:root{--bg:#071018;--panel:#10202b;--ink:#eef8ff;--muted:#a8c3d3;--accent:#54d3ff;--gold:#f7c66a;--line:rgba(255,255,255,.14)}
*{box-sizing:border-box}body{margin:0;font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",Arial,sans-serif;background:linear-gradient(135deg,#071018,#10243a 50%,#182818);color:var(--ink);line-height:1.65}
a{color:inherit}.layout{display:grid;grid-template-columns:280px 1fr;min-height:100vh}.sidebar{position:sticky;top:0;height:100vh;overflow:auto;padding:24px 18px;background:rgba(5,12,18,.82);border-right:1px solid var(--line);backdrop-filter:blur(14px)}
main{padding:28px clamp(18px,4vw,52px) 80px}.brand{font-weight:900;color:var(--gold);font-size:14px;letter-spacing:.08em}.side-title{font-size:24px;line-height:1.2;margin:12px 0}.progress-shell{height:10px;border:1px solid var(--line);border-radius:999px;overflow:hidden;background:#050b10}.progress-bar{height:100%;width:0;background:linear-gradient(90deg,var(--accent),var(--gold))}
.navlink{display:block;text-decoration:none;padding:10px 12px;margin:8px 0;border:1px solid var(--line);border-radius:8px;background:rgba(255,255,255,.04);font-size:14px;color:#d8edf7}.navlink:hover{border-color:var(--accent)}
.hero{border:1px solid var(--line);border-radius:8px;padding:32px;background:radial-gradient(circle at 20% 10%,rgba(84,211,255,.22),transparent 34%),linear-gradient(135deg,rgba(255,255,255,.08),rgba(255,255,255,.03));box-shadow:0 24px 80px rgba(0,0,0,.25)}
.shared-solution-resource{display:grid;grid-template-columns:58px minmax(0,1fr) auto;gap:16px;align-items:center;margin-top:22px;padding:18px;border:1px solid rgba(247,198,106,.45);border-left:5px solid var(--gold);border-radius:8px;background:rgba(247,198,106,.09)}.shared-solution-type{display:grid;place-items:center;width:52px;height:52px;border-radius:8px;background:var(--gold);color:#071018;font-size:13px;font-weight:900;letter-spacing:.08em}.shared-solution-resource strong{display:block;color:#fff;font-size:19px}.shared-solution-resource p{margin:5px 0 0;color:var(--muted)}.shared-solution-resource a{display:inline-flex;justify-content:center;border-radius:8px;padding:10px 14px;background:linear-gradient(135deg,var(--accent),var(--gold));color:#051018;text-decoration:none;font-weight:900;white-space:nowrap}
.kicker{color:var(--gold);font-weight:800}.hero h1{font-size:clamp(30px,5vw,58px);line-height:1.08;margin:10px 0 16px}.hero p{max-width:980px;color:#d7e9f2;font-size:18px}.facts{display:flex;flex-wrap:wrap;gap:10px;margin-top:20px}.pill{border:1px solid var(--line);background:rgba(255,255,255,.06);border-radius:999px;padding:8px 12px;color:#dff6ff}
.identity,.section,.lesson{border:1px solid var(--line);border-radius:8px;background:rgba(10,24,34,.78);padding:24px;margin-top:22px}.section h2,.lesson h2{margin-top:0;font-size:28px}.grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.card{border:1px solid var(--line);border-radius:8px;background:rgba(255,255,255,.05);padding:16px}.card strong{color:var(--gold)}
.lesson{scroll-margin-top:20px}.lesson-head{display:flex;align-items:flex-start;justify-content:space-between;gap:16px}.lesson-num{min-width:64px;height:48px;border-radius:8px;background:linear-gradient(135deg,var(--accent),var(--gold));color:#061018;font-weight:900;display:grid;place-items:center;font-size:16px}.lesson-title{flex:1}.lesson-title h2{margin:0}.output{color:var(--gold);font-weight:800}
.steps{counter-reset:item;display:grid;gap:10px}.step{position:relative;border:1px solid var(--line);border-radius:8px;background:rgba(255,255,255,.045);padding:14px 14px 14px 52px}.step:before{counter-increment:item;content:counter(item);position:absolute;left:14px;top:14px;width:26px;height:26px;border-radius:8px;background:var(--gold);color:#111;font-weight:900;text-align:center;line-height:26px}
