:root{--accent:#2f6fed;--font:-apple-system , BlinkMacSystemFont , "SF Pro Text" , "Segoe UI Variable" , "Segoe UI" , Inter , Roboto , "Helvetica Neue" , Arial , sans-serif;--mono:"SF Mono" , ui-monospace , "Cascadia Code" , Consolas , monospace;--bg:#eef1f6;--bg-wash-a:#dfe7f3;--bg-wash-b:#eae6f2;--ink:#1c1f26;--ink-2:#4a5160;--ink-3:#7a8194;--panel:rgba(255,255,255,.62);--panel-strong:rgba(255,255,255,.88);--panel-opaque:#fff;--line:rgba(20,30,60,.12);--line-soft:rgba(20,30,60,.07);--shadow:0 1px 2px rgba(16,24,40,.05) , 0 8px 24px rgba(16,24,40,.08);--shadow-lift:0 2px 6px rgba(16,24,40,.08) , 0 16px 40px rgba(16,24,40,.14);--ok:#1f9d55;--warn:#b7791f;--bad:#d64545;--radius:16px;--radius-sm:10px;--blur:saturate(180%) blur(18px)}html[data-theme="dark"],html[data-theme="auto"][data-osdark="1"]{color-scheme:dark}@media (prefers-color-scheme:dark){html[data-theme="auto"]{--bg:#14161b;--bg-wash-a:#1a2233;--bg-wash-b:#231d31;--ink:#eceef2;--ink-2:#b3b9c6;--ink-3:#7e8494;--panel:rgba(30,34,44,.58);--panel-strong:rgba(30,34,44,.86);--panel-opaque:#1e222c;--line:rgba(255,255,255,.13);--line-soft:rgba(255,255,255,.07);--shadow:0 1px 2px rgba(0,0,0,.4) , 0 8px 24px rgba(0,0,0,.5);--shadow-lift:0 2px 6px rgba(0,0,0,.5) , 0 16px 40px rgba(0,0,0,.6)}}html[data-theme="dark"]{--bg:#14161b;--bg-wash-a:#1a2233;--bg-wash-b:#231d31;--ink:#eceef2;--ink-2:#b3b9c6;--ink-3:#7e8494;--panel:rgba(30,34,44,.58);--panel-strong:rgba(30,34,44,.86);--panel-opaque:#1e222c;--line:rgba(255,255,255,.13);--line-soft:rgba(255,255,255,.07);--shadow:0 1px 2px rgba(0,0,0,.4) , 0 8px 24px rgba(0,0,0,.5);--shadow-lift:0 2px 6px rgba(0,0,0,.5) , 0 16px 40px rgba(0,0,0,.6)}html[data-theme="contrast"]{--bg:#fff;--bg-wash-a:#fff;--bg-wash-b:#fff;--ink:#000;--ink-2:#1a1a1a;--ink-3:#333;--panel:#fff;--panel-strong:#fff;--panel-opaque:#fff;--line:#000;--line-soft:#555;--shadow:none;--shadow-lift:none;--blur:none;--accent:#00c}html[data-reduced-glass="1"]{--panel:var(--panel-opaque);--panel-strong:var(--panel-opaque);--blur:none}@media (prefers-reduced-transparency:reduce){:root{--panel:var(--panel-opaque);--panel-strong:var(--panel-opaque);--blur:none}}*{box-sizing:border-box}html{-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}body{margin:0;font-family: var(--font);color:var(--ink);background:var(--bg);font-size:15.5px;line-height:1.55;min-height:100vh}.bg-wash{position:fixed;inset:0;z-index:-1;pointer-events:none;background:radial-gradient(60vw 40vh at 12% -5%,var(--bg-wash-a),transparent 60%) , radial-gradient(55vw 45vh at 95% 10%,var(--bg-wash-b),transparent 60%) , var(--bg)}h1,h2,h3,h4{line-height:1.25;letter-spacing:-.015em;margin:0 0 .5em}h1{font-size:1.7rem;font-weight:700}h2{font-size:1.25rem;font-weight:650}h3{font-size:1.05rem;font-weight:600}p{margin:0 0 1em}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}.skip-link{position:absolute;left:-9999px;top:0;background:var(--panel-opaque);padding:10px 16px;z-index:999;border-radius:0 0 8px 0}.skip-link:focus{left:0}:focus-visible{outline:3px solid var(--accent);outline-offset:2px;border-radius:4px}.glass{background:var(--panel);-webkit-backdrop-filter:var(--blur);backdrop-filter:var(--blur);border:1px solid var(--line-soft);box-shadow:var(--shadow)}.card{background:var(--panel);-webkit-backdrop-filter:var(--blur);backdrop-filter:var(--blur);border:1px solid var(--line-soft);border-radius:var(--radius);box-shadow:var(--shadow);padding:20px 22px;margin-bottom:18px}.card-opaque{background:var(--panel-opaque);-webkit-backdrop-filter:none;backdrop-filter:none}.card