:root{
  --ink:#0B2545;--deep:#1F4D78;--blue:#2E74B5;--soft:#E8EEF5;
  --orange:#F2A93B;--green:#2E7D32;--red:#C0392B;--gray:#6B7A8C;--bg:#F5F7FA;--line:#DCE3EB;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:"Microsoft YaHei","PingFang SC","Segoe UI",sans-serif;color:var(--ink);background:var(--bg);line-height:1.65}
a{color:inherit;text-decoration:none}
.wrap{max-width:1180px;margin:0 auto;padding:0 24px}

/* nav */
.nav{position:sticky;top:0;z-index:50;display:flex;align-items:center;gap:28px;padding:14px 28px;background:rgba(255,255,255,.94);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
.brand{display:flex;align-items:center;gap:10px;font-weight:700;font-size:20px}
.brand img{width:34px;height:34px;border-radius:9px}
.brand span{font-size:12px;font-weight:400;color:var(--gray);margin-top:5px}
.links{display:flex;gap:22px;margin-left:auto;color:#33475B;font-size:15px}
.links a:hover{color:var(--blue)}
.btn{display:inline-flex;align-items:center;justify-content:center;padding:11px 20px;border-radius:10px;font-weight:600;cursor:pointer;border:1px solid transparent;transition:.2s}
.btn-primary{background:var(--blue);color:#fff}
.btn-primary:hover{background:var(--deep)}
.btn-ghost{background:#fff;border-color:var(--line);color:var(--deep)}
.btn-nav{padding:8px 16px;font-size:14px}

/* hero */
.hero{background:radial-gradient(1200px 600px at 85% -10%,#2E74B5 0%,#0B2545 55%,#071A33 100%);color:#fff;padding:84px 0 90px}
.hero-grid{display:grid;grid-template-columns:1.05fr .95fr;gap:56px;align-items:center}
.eyebrow{color:#9FC3E8;font-size:14px;letter-spacing:.12em;margin-bottom:16px}
.hero h1{font-size:52px;line-height:1.18;font-weight:800}
.hero h1 em{font-style:normal;color:var(--orange)}
.hero .sub{color:#C9D9EC;font-size:17px;margin:20px 0 30px;max-width:520px}
.cta{display:flex;gap:14px;margin-bottom:38px}
.stats{display:flex;gap:42px}
.stats b{display:block;font-size:30px;color:#fff}
.stats span{font-size:13px;color:#9FC3E8}
.hero-card{background:#fff;border-radius:18px;box-shadow:0 24px 60px rgba(0,0,0,.28);padding:20px;color:var(--ink)}
.card-note{margin-top:12px;font-size:12px;color:var(--gray)}
.chat{display:flex;flex-direction:column;gap:10px;background:#F6F8FB;border-radius:14px;padding:16px}
.chat-head{display:flex;align-items:center;gap:8px;font-size:13px;color:var(--gray);border-bottom:1px solid var(--line);padding-bottom:10px}
.chat-head .dot{width:8px;height:8px;border-radius:50%;background:var(--green)}
.msg{max-width:88%;padding:10px 13px;border-radius:12px;font-size:14px;line-height:1.55}
.msg.ai{background:#fff;border:1px solid var(--line);align-self:flex-start}
.msg.user{background:var(--blue);color:#fff;align-self:flex-end}
.msg.check{border-left:3px solid var(--green)}
.badge.ok{display:inline-block;background:#E5F4E6;color:var(--green);font-size:12px;padding:1px 8px;border-radius:99px;margin-left:6px}
.badge.warn{display:inline-block;background:#FBF3E2;color:#B97A00;font-size:12px;padding:1px 8px;border-radius:99px;margin-left:6px}