.prompt{position:relative;background:#06121a;border:1px solid rgba(84,211,255,.35);border-radius:8px;padding:18px;white-space:pre-wrap;overflow:auto;color:#e8fbff}.copy{border:0;background:var(--accent);color:#05202a;font-weight:900;border-radius:8px;padding:9px 12px;cursor:pointer}
.practice{display:grid;grid-template-columns:1fr 1fr;gap:14px}.field label{display:block;color:var(--gold);font-weight:800;margin-bottom:6px}.field textarea,.field input,.field select{width:100%;min-height:92px;border-radius:8px;border:1px solid var(--line);background:rgba(255,255,255,.08);color:var(--ink);padding:12px;font:inherit}.field input,.field select{min-height:44px}.answer{display:none;margin-top:12px;border-left:4px solid var(--gold);padding:12px 14px;background:rgba(247,198,106,.1);border-radius:8px}.answer.open{display:block}.confirm{display:flex;gap:10px;align-items:flex-start;margin-top:16px;font-weight:800;color:#eafcff}.confirm input{margin-top:6px;transform:scale(1.2)}
.toolbar{display:flex;gap:10px;flex-wrap:wrap;margin-top:18px}.btn{border:1px solid var(--line);background:rgba(255,255,255,.08);color:var(--ink);border-radius:8px;padding:10px 14px;text-decoration:none;cursor:pointer}.btn.primary{background:linear-gradient(135deg,var(--accent),var(--gold));color:#051018;border:0;font-weight:900}
.hub-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:16px}.hub-card{display:block;text-decoration:none;border:1px solid var(--line);border-radius:8px;padding:18px;background:rgba(255,255,255,.06)}.hub-card h3{margin:0 0 8px;color:var(--gold)}
.hub-shell{max-width:1180px;margin:0 auto}.hub-controls{display:grid;grid-template-columns:1fr;gap:16px;margin-top:22px}.filter-panel{border:1px solid var(--line);border-radius:8px;background:rgba(10,24,34,.78);padding:18px}.filter-panel h2{font-size:18px;margin:0 0 12px;color:var(--gold)}.filter-row{display:flex;flex-wrap:wrap;gap:10px}.filter-btn{border:1px solid var(--line);border-radius:8px;background:rgba(255,255,255,.06);color:var(--ink);cursor:pointer;font:inherit;font-weight:800;padding:9px 13px}.filter-btn.active{background:linear-gradient(135deg,var(--accent),var(--gold));border-color:transparent;color:#051018}.hub-count{color:#d7e9f2;margin:16px 0 0}.subject-section{border:1px solid var(--line);border-radius:8px;background:rgba(10,24,34,.78);padding:22px;margin-top:18px}.subject-head{display:flex;justify-content:space-between;align-items:flex-start;gap:16px;margin-bottom:14px}.subject-head h2{margin:0;color:var(--gold);font-size:28px}.subject-head p{margin:4px 0 0;color:var(--muted)}.stage-row{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.stage-card{display:block;text-decoration:none;border:1px solid var(--line);border-radius:8px;padding:16px;background:rgba(255,255,255,.055)}.stage-card:hover{border-color:var(--accent);background:rgba(84,211,255,.08)}.stage-chip{display:inline-flex;border:1px solid rgba(247,198,106,.36);border-radius:8px;color:var(--gold);padding:2px 8px;font-size:13px;font-weight:900}.stage-card h3{margin:10px 0 8px;font-size:20px;line-height:1.3}.stage-card p{margin:0;color:#d8edf7}.stage-card .meta{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px;color:var(--muted);font-size:13px}.no-results{display:none;border:1px solid var(--line);border-radius:8px;padding:22px;margin-top:18px;background:rgba(10,24,34,.78);color:var(--muted)}
@media(max-width:860px){.layout{display:block}.sidebar{position:relative;height:auto}.grid,.practice,.stage-row{grid-template-columns:1fr}.lesson-head{display:block}.lesson-num{margin-bottom:12px}.subject-head{display:block}.shared-solution-resource{grid-template-columns:52px minmax(0,1fr)}.shared-solution-resource a{grid-column:1/-1}}
@media print{.sidebar,.toolbar,.copy{display:none}body{background:white;color:#111}.layout{display:block}.hero,.identity,.section,.lesson,.card,.step{background:white;color:#111;border-color:#bbb;box-shadow:none}.prompt{white-space:pre-wrap;color:#111;background:#f7f7f7}}