h2:first-child{margin-top:0}.topbar{position:sticky;top:0;z-index:50;border-left:0;border-right:0;border-top:0}.topbar-inner{max-width:1180px;margin:0 auto;display:flex;align-items:center;gap:18px;padding:10px 20px}.brand{display:flex;align-items:center;gap:10px;color:var(--ink)}.brand:hover{text-decoration:none}.brand-mark{width:26px;height:26px;border-radius:8px;background:linear-gradient(135deg,var(--accent),#7aa5f8);box-shadow:inset 0 0 0 1px rgba(255,255,255,.35) , 0 2px 6px rgba(47,111,237,.4)}.brand-sub{color:var(--ink-3);font-size:.85em;margin-left:4px}.mainnav{display:flex;gap:4px;flex-wrap:wrap;margin-left:8px}.mainnav a{padding:7px 12px;border-radius:9px;color:var(--ink-2);font-weight:500;font-size:.93rem}.mainnav a:hover{background:var(--line-soft);text-decoration:none;color:var(--ink)}.mainnav a[aria-current="page"]{background:var(--accent);color:#fff}.topbar-right{margin-left:auto;display:flex;align-items:center;gap:10px}.userchip{color:var(--ink-2);font-weight:550}.inline{display:inline}.container{max-width:1180px;margin:26px auto 60px;padding:0 20px}.site-footer{max-width:1180px;margin:0 auto 30px;padding:0 20px;color:var(--ink-3);font-size:.82rem}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;font:inherit;font-weight:600;font-size:.95rem;padding:10px 18px;border-radius:12px;border:1px solid var(--line);background:var(--panel-strong);color:var(--ink);cursor:pointer;transition:transform .06s ease , box-shadow .15s ease , background .15s ease}.btn:hover{text-decoration:none;box-shadow:var(--shadow)}.btn:active{transform:translateY(1px)}.btn-primary{background:var(--accent);border-color:transparent;color:#fff;box-shadow:0 2px 8px rgba(47,111,237,.35)}.btn-primary:hover{filter:brightness(1.06)}.btn-ghost{background:transparent;border-color:transparent;color:var(--ink-2)}.btn-ghost:hover{background:var(--line-soft)}.btn-danger{background:var(--bad);border-color:transparent;color:#fff}.btn-sm{padding:6px 12px;font-size:.87rem;border-radius:9px}.btn-lg{padding:13px 26px;font-size:1.05rem}.btn[disabled]{opacity:.5;cursor:not-allowed}label{display:block;font-weight:600;font-size:.9rem;margin:14px 0 6px}input[type="text"],input[type="email"],input[type="password"],input[type="date"],input[type="number"],select,textarea{font:inherit;width:100%;padding:10px 12px;border-radius:10px;border:1px solid var(--line);background:var(--panel-opaque);color:var(--ink)}textarea{min-height:90px;resize:vertical}.field-row{display:flex;gap:14px;flex-wrap:wrap}.field-row>div{flex:1;min-width:180px}.help{color:var(--ink-3);font-size:.84rem;margin-top:4px}.checkline{display:flex;align-items:center;gap:8px;font-weight:500;margin:8px 0}.checkline input{width:auto}.alert{padding:12px 16px;border-radius:12px;margin-bottom:16px;border:1px solid;font-weight:500}.alert-error{background:rgba(214,69,69,.08);border-color:rgba(214,69,69,.4);color:var(--bad)}.alert-ok{background:rgba(31,157,85,.08);border-color:rgba(31,157,85,.4);color:var(--ok)}.alert-info{background:rgba(47,111,237,.07);border-color:rgba(47,111,237,.35);color:var(--accent)}table.data{width:100%;border-collapse:collapse;font-size:.92rem}table.data th{text-align:left;font-weight:650;color:var(--ink-2);padding:8px 10px;border-bottom:2px solid var(--line);white-space:nowrap}table.data td{padding:8px 10px;border-bottom:1px solid var(--line-soft);vertical-align:top}table.data tr:hover td{background:var(--line-soft)}.badge{display:inline-block;padding:2px 