/* sections */
.section{padding:88px 0}
.section.dark{background:var(--ink);color:#fff}
.section h2{font-size:34px;font-weight:800;margin-bottom:12px}
.section .lead{color:var(--gray);font-size:16px;margin-bottom:38px}
.dark .lead{color:#9FB3CC}
.grid.features{display:grid;grid-template-columns:repeat(4,1fr);gap:18px}
.card{background:#fff;border:1px solid var(--line);border-radius:16px;padding:24px;transition:.2s}
.card:hover{transform:translateY(-4px);box-shadow:0 16px 34px rgba(11,37,69,.10)}
.card .icon{display:flex;align-items:center;justify-content:center;width:46px;height:46px;border-radius:12px;background:var(--soft);color:var(--deep);font-size:21px;font-weight:800;margin-bottom:16px}
.card h3{font-size:18px;margin-bottom:8px}
.card p{font-size:14px;color:#4A5A6E}

/* demo */
.demo-layout{display:grid;grid-template-columns:180px 1fr;gap:18px;align-items:start}
.demo-side{display:flex;flex-direction:column;gap:10px}
.topic{background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.18);color:#C9D9EC;padding:12px;border-radius:12px;text-align:left;font-size:15px;cursor:pointer}
.topic small{color:#8FA8C4;font-size:12px}
.topic.active{background:var(--blue);border-color:var(--blue);color:#fff}
.topic.active small{color:#D9E8F7}
.demo-main{background:#F6F8FB;border-radius:16px;padding:20px;min-height:430px;display:flex;flex-direction:column}
.chat-big{flex:1}
.prompt-row{display:flex;gap:10px;margin-top:14px;flex-wrap:wrap}
.prompt-row button{background:#fff;border:1px solid var(--line);color:var(--deep);padding:9px 14px;border-radius:9px;font-size:14px;cursor:pointer}
.prompt-row button:hover{border-color:var(--blue);color:var(--blue)}
.meta-row{margin-top:12px;font-size:12px;color:var(--gray)}
.ask-row{display:flex;gap:10px;margin-top:12px}
.ask-row input{flex:1;background:#fff;border:1px solid var(--line);color:var(--ink);border-radius:10px;padding:11px 14px;font-size:14px}
.ask-row input::placeholder{color:#9AA8B8}
.ask-row .btn{white-space:nowrap}
.msg .typing{display:inline-block;animation:blink 1s steps(2) infinite}
@keyframes blink{50%{opacity:.35}}
.msg.ai .b{font-weight:700;color:#1F4D78}
.msg.ai code{background:#E8EEF5;border-radius:5px;padding:1px 5px;font-size:13px}

/* sandbox */
.sandbox-wrap{display:grid;grid-template-columns:1fr 1fr;gap:24px;align-items:start}
pre{background:var(--ink);color:#D8E4F2;padding:22px;border-radius:14px;font-size:13px;overflow:auto;margin:18px 0}
.output-panel{background:#fff;border:1px solid var(--line);border-radius:14px;min-height:220px}
.output-head{padding:10px 16px;border-bottom:1px solid var(--line);color:var(--gray);font-size:13px}
#output{padding:16px;font-size:14px;color:#33475B}

/* charts */
.chart-row{display:grid;grid-template-columns:1fr 1fr;gap:18px}
.chart-card{background:#fff;border:1px solid var(--line);border-radius:16px;padding:24px}
.chart-card h3{font-size:16px;margin-bottom:20px}
.bars{display:flex;align-items:flex-end;gap:20px;height:220px}
.bars>div{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:flex-end;height:100%}
.bars i{display:block;width:100%;max-width:70px;background:linear-gradient(180deg,#5B93C9,#2E74B5);border-radius:8px 8px 0 0}
.bars span{margin-top:8px;font-size:12px;color:var(--gray);text-align:center;line-height:1.4}
.bars.trio i.b1{background:#9FC3E8}.bars.trio i.b2{background:#5B93C9}.bars.trio i.b3{background:var(--orange)}

