:root{
  --navy:#1f3a68; --navy2:#2c4f8c; --gold:#f2b134; --bg:#f4f6fb; --card:#fff; --ink:#1d2433; --muted:#5d6779;
  --line:#dfe4ee; --green:#1e9e62; --green-bg:#e7f7ef; --red:#d64545; --red-bg:#fdeeee; --amber:#d98a00; --radius:14px;
  --shadow:0 2px 10px rgba(31,58,104,.08);
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;font-family:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;background:var(--bg);color:var(--ink);line-height:1.5;font-size:16px}
a{color:var(--navy2)}
h1{font-size:1.6rem;margin:.2em 0 .3em;color:var(--navy)} h2{color:var(--navy);font-size:1.25rem} h3{margin:.3em 0;color:var(--navy)}
.muted{color:var(--muted)} .small{font-size:.88rem} .center{text-align:center;margin-top:10px}
code{background:#eef1f7;padding:1px 5px;border-radius:5px}

/* top bar */
.topbar{position:sticky;top:0;z-index:20;display:flex;align-items:center;gap:12px;padding:10px 18px;background:linear-gradient(90deg,var(--navy),var(--navy2));color:#fff;box-shadow:0 2px 8px rgba(0,0,0,.15)}
.brand{display:flex;align-items:center;gap:10px;color:#fff;text-decoration:none;font-weight:700;font-size:1.05rem;margin-right:auto}
.brand em{font-style:normal;color:var(--gold)}
.logo{width:32px;height:32px}
nav{display:flex;gap:4px}
nav a{color:#dfe7f7;text-decoration:none;padding:8px 12px;border-radius:9px;font-weight:600;font-size:.95rem}
nav a:hover{background:rgba(255,255,255,.12);color:#fff}
nav a.active{background:rgba(255,255,255,.18);color:#fff}
.menu-btn{display:none;background:none;border:1px solid rgba(255,255,255,.4);color:#fff;font-size:1.3rem;border-radius:8px;padding:2px 10px;cursor:pointer}
main{max-width:980px;margin:0 auto;padding:20px 16px 40px;outline:none}
.foot{text-align:center;color:var(--muted);padding:20px;font-size:.9rem}

/* cards & layout */
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:18px;box-shadow:var(--shadow);margin-bottom:14px}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(270px,1fr));gap:14px}
.grid.two{grid-template-columns:repeat(auto-fill,minmax(300px,1fr));margin-top:10px}
.grid .card{margin-bottom:0}
.section-title{margin:26px 0 12px}
.row{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin-top:10px}

.hero{background:linear-gradient(135deg,#fff 0%,#eef3ff 100%);border:1px solid var(--line);border-radius:18px;padding:24px;box-shadow:var(--shadow);position:relative;overflow:hidden}
.hero::after{content:"";position:absolute;right:-40px;top:-30px;width:220px;height:220px;background:conic-gradient(from 30deg,rgba(242,177,52,.25),rgba(44,79,140,.18),rgba(242,177,52,.25));clip-path:polygon(50% 0,100% 100%,0 100%);opacity:.8}
.hero h1{font-size:1.9rem}
.hero p{max-width:600px;position:relative;z-index:1}
.hero-stats{display:flex;gap:22px;margin-top:10px;position:relative;z-index:1}
.hero-stats b{display:block;font-size:1.6rem;color:var(--navy)} .hero-stats span{color:var(--muted);font-size:.85rem}
.banner{margin:14px 0;padding:12px 16px;border-radius:12px;background:#fff7e3;border:1px solid #f3d58b;display:flex;flex-wrap:wrap;align-items:center;gap:8px}

.unit-card{display:flex;flex-direction:column}
.unit-card p{color:var(--muted);flex:1;margin:.3em 0 .8em}
.unit-top{display:flex;justify-content:space-between;align-items:center}
.unit-icon{font-size:1.7rem} .unit-num{font-size:.78rem;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.unit-card.mixed{background:linear-gradient(135deg,#fffaf0,#fff);border-color:#f3d58b}
.meta{display:flex;justify-content:space-between;align-items:center;font-size:.88rem;color:var(--muted);margin-bottom:12px}
.link-card{text-decoration:none;color:inherit;transition:transform .15s} .link-card:hover{transform:translateY(-2px)} .link-card p{color:var(--muted);margin:0}

