@font-face{font-family:Raleway;font-weight:400;font-display:swap;src:url(assets/Raleway-400-latin.woff2) format("woff2")}
@font-face{font-family:Raleway;font-weight:600;font-display:swap;src:url(assets/Raleway-600-latin.woff2) format("woff2")}
@font-face{font-family:Raleway;font-weight:700;font-display:swap;src:url(assets/Raleway-700-latin.woff2) format("woff2")}
@font-face{font-family:Raleway;font-weight:800;font-display:swap;src:url(assets/Raleway-800-latin.woff2) format("woff2")}

:root{
  --navy:#1F4458;--navy-900:#0F2531;--navy-950:#0A1A23;--navy-700:#2A5670;
  --teal:#31988D;--teal-700:#23786F;--mint:#8FE3D6;--mint-100:#E4F8F4;
  --amber:#FFB839;--amber-100:#FFF3DA;--purple:#6E4F8F;--purple-100:#F1ECF7;--purple-300:#B9A3D3;
  --red:#C8474B;--red-100:#FBE9E9;--green:#2E8B57;--green-100:#E3F4EA;
  --bg:#F5F7F8;--card:#FFFFFF;--ink:#16303E;--ink-2:#4B6371;--line:#E1E8EC;
  --radius:16px;--shadow:0 1px 2px rgba(15,37,49,.06),0 8px 24px rgba(15,37,49,.06);
  --shadow-lg:0 2px 4px rgba(15,37,49,.08),0 18px 48px rgba(15,37,49,.14);
  --font:Raleway,system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --ease:cubic-bezier(.2,.8,.2,1);
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;font-family:var(--font);font-variant-numeric:lining-nums tabular-nums;color:var(--ink);background:var(--bg);line-height:1.5;font-size:16px;min-height:100vh;display:flex;flex-direction:column}
img{max-width:100%;display:block}
button,input,select{font:inherit;color:inherit}
a{color:var(--teal-700)}
.skip{position:absolute;left:-999px;top:8px;background:var(--amber);color:var(--navy-900);padding:8px 14px;border-radius:8px;z-index:100;font-weight:700}
.skip:focus{left:8px}
:focus-visible{outline:3px solid var(--amber);outline-offset:2px;border-radius:6px}
.muted{color:var(--ink-2)}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}

/* top bar */
.topbar{position:sticky;top:0;z-index:40;display:flex;align-items:center;justify-content:space-between;gap:12px;padding:10px max(16px,env(safe-area-inset-left));background:rgba(31,68,88,.97);backdrop-filter:saturate(1.4) blur(10px);color:#fff;border-bottom:1px solid rgba(143,227,214,.18)}
.brand{display:flex;align-items:center;gap:10px;color:#fff;text-decoration:none;min-width:0}
.brand img{width:40px;height:40px;border-radius:50%;box-shadow:0 0 0 2px rgba(143,227,214,.35)}
.brand-text{display:flex;flex-direction:column;line-height:1.1;min-width:0}
.brand-top{font-size:11px;letter-spacing:.18em;text-transform:uppercase;color:var(--mint);font-weight:700}
.brand-main{font-weight:800;font-size:17px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.nav{display:flex;gap:4px}
.nav a{display:flex;align-items:center;gap:7px;padding:9px 14px;border-radius:999px;color:#DCEBEF;text-decoration:none;font-weight:700;font-size:14px;transition:background .2s var(--ease),color .2s}
.nav a svg{width:18px;height:18px;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round}
.nav a:hover{background:rgba(255,255,255,.08);color:#fff}
.nav a[aria-current=page]{background:var(--mint);color:var(--navy-900)}

main{flex:1;width:100%;outline:none}
.wrap{max-width:1240px;margin:0 auto;padding:24px 16px 48px}
.footer{padding:28px 16px 40px;text-align:center;font-size:13px;color:var(--ink-2);border-top:1px solid var(--line);background:#fff}
.footer p{margin:4px auto;max-width:720px}

