:root{--bg:#f6f7f9;--card:#fff;--ink:#141922;--muted:#5c6572;--line:#e3e7ee;
--accent:#1f5fd0;--accent-soft:#e8f0fe;--ok:#0f8a4d;--warn:#b45309;--bad:#b42318;
--radius:14px;--shadow:0 1px 2px rgba(16,24,40,.06),0 8px 24px rgba(16,24,40,.06)}
*{box-sizing:border-box}
body{margin:0;font:16px/1.65 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Inter,Helvetica,Arial,sans-serif;
background:var(--bg);color:var(--ink)}
.wrap{max-width:1180px;margin:0 auto;padding:0 20px}
.topbar{position:sticky;top:0;z-index:20;background:#0f1729;color:#fff;box-shadow:var(--shadow)}
.topbar-in{display:flex;align-items:center;gap:24px;height:60px;overflow-x:auto}
.brand{color:#fff;text-decoration:none;font-weight:700;letter-spacing:-.2px;white-space:nowrap;font-size:17px}
.brand-mark{display:inline-grid;place-items:center;width:24px;height:24px;border-radius:7px;
background:linear-gradient(135deg,#3b82f6,#22d3ee);margin-right:6px;font-weight:800}
.brand-dot{color:#38bdf8}
.nav{display:flex;gap:2px;margin-left:auto}
.nav-link{color:#c7d2e4;text-decoration:none;padding:7px 11px;border-radius:8px;font-size:14px;white-space:nowrap}
.nav-link:hover{background:#1c2740;color:#fff}
.nav-link.active{background:var(--accent);color:#fff}
.main{padding:32px 20px 64px}
h1{font-size:34px;line-height:1.2;letter-spacing:-.6px;margin:0 0 8px}
h2{font-size:23px;margin:34px 0 12px;letter-spacing:-.3px}
h3{font-size:18px;margin:24px 0 8px}
h4{font-size:15px;margin:18px 0 6px;text-transform:uppercase;letter-spacing:.6px;color:var(--muted)}
p{margin:0 0 12px}
a{color:var(--accent)}
code{font:13px/1.5 ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;background:#eef1f6;
padding:2px 6px;border-radius:6px}
pre{background:#0f1729;color:#e6ebf5;padding:16px;border-radius:var(--radius);overflow:auto;font-size:13px}
pre code{background:none;color:inherit;padding:0}
table{width:100%;border-collapse:collapse;background:var(--card);border-radius:var(--radius);
overflow:hidden;box-shadow:var(--shadow);font-size:14px;margin:0 0 18px}
th,td{padding:10px 12px;text-align:left;border-bottom:1px solid var(--line);vertical-align:top}
th{background:#f0f3f8;font-size:12px;text-transform:uppercase;letter-spacing:.5px;color:var(--muted)}
tr:last-child td{border-bottom:none}
tbody tr:hover{background:#fafbfe}
blockquote{margin:0 0 16px;padding:12px 16px;border-left:4px solid var(--accent);
background:var(--accent-soft);border-radius:0 10px 10px 0}
hr{border:none;border-top:1px solid var(--line);margin:28px 0}
ul,ol{margin:0 0 14px;padding-left:22px}
li{margin:4px 0}
.card{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);padding:20px;margin:0 0 18px}
.grid{display:grid;gap:16px;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));margin:0 0 24px}
.kpi{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);padding:18px}
.kpi b{display:block;font-size:30px;letter-spacing:-.8px;line-height:1.1}
.kpi span{color:var(--muted);font-size:13px}
.hero{background:linear-gradient(135deg,#0f1729,#1b2f5c);color:#fff;border-radius:18px;
padding:34px;margin:0 0 26px;box-shadow:var(--shadow)}
.hero h1{color:#fff}
.hero p{color:#c7d2e4;max-width:70ch;margin:0}
.hero .tag{display:inline-block;background:rgba(56,189,248,.18);color:#7dd3fc;border:1px solid rgba(125,211,252,.35);
padding:4px 10px;border-radius:999px;font-size:12px;letter-spacing:.4px;margin-bottom:14px}
.badge{display:inline-block;padding:2px 8px;border-radius:999px;font-size:11px;font-weight:600;
letter-spacing:.3px;text-transform:uppercase}
.b-pt{background:#e0f2fe;color:#075985}.b-en{background:#fef3c7;color:#92400e}.b-zh{background:#fce7f3;color:#9d174d}
.b-mcq{background:#dcfce7;color:#166534}.b-open{background:#ede9fe;color:#5b21b6}.b-calc{background:#ffedd5;color:#9a3412}
.toolbar{display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin:0 0 16px}
.toolbar input,.toolbar select{font:14px inherit;padding:9px 12px;border:1px solid var(--line);
border-radius:10px;background:var(--card);color:var(--ink);min-width:150px}
.toolbar input[type=search]{flex:1;min-width:240px}
.item{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);padding:16px 18px;margin:0 0 12px}
.item .q{margin:8px 0 10px;font-weight:600}
.item .opts{display:grid;gap:6px;margin:0 0 10px}
.opt{padding:7px 11px;border:1px solid var(--line);border-radius:9px;font-size:14px}
.opt.ok{border-color:var(--ok);background:#f0fdf4;font-weight:600}
.why{color:var(--muted);font-size:13.5px;border-top:1px dashed var(--line);padding-top:8px;margin-top:8px}
.rub{margin:8px 0 0;padding-left:20px;font-size:14px;color:#33404f}
.meta{display:flex;flex-wrap:wrap;gap:6px;align-items:center;font-size:12px;color:var(--muted)}
.pager{display:flex;gap:8px;align-items:center;justify-content:center;margin:18px 0}
.pager button{font:14px inherit;padding:8px 14px;border:1px solid var(--line);border-radius:10px;
background:var(--card);cursor:pointer}
.pager button:hover:not(:disabled){border-color:var(--accent);color:var(--accent)}
.pager button:disabled{opacity:.45;cursor:default}
.dl{display:flex;flex-wrap:wrap;gap:10px;margin:0 0 18px}
.dl a{display:inline-flex;align-items:center;gap:8px;text-decoration:none;font-size:14px;
padding:10px 14px;border:1px solid var(--line);border-radius:10px;background:var(--card);color:var(--ink)}
.dl a:hover{border-color:var(--accent);color:var(--accent)}
.muted{color:var(--muted)}
.note{background:#fffbeb;border:1px solid #fde68a;border-radius:12px;padding:14px 16px;margin:0 0 20px;font-size:14.5px}
.foot{border-top:1px solid var(--line);background:var(--card);padding:26px 0;font-size:13.5px;color:var(--muted)}
.foot strong{color:var(--ink)}
@media(max-width:820px){.nav{margin-left:0}.topbar-in{height:auto;padding:10px 20px;flex-wrap:wrap}
h1{font-size:27px}.hero{padding:24px}}