/* apply form */
.apply-wrap{display:grid;grid-template-columns:1fr 1fr;gap:48px;align-items:center}
.privacy{font-size:12px;color:#8FA8C4;margin-top:10px}
.form{display:grid;grid-template-columns:1fr 1fr;gap:14px;background:rgba(255,255,255,.05);border:1px solid rgba(255,255,255,.14);padding:24px;border-radius:16px}
.form label{display:flex;flex-direction:column;gap:6px;font-size:13px;color:#C9D9EC}
.form .full{grid-column:1/-1}
input,select,textarea{background:rgba(255,255,255,.08);border:1px solid rgba(255,255,255,.2);border-radius:9px;color:#fff;padding:11px 12px;font-size:14px;font-family:inherit}
input::placeholder,textarea::placeholder{color:#7E93AB}
select option{color:#1A2B44}
textarea{min-height:76px;resize:vertical}
#formMsg{grid-column:1/-1;font-size:13px;color:#8FD3A4}

/* footer */
.footer{background:#06182B;color:#8FA8C4;padding:30px 0;text-align:center;font-size:13px}
.footer img{width:30px;height:30px;border-radius:8px;margin-bottom:8px}

/* dashboard */
.dash-head{display:flex;justify-content:space-between;align-items:flex-end;padding-top:42px;padding-bottom:24px;flex-wrap:wrap;gap:18px}
.dash-head h1{font-size:30px}
.dash-head p{color:var(--gray);margin-top:6px}
.kpis{display:flex;gap:14px}
.kpi{background:#fff;border:1px solid var(--line);border-radius:12px;padding:14px 20px;text-align:center;min-width:110px}
.kpi b{display:block;font-size:24px;color:var(--deep)}
.kpi span{font-size:12px;color:var(--gray)}
.kpi.warn b{color:var(--red)}
.dash-grid{display:grid;grid-template-columns:1.2fr 1fr;gap:18px;padding-bottom:60px}
.panel{background:#fff;border:1px solid var(--line);border-radius:16px;padding:22px}
.panel h2{font-size:18px;margin-bottom:18px}
.bars.h{height:200px}
.bars.h span{font-size:11px}
.heat div{display:flex;align-items:center;gap:12px;margin-bottom:14px;font-size:13px}
.heat span{width:118px;color:#33475B}
.heat i{flex:1;height:10px;background:var(--soft);border-radius:99px;overflow:hidden}
.heat b{display:block;height:100%;background:linear-gradient(90deg,#5B93C9,#2E74B5);border-radius:99px}
.heat em{width:44px;color:var(--gray);font-style:normal;text-align:right}
.tbl{width:100%;border-collapse:collapse;font-size:13px}
.tbl th{background:var(--soft);color:var(--deep);padding:9px 10px;text-align:left}
.tbl td{padding:9px 10px;border-bottom:1px solid var(--line)}
.red{color:var(--red);font-weight:600}.amber{color:#B97A00;font-weight:600}.ok{color:var(--green)}
.qa div{display:flex;gap:10px;align-items:flex-start;padding:12px 0;border-bottom:1px solid var(--line);font-size:13px}
.qa b{color:var(--blue)}
.qa p{flex:1}
.qa span{color:var(--gray);font-size:12px;white-space:nowrap}
.user-chip{color:var(--gray);font-size:13px}

/* verify center */
.verify-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.verify-card{background:#fff;border:1px solid var(--line);border-radius:16px;padding:22px;border-left:5px solid var(--blue);box-shadow:0 8px 24px rgba(11,37,69,.05)}
.verify-card h3{font-size:17px;color:var(--deep);margin-bottom:14px;display:flex;align-items:center;gap:8px}
.verify-card h3::before{content:"";display:inline-block;width:9px;height:9px;border-radius:50%;background:var(--blue)}
.step{background:#F6F9FC;border:1px solid #E4EBF2;border-radius:9px;padding:9px 12px;font-size:13px;color:#33475B;margin-bottom:9px;display:flex;flex-wrap:wrap;gap:6px;align-items:center;justify-content:space-between}
.verify-card .note{font-size:12px;color:var(--gray);margin-top:6px;line-height:1.6}
.section.soft{background:#EFF3F8}