/* hero */
.hero{background:radial-gradient(1200px 400px at 85% -10%,rgba(110,79,143,.55),transparent 60%),radial-gradient(900px 380px at 0% 120%,rgba(49,152,141,.45),transparent 60%),var(--navy);color:#fff;padding:36px 16px 84px}
.hero-in{max-width:1240px;margin:0 auto}
.eyebrow{display:inline-flex;align-items:center;gap:8px;font-size:12px;font-weight:800;letter-spacing:.16em;text-transform:uppercase;color:var(--mint);background:rgba(143,227,214,.1);border:1px solid rgba(143,227,214,.25);padding:6px 12px;border-radius:999px}
.eyebrow i{width:8px;height:8px;border-radius:50%;background:var(--purple-300);box-shadow:0 0 0 3px rgba(185,163,211,.25)}
.hero h1{font-size:clamp(28px,5vw,48px);line-height:1.08;margin:14px 0 10px;font-weight:800;letter-spacing:-.01em}
.hero h1 span{color:var(--mint)}
.hero p{max-width:640px;color:#CFE0E6;margin:0;font-size:17px}
.stats{display:flex;flex-wrap:wrap;gap:10px;margin-top:22px}
.stat{background:rgba(255,255,255,.07);border:1px solid rgba(255,255,255,.12);border-radius:14px;padding:10px 14px;min-width:110px}
.stat b{display:block;font-size:22px;font-weight:800;color:#fff}
.stat span{font-size:12px;color:#BFD4DB;font-weight:600}
.hero-actions{display:flex;flex-wrap:wrap;gap:10px;margin-top:22px}

/* buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:0;border-radius:12px;padding:12px 18px;font-weight:700;font-size:15px;cursor:pointer;text-decoration:none;transition:transform .15s var(--ease),box-shadow .2s,background .2s;min-height:44px}
.btn:active{transform:scale(.97)}
.btn-primary{background:var(--teal);color:#fff;box-shadow:0 6px 18px rgba(49,152,141,.35)}
.btn-primary:hover{background:var(--teal-700)}
.btn-amber{background:var(--amber);color:var(--navy-900);box-shadow:0 6px 18px rgba(255,184,57,.3)}
.btn-ghost{background:rgba(255,255,255,.1);color:#fff;border:1px solid rgba(255,255,255,.2)}
.btn-ghost:hover{background:rgba(255,255,255,.16)}
.btn-line{background:#fff;color:var(--navy);border:1.5px solid var(--line)}
.btn-line:hover{border-color:var(--teal)}
.btn[disabled]{opacity:.45;cursor:not-allowed}
.btn svg{width:18px;height:18px;fill:none;stroke:currentColor;stroke-width:2.2;stroke-linecap:round;stroke-linejoin:round}

/* toolbar */
.toolbar{max-width:1240px;margin:-56px auto 0;padding:0 16px;position:relative;z-index:2}
.toolbar-card{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow-lg);padding:14px;display:grid;gap:12px}
.search{position:relative}
.search svg{position:absolute;left:14px;top:50%;transform:translateY(-50%);width:20px;height:20px;stroke:var(--ink-2);fill:none;stroke-width:2}
.search input{width:100%;padding:13px 14px 13px 44px;border-radius:12px;border:1.5px solid var(--line);background:var(--bg);font-size:16px;transition:border-color .2s,background .2s}
.search input:focus{outline:none;border-color:var(--teal);background:#fff}
.filters{display:flex;flex-wrap:wrap;gap:8px;align-items:center}
.select{appearance:none;-webkit-appearance:none;padding:10px 34px 10px 12px;border-radius:10px;border:1.5px solid var(--line);background:#fff url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8'%3E%3Cpath d='M1 1l5 5 5-5' fill='none' stroke='%231F4458' stroke-width='2'/%3E%3C/svg%3E") no-repeat right 12px center;font-weight:600;font-size:14px;min-height:42px;cursor:pointer;max-width:100%}
.select:focus{outline:none;border-color:var(--teal)}
.chips{display:flex;gap:6px;overflow-x:auto;scrollbar-width:none;padding:2px}
.chips::-webkit-scrollbar{display:none}
.chip{flex:none;border:1.5px solid var(--line);background:#fff;border-radius:999px;padding:7px 13px;font-size:13px;font-weight:700;color:var(--ink-2);cursor:pointer;transition:all .18s var(--ease);white-space:nowrap}
.chip:hover{border-color:var(--teal);color:var(--navy)}
.chip[aria-pressed=true]{background:var(--navy);border-color:var(--navy);color:#fff}
.result-line{display:flex;justify-content:space-between;align-items:center;margin:22px 2px 12px;font-size:14px;color:var(--ink-2);font-weight:600}
.linkbtn{background:none;border:0;color:var(--teal-700);font-weight:700;cursor:pointer;padding:4px}

