4 small{font-weight:600;font-size:12px;color:var(--ink-3);}
.topics{display:flex;flex-wrap:wrap;gap:8px;}
.topics span{font-size:13px;background:var(--paper-2);border:1px solid var(--border);border-radius:9px;padding:7px 12px;color:var(--ink);line-height:1.45;}
.topics span i{font-style:normal;color:var(--ink-3);font-size:11.5px;display:block;}

/* ── 资源中心首页卡片 ── */
.res-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;}
.res-grid.two{grid-template-columns:repeat(2,1fr);}
.rcard{display:flex;flex-direction:column;background:#fff;border:1px solid var(--border);border-radius:16px;padding:24px 22px;box-shadow:var(--shadow);transition:transform .22s cubic-bezier(.22,.61,.36,1),box-shadow .22s,border-color .22s;height:100%;}
.rcard:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg);border-color:var(--red);}
.rcard .ic{font-size:28px;margin-bottom:12px;}
.rcard h3{font-family:var(--font-display);font-size:17.5px;font-weight:800;margin-bottom:8px;}
.rcard p{font-size:13.5px;color:var(--ink-2);line-height:1.72;margin-bottom:12px;}
.rcard ul{list-style:none;font-size:12.5px;color:var(--ink-3);line-height:1.95;margin-bottom:14px;}
.rcard .go{margin-top:auto;font-size:13px;font-weight:700;color:var(--red);}
.group-head{margin:52px 0 20px;}
.group-head:first-of-type{margin-top:0;}
.group-head h2{font-family:var(--font-display);font-size:25px;font-weight:800;margin-bottom:6px;}
.group-head p{font-size:14.5px;color:var(--ink-2);}

/* ── CTA 条 ── */
.cta-box{background:linear-gradient(135deg,var(--red-d) 0%,var(--red) 60%,var(--red-l) 100%);color:#fff;border-radius:18px;padding:30px 30px;margin:40px 0 10px;display:flex;align-items:center;justify-content:space-between;gap:22px;flex-wrap:wrap;}
.cta-box h3{font-family:var(--font-display);font-size:21px;font-weight:800;margin-bottom:6px;}
.cta-box p{font-size:14px;color:rgba(255,255,255,.88);margin:0;}
.cta-btn{background:#fff;color:var(--red);padding:13px 26px;border-radius:11px;font-weight:700;font-size:15px;white-space:nowrap;transition:transform .16s,box-shadow .16s;}
.cta-btn:hover{transform:translateY(-2px);box-shadow:0 10px 26px rgba(0,0,0,.22);}

/* ── FOOTER ── */
footer{background:var(--ink);color:rgba(255,255,255,0.66);padding:40px 24px 22px;font-size:13px;}
.footer-inner{max-width:var(--maxw);margin:0 auto 22px;display:grid;grid-template-columns:1.8fr 1fr 1fr 1fr;gap:28px;}
.footer-col h4{color:#fff;font-size:13px;font-weight:700;margin-bottom:12px;}
.footer-col ul{list-style:none;}
.footer-col li{padding:4px 0;}
.footer-col a:hover{color:#fff;}
.footer-bottom{border-top:1px solid rgba(255,255,255,0.1);padding-top:16px;text-align:center;font-size:12px;color:rgba(255,255,255,0.46);line-height:1.8;}

@media(max-width:540px){
  .nav-inner{padding:10px 14px;gap:10px;}
  .nav-logo{font-size:15px;min-width:0;flex-shrink:1;overflow:hidden;white-space:nowrap;}
  .nav-logo img{width:26px;height:26px;}
  .nav-cta{padding:9px 13px;font-size:12.5px;}
  .lang-toggle{padding:6px 9px;}
}
@media(max-width:900px){
  .wrap{grid-template-columns:minmax(0,1fr);gap:26px;padding:32px 18px 56px;}
  .toc{position:static;background:#fff;border:1px solid var(--border);border-radius:14px;padding:16px 18px;}
  .toc ul{display:flex;flex-wrap:wrap;gap:4px 6px;border-left:none;}
  .toc li a{padding:6px 11px;border:1px solid var(--border);border-radius:999px;margin-left:0;background:var(--paper-2);font-size:12.5px;}
  .res-hero{padding:38px 20px 42px;}
  .res-hero h1{font-size:28px;}
  .nav-links{display:none;}
  .res-grid,.res-grid.two{grid-template-columns:1fr;}
  .footer-inner{grid-template-columns:1fr 1fr;}
  .doc h2{font-size:22px;}
  .cta-box{padding:24px 22px;}
}