.pill{display:inline-block;padding:2px 10px;border-radius:999px;background:#eef1f7;font-weight:600;font-size:.82rem;color:var(--muted)}
.pill.great,.great{color:var(--green)} .pill.great{background:var(--green-bg)}
.pill.good{background:#e8f1ff;color:var(--navy2)} .good{color:var(--navy2)}
.pill.ok{background:#fff3db;color:var(--amber)} .ok{color:var(--amber)}
.pill.low{background:var(--red-bg);color:var(--red)} .low{color:var(--red)}

/* buttons & forms */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;background:var(--navy);color:#fff;border:2px solid var(--navy);padding:10px 18px;border-radius:11px;font-weight:700;font-size:.98rem;text-decoration:none;cursor:pointer;font-family:inherit;min-height:44px}
.btn:hover{background:var(--navy2);border-color:var(--navy2)}
.btn.accent{background:var(--gold);border-color:var(--gold);color:#2a1d00} .btn.accent:hover{background:#e6a21d}
.btn.ghost{background:#fff;color:var(--navy);border-color:var(--line)} .btn.ghost:hover{border-color:var(--navy2)}
.btn.small{padding:6px 12px;font-size:.88rem;min-height:36px}
.btn.big{width:100%;font-size:1.1rem;padding:14px}
.btn.danger{color:var(--red)}
.btn:disabled{opacity:.45;cursor:default}
label{display:block;font-weight:600;margin-bottom:12px;color:var(--navy)}
select,input[type=search],textarea,.num-input input{display:block;width:100%;margin-top:6px;padding:11px 12px;border:1.5px solid var(--line);border-radius:10px;font:inherit;background:#fff;color:var(--ink)}
select:focus,input:focus,textarea:focus{outline:none;border-color:var(--navy2);box-shadow:0 0 0 3px rgba(44,79,140,.15)}
label.check{display:flex;gap:8px;align-items:center;font-weight:500}
label.check input{width:20px;height:20px}
.form-grid{display:grid;grid-template-columns:1fr 1fr;gap:0 16px;margin:14px 0}
.form-grid .check{grid-column:1/-1}
.tip{background:#eef3ff;border-radius:10px;padding:10px 12px;font-size:.93rem}
.back{display:inline-block;margin-bottom:10px;text-decoration:none;font-weight:600}