/* grid */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:16px}
.card{position:relative;background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);overflow:hidden;text-decoration:none;color:inherit;display:flex;flex-direction:column;transition:transform .25s var(--ease),box-shadow .25s var(--ease);animation:rise .45s var(--ease) both}
.card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg)}
.card:focus-visible{outline-offset:3px}
.thumb{position:relative;aspect-ratio:4/3;background:#fff;display:grid;place-items:center;overflow:hidden;border-bottom:1px solid var(--line)}
.thumb img{width:88%;height:88%;object-fit:contain;transition:transform .5s var(--ease)}
.card:hover .thumb img{transform:scale(1.06)}
.num{position:absolute;left:10px;top:10px;background:var(--navy);color:#fff;font-weight:800;font-size:13px;border-radius:9px;padding:4px 9px;min-width:34px;text-align:center}
.stain{position:absolute;right:10px;top:10px;font-size:11px;font-weight:800;border-radius:999px;padding:4px 9px;background:var(--purple-100);color:var(--purple)}
.stain.he{background:#F4E8F1;color:#8A3E74}
.mastery{position:absolute;right:10px;bottom:10px;width:11px;height:11px;border-radius:50%;background:#D5DEE3;box-shadow:0 0 0 3px #fff}
.mastery.m1{background:var(--amber)}.mastery.m2{background:var(--teal)}
.card-body{padding:12px 14px 14px;display:flex;flex-direction:column;gap:8px;flex:1}
.card h3{font-size:15px;line-height:1.3;margin:0;font-weight:700}
.tags{display:flex;flex-wrap:wrap;gap:5px;margin-top:auto}
.tag{font-size:11px;font-weight:700;border-radius:6px;padding:3px 7px;background:var(--bg);color:var(--ink-2)}
.tag.cat{background:var(--mint-100);color:var(--teal-700)}
.tag.wk{background:var(--amber-100);color:#8A5A00}
.empty{padding:48px 16px;text-align:center;color:var(--ink-2);background:#fff;border-radius:var(--radius);box-shadow:var(--shadow)}
@keyframes rise{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}