9px;border-radius:99px;font-size:.78rem;font-weight:650;border:1px solid var(--line);color:var(--ink-2)}.badge-ok{color:var(--ok);border-color:rgba(31,157,85,.5);background:rgba(31,157,85,.07)}.badge-warn{color:var(--warn);border-color:rgba(183,121,31,.5);background:rgba(183,121,31,.07)}.badge-bad{color:var(--bad);border-color:rgba(214,69,69,.5);background:rgba(214,69,69,.07)}.badge-accent{color:var(--accent);border-color:rgba(47,111,237,.4);background:rgba(47,111,237,.07)}.grid{display:grid;gap:18px}.grid-3{grid-template-columns:repeat(auto-fit,minmax(230px,1fr))}.grid-2{grid-template-columns:repeat(auto-fit,minmax(320px,1fr))}.stat{padding:16px 18px}.stat .stat-label{color:var(--ink-3);font-size:.82rem;font-weight:600;text-transform:uppercase;letter-spacing:.04em}.stat .stat-value{font-size:1.9rem;font-weight:700;letter-spacing:-.02em;margin-top:2px}.stat .stat-sub{color:var(--ink-2);font-size:.85rem}.progressbar{height:8px;border-radius:99px;background:var(--line-soft);overflow:hidden}.progressbar>span{display:block;height:100%;border-radius:99px;background:linear-gradient(90deg,var(--accent),#7aa5f8)}.tasklist{list-style:none;margin:0;padding:0}.tasklist li{display:flex;align-items:center;gap:10px;padding:9px 0;border-bottom:1px solid var(--line-soft)}.tasklist li:last-child{border-bottom:0}.chart-svg{width:100%;height:auto;display:block}.legend{display:flex;gap:14px;flex-wrap:wrap;color:var(--ink-3);font-size:.8rem}.exam-body{background:var(--bg)}.exam-main{max-width:1240px;margin:0 auto;padding:14px 18px 30px}.exam-top{position:sticky;top:0;z-index:40;display:flex;align-items:center;gap:16px;background:var(--panel-opaque);border:1px solid var(--line-soft);border-radius:12px;padding:9px 16px;box-shadow:var(--shadow);margin-bottom:14px}.exam-title{font-weight:700}.exam-progress{color:var(--ink-2);font-size:.92rem}.exam-timer{margin-left:auto;font-family: var(--mono);font-size:1.15rem;font-weight:700;padding:5px 14px;border-radius:9px;background:var(--line-soft);min-width:92px;text-align:center}.exam-timer.warn{background:#ffd21f;color:#4a3b00}.exam-timer.untimed{font-size:.85rem;font-weight:600}.exam-layout{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:16px;align-items:start}.exam-layout.single{grid-template-columns:minmax(0,1fr);max-width:860px;margin:0 auto}.stimulus-panel,.question-panel{background:var(--panel-opaque);border:1px solid var(--line-soft);border-radius:12px;padding:20px 24px;box-shadow:var(--shadow)}.stimulus-panel{max-height:74vh;overflow:auto;font-size:1rem;line-height:1.65}.stimulus-panel h3{color:var(--ink-2)}.stimulus-panel table{border-collapse:collapse;width:100%;margin:10px 0;font-size:.95rem}.stimulus-panel table th,.stimulus-panel table td{border:1px solid var(--line);padding:6px 10px;text-align:right}.stimulus-panel table th:first-child,.stimulus-panel table td:first-child{text-align:left}.stimulus-panel table caption{caption-side:top;text-align:left;font-weight:650;padding-bottom:6px}.question-stem{font-size:1.04rem;font-weight:550;margin-bottom:16px}.options{list-style:none;margin:0;padding:0}.options li{margin-bottom:10px}.opt{display:flex;gap:12px;align-items:flex-start;width:100%;text-align:left;font:inherit;padding:12px 14px;border-radius:10px;border:1.5px solid var(--line);background:var(--panel-opaque);color:var(--ink);cursor:pointer}.opt:hover{border-color:var(--accent)}.opt[aria-pressed="true"]{border-color:var(--accent);background:rgba(47,111,237,.09);box-shadow:inset 