/* knowledge graph */
.graph-layout{display:grid;grid-template-columns:1.1fr .9fr;gap:22px;align-items:start}
.graph-panel{background:#fff;border:1px solid var(--line);border-radius:16px;padding:14px}
.kgraph{width:100%;height:auto;display:block}
.kgraph .node{cursor:pointer;transition:.2s}
.kgraph .node:hover circle{fill:#DCE9F7}
.kgraph .node.active circle{fill:#2E74B5}
.kgraph .node.active text{fill:#fff}
.graph-aside{display:flex;flex-direction:column;gap:14px}
.node-card,.radar-box,.wrongbook{background:#fff;border:1px solid var(--line);border-radius:14px;padding:18px}
.node-card h3,.radar-box h3,.wrongbook h3{font-size:15px;color:var(--deep);margin-bottom:10px}
.meter{height:10px;background:var(--soft);border-radius:99px;overflow:hidden;margin-bottom:10px}
.meter i{display:block;height:100%;background:linear-gradient(90deg,#5B93C9,#2E74B5)}
.node-card p{font-size:13px;color:#33475B}
.radar{width:100%;height:auto}
.wrongbook div{display:flex;align-items:center;gap:8px;padding:7px 0;border-bottom:1px solid var(--line);font-size:13px}
.wrongbook div:last-child{border-bottom:none}
.wrongbook span{flex:1}
.wrongbook em{color:var(--gray);font-style:normal}

/* quiz */
.quiz-layout{display:grid;grid-template-columns:1.1fr .9fr;gap:24px;align-items:start}
.quiz-card{background:#fff;border:1px solid var(--line);border-radius:16px;padding:24px;box-shadow:0 8px 24px rgba(11,37,69,.05)}
.quiz-head{display:flex;justify-content:space-between;align-items:center;margin-bottom:6px}
.quiz-head .tag{background:var(--soft);color:var(--deep);font-size:12px;padding:3px 10px;border-radius:99px}
.quiz-card .q{font-size:15px;font-weight:700;color:var(--ink);margin:14px 0 8px}
.quiz-card .q:first-child{margin-top:0}
.opt{display:flex;align-items:center;gap:10px;padding:10px 14px;border:1px solid var(--line);border-radius:10px;margin-bottom:7px;cursor:pointer;font-size:14px;color:#33475B;transition:.15s}
.opt:hover{border-color:var(--blue);background:#F7FAFD}
.opt:has(input:checked){border-color:var(--blue);background:var(--soft);color:var(--deep);font-weight:600}
.opt .letter{display:inline-flex;align-items:center;justify-content:center;width:24px;height:24px;border-radius:7px;background:var(--soft);color:var(--deep);font-size:12px;font-weight:700}
.opt input{accent-color:var(--blue)}
.quiz-result{margin-top:14px;font-size:14px;font-weight:700;color:var(--deep);background:#EAF4EC;border:1px solid #CFE6D2;border-radius:10px;padding:12px}
.photo-card{background:#fff;border:1px solid var(--line);border-radius:16px;padding:22px;margin-bottom:18px}
.photo-card h3{font-size:16px;color:var(--deep);margin-bottom:12px}
.photo-btn{cursor:pointer;width:100%}
.mock-output{background:#F6F8FB;border:1px solid var(--line);border-radius:10px;padding:12px;font-size:13px;color:#33475B;margin-top:12px;min-height:52px}

/* engineering */
.grid.eng{grid-template-columns:repeat(4,1fr)}
.mock-lines{display:flex;flex-direction:column;gap:6px;font-size:13px;color:#33475B}
.mock-lines span{background:#F6F8FB;border-radius:7px;padding:6px 9px}
.term{background:var(--ink);color:#D8E4F2;border-radius:10px;padding:12px;font-family:Consolas,monospace;font-size:12px;line-height:1.7}

@media(max-width:900px){
  .hero-grid,.demo-layout,.sandbox-wrap,.chart-row,.apply-wrap,.dash-grid{grid-template-columns:1fr}
  .grid.features,.grid.eng,.verify-grid,.graph-layout,.quiz-layout{grid-template-columns:1fr}
  .links{display:none}
  .hero h1{font-size:38px}
}