/* viewer */
.viewer-page{background:var(--navy-950);color:#E6F0F3;min-height:calc(100vh - 61px)}
.vp-grid{display:grid;grid-template-columns:minmax(0,1fr) 400px;min-height:calc(100vh - 61px)}
.stage-col{display:flex;flex-direction:column;min-width:0}
.stage-head{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:12px 16px;border-bottom:1px solid rgba(255,255,255,.06)}
.crumb{display:flex;align-items:center;gap:8px;min-width:0}
.crumb a{color:var(--mint);text-decoration:none;font-weight:700;font-size:14px;display:inline-flex;align-items:center;gap:4px;flex:none}
.crumb a svg{width:16px;height:16px;fill:none;stroke:currentColor;stroke-width:2.4}
.crumb h1{font-size:17px;margin:0;font-weight:800;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;color:#fff}
.crumb .n{flex:none;background:var(--purple);color:#fff;border-radius:8px;font-size:13px;font-weight:800;padding:3px 8px}
.pager{display:flex;gap:6px;flex:none}
.icon-btn{width:42px;height:42px;display:grid;place-items:center;border-radius:12px;border:1px solid rgba(255,255,255,.12);background:rgba(255,255,255,.05);color:#fff;cursor:pointer;transition:background .2s,transform .12s}
.icon-btn:hover{background:rgba(255,255,255,.12)}
.icon-btn:active{transform:scale(.94)}
.icon-btn svg{width:20px;height:20px;fill:none;stroke:currentColor;stroke-width:2.2;stroke-linecap:round;stroke-linejoin:round}
.icon-btn[disabled]{opacity:.3;cursor:default}
.stage{position:relative;flex:1;min-height:360px;overflow:hidden;touch-action:none;cursor:grab;
  background:radial-gradient(circle at 50% 45%,#1C3C4E 0%,#0D212C 55%,#07131A 100%)}
.stage.grabbing{cursor:grabbing}
.stage::after{content:"";position:absolute;inset:0;pointer-events:none;box-shadow:inset 0 0 120px rgba(0,0,0,.55)}
.stage-img{max-width:none;max-height:none;position:absolute;left:0;top:0;transform-origin:0 0;will-change:transform;user-select:none;-webkit-user-drag:none;border-radius:6px;box-shadow:0 20px 60px rgba(0,0,0,.45);background:#fff;opacity:0;transition:opacity .3s}
.stage-img.ready{opacity:1}
.stage-img.anim{transition:transform .28s var(--ease),opacity .3s}
.hud{position:absolute;z-index:2;display:flex;gap:6px}
.hud-tr{right:12px;top:12px;flex-direction:column}
.hud-bl{left:12px;bottom:12px;align-items:center}
.zoom-pill{background:rgba(10,26,35,.8);border:1px solid rgba(255,255,255,.12);border-radius:999px;padding:6px 12px;font-size:13px;font-weight:800;color:var(--mint);min-width:62px;text-align:center}
.seg{display:inline-flex;background:rgba(10,26,35,.8);border:1px solid rgba(255,255,255,.12);border-radius:999px;padding:3px}
.seg button{border:0;background:none;color:#BFD4DB;font-weight:700;font-size:12.5px;padding:6px 11px;border-radius:999px;cursor:pointer}
.seg button[aria-pressed=true]{background:var(--mint);color:var(--navy-900)}
.hint{position:absolute;left:50%;bottom:14px;transform:translateX(-50%);z-index:2;background:rgba(10,26,35,.8);border:1px solid rgba(255,255,255,.1);color:#BFD4DB;font-size:12.5px;font-weight:600;border-radius:999px;padding:6px 12px;pointer-events:none;transition:opacity .6s;white-space:nowrap}
.res-note{font-size:12px;color:#8FA9B4;padding:8px 16px 12px}

.panel{background:#fff;color:var(--ink);overflow-y:auto;max-height:calc(100vh - 61px);position:sticky;top:61px}
.panel-in{padding:20px 20px 28px;display:grid;gap:18px}
.dx-label{font-size:11px;letter-spacing:.14em;text-transform:uppercase;font-weight:800;color:var(--purple)}
.dx{font-size:22px;line-height:1.2;font-weight:800;margin:4px 0 0;color:var(--navy)}
.meta{display:grid;grid-template-columns:1fr 1fr;gap:8px}
.meta div{background:var(--bg);border-radius:12px;padding:9px 11px}
.meta dt{font-size:11px;font-weight:800;color:var(--ink-2);text-transform:uppercase;letter-spacing:.08em}
.meta dd{margin:2px 0 0;font-weight:700;font-size:14px}
.box{border:1px solid var(--line);border-radius:14px;padding:14px}
.box h2{font-size:13px;margin:0 0 8px;text-transform:uppercase;letter-spacing:.1em;font-weight:800;color:var(--teal-700);display:flex;align-items:center;gap:8px}
.box h2 svg{width:17px;height:17px;fill:none;stroke:currentColor;stroke-width:2.2}
.box p{margin:0;font-size:15px}
.box.look{border-color:rgba(110,79,143,.25);background:linear-gradient(180deg,var(--purple-100),#fff 70%)}
.box.look h2{color:var(--purple)}
.checklist{list-style:none;margin:0;padding:0;display:grid;gap:6px}
.checklist label{display:flex;gap:10px;align-items:flex-start;padding:8px 10px;border-radius:10px;cursor:pointer;font-weight:600;font-size:15px;transition:background .15s}
.checklist label:hover{background:var(--bg)}
.checklist input{appearance:none;-webkit-appearance:none;flex:none;width:22px;height:22px;border-radius:7px;border:2px solid #B9C8D0;margin:0;display:grid;place-items:center;cursor:pointer;transition:all .18s var(--ease)}
.checklist input:checked{background:var(--teal);border-color:var(--teal)}
.checklist input:checked::after{content:"";width:10px;height:6px;border-left:2.5px solid #fff;border-bottom:2.5px solid #fff;transform:rotate(-45deg) translate(1px,-1px)}
.checklist input:checked + span{color:var(--ink-2);text-decoration:line-through;text-decoration-color:rgba(49,152,141,.5)}
.qa{margin:0;display:grid;gap:0}
.qa details{border-top:1px solid var(--line)}
.qa details:first-child{border-top:0}
.qa summary{cursor:pointer;list-style:none;padding:10px 26px 10px 0;font-weight:600;font-size:14.5px;position:relative}
.qa summary::-webkit-details-marker{display:none}
.qa summary::after{content:"+";position:absolute;right:4px;top:8px;font-weight:800;color:var(--teal);font-size:18px;transition:transform .2s}
.qa details[open] summary::after{transform:rotate(45deg)}
.qa .ans{padding:0 0 12px;color:var(--teal-700);font-weight:700;font-size:14.5px}
.caveat{background:var(--amber-100);border:1px solid #F5D796;border-radius:12px;padding:10px 12px;font-size:13.5px;color:#6B4A00}
.panel-actions{display:flex;gap:8px;flex-wrap:wrap}
.panel-actions .btn{flex:1}