/* exam */
.exam-head{display:flex;justify-content:space-between;align-items:center;margin-bottom:8px}
.timer{font-weight:700;font-variant-numeric:tabular-nums;background:#fff;border:1px solid var(--line);padding:6px 12px;border-radius:999px}
.timer.warn{color:#fff;background:var(--red);border-color:var(--red);animation:pulse 1s infinite}
@keyframes pulse{50%{opacity:.75}}
.progressbar{height:8px;background:#e3e8f2;border-radius:99px;overflow:hidden;margin-bottom:14px}
.progressbar span{display:block;height:100%;background:linear-gradient(90deg,var(--gold),#f6c95e);transition:width .3s}
.qcard{padding:22px}
.prompt{font-size:1.08rem;margin-bottom:12px}
.prompt.small{font-size:.95rem}
.tag{display:inline-block;font-size:.75rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--navy2);background:#e8f1ff;padding:2px 8px;border-radius:6px;margin-bottom:8px}
.honors{display:inline-block;font-size:.72rem;font-weight:800;text-transform:uppercase;letter-spacing:.05em;color:#7a4b00;background:#ffe9b8;padding:1px 7px;border-radius:6px;margin-right:4px}
.figure{display:flex;justify-content:center;margin:8px 0 16px}
.fig{width:100%;max-width:340px;height:auto;background:#fbfcff;border:1px solid var(--line);border-radius:12px}
.figure.small .fig{max-width:240px}
.fig .ln{stroke:#1d2433;stroke-width:2;fill:none} .fig .ln.dash{stroke-dasharray:5 4;stroke:#7a8496}
.fig .tick{stroke:#d64545;stroke-width:2}
.fig .pt{fill:#1d2433} .fig .lbl{font:italic 600 15px Georgia,serif;fill:var(--navy)}
.fig .note{font:13px system-ui,sans-serif;fill:#333} .fig .ang{font:600 13px system-ui,sans-serif;fill:#b0371b}
.fig .arrowhead{fill:#1d2433} .fig .fill{fill:#eef3ff} .fig .ra{fill:none;stroke:#1d2433;stroke-width:1.5}
.choices{display:grid;gap:10px}
.choice{display:flex;align-items:flex-start;gap:12px;padding:12px 14px;border:2px solid var(--line);border-radius:12px;cursor:pointer;font-weight:500;color:var(--ink);margin:0;transition:border-color .15s,background .15s}
.choice:hover{border-color:#b8c4dc}
.choice input{position:absolute;opacity:0;pointer-events:none}
.choice.selected{border-color:var(--navy2);background:#eef3ff}
.letter{flex:none;width:28px;height:28px;border-radius:50%;background:#eef1f7;display:flex;align-items:center;justify-content:center;font-weight:800;color:var(--navy)}
.choice.selected .letter{background:var(--navy2);color:#fff}
.num-input{display:flex;align-items:center;gap:8px;max-width:280px}
.num-input input{font-size:1.2rem;margin-top:0}
.num-input .unit{font-size:1.3rem;font-weight:700}
.qactions{margin-top:14px}
.navrow{display:flex;justify-content:space-between;gap:10px}
.dots{display:flex;flex-wrap:wrap;gap:6px;justify-content:center;margin-top:16px}
.dot{width:34px;height:34px;border-radius:9px;border:1.5px solid var(--line);background:#fff;font-weight:700;color:var(--muted);cursor:pointer}
.dot.done{background:#e8f1ff;color:var(--navy);border-color:#bcd0f2}
.dot.cur{border-color:var(--navy);box-shadow:0 0 0 2px var(--navy) inset}
.dot.flag{background:#fff3db;border-color:var(--gold)}
table.proof{border-collapse:collapse;margin:10px 0;width:100%;font-size:.95rem}
table.proof th,table.proof td{border:1px solid var(--line);padding:6px 9px;text-align:left;vertical-align:top}
table.proof th{background:#eef1f7}
.seg,.ray,.line{position:relative;display:inline-block;padding-top:.2em}
.seg::before,.ray::before,.line::before{content:"";position:absolute;left:0;right:0;top:.12em;border-top:1.5px solid currentColor}
.ray::after{content:"";position:absolute;right:-3px;top:-.08em;border:4px solid transparent;border-left:6px solid currentColor;border-right:0}
.line{padding-top:.45em;line-height:1}.line::after{content:"⟷";position:absolute;left:-2px;right:-2px;top:-.05em;font-size:.7em;line-height:1;text-align:center}
.line::before{display:none}

/* results */
.results-hero{display:flex;gap:24px;align-items:center}
.ring{--p:0;flex:none;width:130px;height:130px;border-radius:50%;background:conic-gradient(currentColor calc(var(--p)*1%),#e6ebf3 0);display:flex;align-items:center;justify-content:center}
.ring span{width:100px;height:100px;border-radius:50%;background:#fff;display:flex;align-items:center;justify-content:center;font-size:1.9rem;font-weight:800;color:var(--ink)}
.results-hero.great .ring{color:var(--green)} .results-hero.good .ring{color:var(--navy2)} .results-hero.ok .ring{color:var(--gold)} .results-hero.low .ring{color:var(--red)}
.results-hero h1,.results-hero .muted,.results-hero p{color:var(--ink)} .results-hero h1{color:var(--navy)}
.big-score{font-size:1.25rem;font-weight:800;margin:0}
.breakdown{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:14px 18px;margin-bottom:14px}
.brow{display:grid;grid-template-columns:170px 1fr 50px;gap:10px;align-items:center;margin:6px 0;font-size:.92rem}
.bar{height:10px;background:#e6ebf3;border-radius:99px;overflow:hidden}
.bar span{display:block;height:100%;background:currentColor}
.review-head{display:flex;justify-content:space-between;align-items:center;margin-top:20px}
.seg-ctrl{display:inline-flex;border:1px solid var(--line);border-radius:10px;overflow:hidden;background:#fff}
.seg-ctrl button{border:0;background:none;padding:8px 14px;font:inherit;font-weight:600;color:var(--muted);cursor:pointer}
.seg-ctrl button.on{background:var(--navy);color:#fff}
.review{border-left:5px solid var(--line)}
.review.right{border-left-color:var(--green)} .review.wrong{border-left-color:var(--red)}
.rhead{display:flex;justify-content:space-between;align-items:center;margin-bottom:8px}
.badge{font-weight:800;font-size:.85rem;padding:3px 10px;border-radius:999px}
.review.right .badge{background:var(--green-bg);color:var(--green)} .review.wrong .badge{background:var(--red-bg);color:var(--red)}
.answers{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:8px 0}
.answers>div{background:#f7f9fc;border-radius:10px;padding:8px 12px}
.answers .lab{display:block;font-size:.75rem;text-transform:uppercase;letter-spacing:.05em;color:var(--muted);font-weight:700}
.answers .ok{color:var(--green);font-weight:700} .answers .bad{color:var(--red);font-weight:700}
.solution{background:#fffbef;border:1px solid #f3e2b0;border-radius:10px;padding:8px 12px;margin:10px 0}
.solution summary{cursor:pointer;font-weight:700;color:#7a4b00}
.solution>div{margin-top:8px}
.solution-inline{background:#fffbef;border-radius:10px;padding:10px;margin-top:10px}