0 0 0 1px var(--accent)}.opt .opt-letter{font-weight:700;color:var(--ink-3);min-width:1.2em}.opt[aria-pressed="true"] .opt-letter{color:var(--accent)}.ynrow{display:grid;grid-template-columns:1fr auto auto;gap:10px;align-items:center;padding:9px 0;border-bottom:1px solid var(--line-soft)}.ynrow .yn{padding:7px 18px;border-radius:9px;border:1.5px solid var(--line);background:var(--panel-opaque);font:inherit;font-weight:600;cursor:pointer}.ynrow .yn[aria-pressed="true"]{border-color:var(--accent);background:rgba(47,111,237,.1);color:var(--accent)}.rate-scale{display:grid;gap:8px}.exam-bottom{display:flex;align-items:center;gap:10px;margin-top:14px}.navigator{display:flex;flex-wrap:wrap;gap:6px;margin:12px 0}.navq{width:34px;height:34px;display:inline-flex;align-items:center;justify-content:center;border-radius:8px;border:1.5px solid var(--line);font:inherit;font-size:.82rem;font-weight:650;background:var(--panel-opaque);cursor:pointer;position:relative}.navq.answered{background:rgba(31,157,85,.14);border-color:rgba(31,157,85,.6)}.navq.flagged::after{content:"";position:absolute;top:-4px;right:-4px;width:10px;height:10px;border-radius:50%;background:var(--warn);border:1.5px solid var(--panel-opaque)}.navq.current{border-color:var(--accent);box-shadow:0 0 0 2px rgba(47,111,237,.35)}.flagbtn{border:1.5px solid var(--line);background:var(--panel-opaque);font:inherit;font-weight:600;padding:8px 14px;border-radius:9px;cursor:pointer}.flagbtn[aria-pressed="true"]{background:rgba(183,121,31,.12);border-color:var(--warn);color:var(--warn)}.calc{position:fixed;right:26px;top:90px;width:230px;z-index:60;background:var(--panel-opaque);border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow-lift);padding:12px}.calc-display{font-family: var(--mono);font-size:1.3rem;text-align:right;padding:8px 10px;background:var(--line-soft);border-radius:8px;margin-bottom:8px;min-height:1.5em;word-break:break-all}.calc-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:6px}.calc-grid button{font:inherit;font-size:1.05rem;font-weight:600;padding:9px 0;border-radius:8px;border:1px solid var(--line);background:var(--panel-opaque);cursor:pointer}.calc-grid button:hover{background:var(--line-soft)}.calc-head{display:flex;justify-content:space-between;align-items:center;margin-bottom:6px;cursor:move;font-weight:650;font-size:.85rem;color:var(--ink-2)}.result-q{border:1px solid var(--line-soft);border-radius:12px;padding:16px 18px;margin-bottom:14px;background:var(--panel-opaque)}.result-q.correct{border-left:4px solid var(--ok)}.result-q.partial{border-left:4px solid var(--warn)}.result-q.wrong{border-left:4px solid var(--bad)}.tutor{background:rgba(47,111,237,.06);border:1px solid rgba(47,111,237,.25);border-radius:10px;padding:12px 16px;margin-top:10px}.tutor h4{margin:0 0 6px;color:var(--accent);font-size:.9rem}details.explain summary{cursor:pointer;font-weight:650;color:var(--accent);margin-top:8px}@media (max-width:900px){.exam-layout{grid-template-columns:1fr}.topbar-inner{flex-wrap:wrap}.calc{position:fixed;right:10px;top:auto;bottom:10px}}@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}.visually-hidden{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}.mt0{margin-top:0}.mb0{margin-bottom:0}.muted{color:var(--ink-3)}.small{font-size:.85rem}.landing-hero{text-align:center;padding:60px 20px 30px}.landing-hero h1{font-size:2.4rem}.landing-hero p{max-width:620px;margin:0 auto 24px;color:var(--ink-2);font-size:1.08rem}