/* quiz */
.page-head{background:var(--navy);color:#fff;padding:28px 16px 70px;background-image:radial-gradient(800px 300px at 90% 0,rgba(110,79,143,.5),transparent 60%)}
.page-head .hero-in h1{margin:10px 0 6px;font-size:clamp(26px,4vw,38px);font-weight:800}
.page-head p{margin:0;color:#CFE0E6;max-width:640px}
.pull{max-width:1000px;margin:-48px auto 0;padding:0 16px 48px;position:relative}
.modes{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:14px}
.mode{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow-lg);padding:18px;display:flex;flex-direction:column;gap:10px;border:2px solid transparent;transition:border-color .2s,transform .2s var(--ease)}
.mode:hover{border-color:var(--mint)}
.mode .ic{width:44px;height:44px;border-radius:12px;display:grid;place-items:center;background:var(--mint-100);color:var(--teal-700)}
.mode .ic svg{width:22px;height:22px;fill:none;stroke:currentColor;stroke-width:2.2;stroke-linecap:round;stroke-linejoin:round}
.mode.exam .ic{background:var(--amber-100);color:#A36A00}
.mode h2{font-size:18px;margin:0;font-weight:800}
.mode p{margin:0;font-size:14px;color:var(--ink-2)}
.mode .select{width:100%}
.mode .btn{margin-top:auto}
.best{display:flex;gap:10px;flex-wrap:wrap;margin-top:18px}
.best div{background:#fff;border-radius:14px;box-shadow:var(--shadow);padding:12px 16px;flex:1;min-width:150px}
.best b{font-size:22px;display:block;color:var(--navy)}
.best span{font-size:13px;color:var(--ink-2);font-weight:600}