/* progress */
.prog h3{font-size:1.02rem}
.pstats{display:flex;gap:18px;margin:6px 0}
.pstats b{display:block;font-size:1.3rem} .pstats span{font-size:.78rem;color:var(--muted)}
.spark{width:100%;height:60px;margin:4px 0 8px}
.spark polyline{fill:none;stroke:var(--navy2);stroke-width:2.5} .spark circle{fill:var(--gold);stroke:var(--navy2);stroke-width:1.5}
.table-wrap{overflow-x:auto;background:#fff;border:1px solid var(--line);border-radius:var(--radius)}
table.hist{width:100%;border-collapse:collapse;font-size:.93rem}
table.hist th,table.hist td{padding:10px 12px;border-bottom:1px solid var(--line);text-align:left;white-space:nowrap}
table.hist th{background:#f2f5fa;color:var(--muted);font-size:.8rem;text-transform:uppercase}

/* notes */
.search input{font-size:1.05rem}
.chips{display:flex;flex-wrap:wrap;gap:6px;margin:12px 0}
.chip{border:1.5px solid var(--line);background:#fff;border-radius:999px;padding:6px 12px;font:inherit;font-size:.88rem;font-weight:600;color:var(--navy);cursor:pointer}
.chip.on{background:var(--navy);border-color:var(--navy);color:#fff}
.notes dl{margin:0 0 12px} .notes dt{font-weight:700;color:var(--navy);margin-top:12px} .notes dd{margin:2px 0 0;color:#333}
mark{background:#ffe58a;padding:0 2px;border-radius:3px}

/* ask */
.preview{display:none;background:#f7f9fc;border:1px dashed #c8d2e4;border-radius:10px;padding:10px;margin:-4px 0 12px}
.qitem.answered{opacity:.85;border-left:5px solid var(--green)} .qitem.open{border-left:5px solid var(--gold)}
.qitem .badge{background:#fff3db;color:#7a4b00} .qitem.answered .badge{background:var(--green-bg);color:var(--green)}
.qtext{font-size:1.02rem;margin:6px 0 10px}

.toast{position:fixed;left:50%;bottom:24px;transform:translate(-50%,30px);background:var(--ink);color:#fff;padding:10px 18px;border-radius:10px;opacity:0;transition:.25s;z-index:50}
.toast.show{opacity:1;transform:translate(-50%,0)}

@media (max-width:720px){
  .menu-btn{display:block}
  nav{display:none;position:absolute;top:100%;left:0;right:0;flex-direction:column;background:var(--navy);padding:8px}
  nav.open{display:flex}
  .brand span{font-size:.95rem}
  main{padding:14px 12px 30px}
  .hero{padding:18px} .hero h1{font-size:1.5rem}
  .form-grid{grid-template-columns:1fr}
  .results-hero{flex-direction:column;text-align:center} .results-hero .row{justify-content:center}
  .answers{grid-template-columns:1fr}
  .brow{grid-template-columns:110px 1fr 44px}
  .qcard{padding:16px}
}
@media print{.topbar,.foot,.row,.seg-ctrl{display:none}}