.qwrap{max-width:1100px;margin:0 auto;padding:20px 16px 48px}
.qtop{display:flex;align-items:center;gap:12px;margin-bottom:14px}
.progress{flex:1;height:8px;background:#DDE6EA;border-radius:999px;overflow:hidden}
.progress i{display:block;height:100%;background:linear-gradient(90deg,var(--teal),var(--mint));border-radius:999px;transition:width .4s var(--ease)}
.qcount{font-weight:800;font-size:14px;color:var(--ink-2);white-space:nowrap}
.qgrid{display:grid;grid-template-columns:minmax(0,1.05fr) minmax(0,1fr);gap:18px;align-items:start}
.qimg{background:radial-gradient(circle at 50% 45%,#1C3C4E,#0A1A23);border-radius:var(--radius);aspect-ratio:1/1;display:grid;place-items:center;padding:18px;position:relative;overflow:hidden;cursor:zoom-in}
.qimg img{max-height:100%;max-width:100%;object-fit:contain;border-radius:6px;background:#fff;box-shadow:0 12px 40px rgba(0,0,0,.4)}
.qimg .zoomhint{position:absolute;right:10px;bottom:10px;font-size:12px;font-weight:700;color:#BFD4DB;background:rgba(10,26,35,.75);padding:4px 10px;border-radius:999px}
.qcard{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:18px}
.qkind{display:inline-block;font-size:11px;font-weight:800;text-transform:uppercase;letter-spacing:.12em;color:var(--purple);background:var(--purple-100);border-radius:999px;padding:4px 10px}
.qstem{font-size:19px;font-weight:700;margin:10px 0 14px;line-height:1.35}
.opts{display:grid;gap:8px;margin:0;padding:0;list-style:none}
.opt{width:100%;display:flex;gap:12px;align-items:center;text-align:left;border:1.5px solid var(--line);background:#fff;border-radius:12px;padding:11px 12px;cursor:pointer;font-weight:600;font-size:15px;transition:border-color .15s,background .15s,transform .12s;min-height:50px}
.opt:hover:not([disabled]){border-color:var(--teal);background:#FAFEFD}
.opt:active:not([disabled]){transform:scale(.99)}
.opt .L{flex:none;width:30px;height:30px;border-radius:9px;display:grid;place-items:center;background:var(--bg);font-weight:800;font-size:14px;color:var(--navy)}
.opt.correct{border-color:var(--green);background:var(--green-100)}
.opt.correct .L{background:var(--green);color:#fff}
.opt.wrong{border-color:var(--red);background:var(--red-100);animation:shake .35s}
.opt.wrong .L{background:var(--red);color:#fff}
.opt[disabled]{cursor:default}
.opt.dim{opacity:.55}
@keyframes shake{25%{transform:translateX(-4px)}75%{transform:translateX(4px)}}
.feedback{margin-top:14px;border-radius:12px;padding:12px 14px;font-size:14.5px;animation:rise .3s var(--ease)}
.feedback.ok{background:var(--green-100);border:1px solid #BFE3CD}
.feedback.no{background:var(--red-100);border:1px solid #F0C6C7}
.feedback b{display:block;margin-bottom:4px}
.feedback a{font-weight:700}
.qnav{display:flex;justify-content:flex-end;gap:8px;margin-top:14px}

.summary{max-width:860px;margin:0 auto;padding:24px 16px 48px}
.score-card{background:var(--navy);color:#fff;border-radius:22px;padding:28px 20px;text-align:center;box-shadow:var(--shadow-lg);background-image:radial-gradient(600px 240px at 90% 0,rgba(110,79,143,.55),transparent 60%)}
.ring{--p:0;width:150px;height:150px;border-radius:50%;margin:6px auto 14px;display:grid;place-items:center;background:conic-gradient(var(--mint) calc(var(--p)*1%),rgba(255,255,255,.12) 0);transition:--p 1s}
.ring div{width:120px;height:120px;border-radius:50%;background:var(--navy);display:grid;place-items:center;font-size:34px;font-weight:800}
.score-card h1{margin:0;font-size:26px}
.score-card p{margin:6px 0 0;color:#CFE0E6}
.score-actions{display:flex;gap:10px;justify-content:center;flex-wrap:wrap;margin-top:18px}
.review{margin-top:22px;display:grid;gap:12px}
.review h2{font-size:18px;margin:8px 0 0}
.rv{background:#fff;border-radius:14px;box-shadow:var(--shadow);padding:14px;display:grid;grid-template-columns:84px 1fr;gap:12px}
.rv img{width:84px;height:84px;object-fit:contain;background:#fff;border-radius:10px;border:1px solid var(--line)}
.rv p{margin:2px 0;font-size:14px}
.rv .you{color:var(--red);font-weight:700}
.rv .right{color:var(--green);font-weight:700}

/* flashcards */
.fc-wrap{max-width:720px;margin:0 auto;padding:20px 16px 48px}
.fc-bar{display:flex;gap:8px;flex-wrap:wrap;align-items:center;margin-bottom:14px}
.fc-bar .select{flex:1;min-width:160px}
.flip{perspective:1400px;cursor:pointer;-webkit-tap-highlight-color:transparent}
.flip-in{position:relative;transition:transform .6s var(--ease);transform-style:preserve-3d;min-height:min(78vh,620px)}
.flip.on .flip-in{transform:rotateY(180deg)}
.face{position:absolute;inset:0;backface-visibility:hidden;-webkit-backface-visibility:hidden;border-radius:22px;overflow:hidden;box-shadow:var(--shadow-lg)}
.front{background:radial-gradient(circle at 50% 45%,#1C3C4E,#07131A);display:flex;flex-direction:column;align-items:center;justify-content:center;padding:20px}
.front img{max-height:calc(min(78vh,620px) - 110px);max-width:100%;object-fit:contain;border-radius:8px;background:#fff;box-shadow:0 18px 50px rgba(0,0,0,.5)}
.front .tap{margin-top:16px;color:var(--mint);font-weight:700;font-size:14px;display:flex;align-items:center;gap:8px}
.back{transform:rotateY(180deg);background:#fff;padding:24px;display:flex;flex-direction:column;gap:14px;overflow-y:auto}
.back .num{position:static;display:inline-block;width:max-content}
.back h2{margin:0;font-size:26px;line-height:1.15;color:var(--navy);font-weight:800}
.back .sub{margin:0;color:var(--purple);font-weight:700}
.back ol{margin:0;padding:0;list-style:none;display:grid;gap:8px;counter-reset:f}
.back li{counter-increment:f;display:flex;gap:10px;align-items:flex-start;background:var(--bg);border-radius:12px;padding:10px 12px;font-weight:600}
.back li::before{content:counter(f);flex:none;width:24px;height:24px;border-radius:50%;background:var(--teal);color:#fff;display:grid;place-items:center;font-size:13px;font-weight:800}
.back .mini{display:flex;gap:10px;align-items:center}
.back .mini img{width:64px;height:64px;object-fit:contain;border:1px solid var(--line);border-radius:10px}
.fc-actions{display:flex;gap:10px;margin-top:14px}
.fc-actions .btn{flex:1}
.fc-count{font-weight:800;color:var(--ink-2);font-size:14px;background:#fff;border-radius:10px;padding:10px 12px;box-shadow:var(--shadow)}

/* lightbox */
.lightbox{position:fixed;inset:0;z-index:80;background:rgba(5,14,19,.92);display:flex;align-items:center;justify-content:center;animation:fade .2s}
.lightbox .stage{position:absolute;inset:0;background:none}
.lightbox .close{position:absolute;right:14px;top:14px;z-index:3}
@keyframes fade{from{opacity:0}}

#toast{position:fixed;left:50%;bottom:22px;transform:translate(-50%,20px);background:var(--navy-900);color:#fff;padding:10px 16px;border-radius:12px;font-weight:700;font-size:14px;opacity:0;pointer-events:none;transition:all .3s var(--ease);z-index:90}
#toast.show{opacity:1;transform:translate(-50%,0)}

/* responsive */
@media (max-width:980px){
  .vp-grid{grid-template-columns:1fr}
  .stage{min-height:62vh;flex:none;height:62vh}
  .panel{max-height:none;position:static}
  .qgrid{grid-template-columns:1fr}
  .qimg{aspect-ratio:4/3}
}
@media (max-width:640px){
  .brand-main{font-size:15px}
  .brand-top{display:none}
  .topbar{backdrop-filter:none;-webkit-backdrop-filter:none;background:var(--navy)}
  .nav{position:fixed;left:0;right:0;bottom:0;z-index:50;background:rgba(15,37,49,.98);justify-content:space-around;padding:6px 8px calc(6px + env(safe-area-inset-bottom));border-top:1px solid rgba(143,227,214,.18)}
  .nav a{flex-direction:column;gap:2px;font-size:11px;padding:6px 14px;border-radius:12px}
  body{padding-bottom:64px}
  #toast{bottom:84px}
  .hero{padding:26px 16px 76px}
  .hero p{font-size:15px}
  .grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
  .card h3{font-size:13.5px}
  .card-body{padding:10px}
  .tag{font-size:10px}
  .stat{min-width:0;flex:1}
  .stage{height:56vh;min-height:300px}
  .crumb h1{font-size:15px}
  .qstem{font-size:17px}
  .rv{grid-template-columns:64px 1fr}.rv img{width:64px;height:64px}
  .hint{display:none}
}
@media (prefers-reduced-motion:reduce){*,*::before,*::after{animation:none!important;transition:none!important}}