:root{
  --bg:#f4f6fb;
  --card:#ffffff;
  --ink:#1f2937;
  --ink-soft:#5b6472;
  --muted:#8b95a5;
  --line:#e7ebf3;
  --brand:#5b8def;
  --brand-d:#3f6fd1;
  --brand-soft:#eaf1fe;
  --ok:#1f9d6b;
  --ok-soft:#e6f6ef;
  --bad:#d9534f;
  --bad-soft:#fbecec;
  --warn:#d99016;
  --shadow:0 6px 22px rgba(31,41,55,.07);
  --shadow-h:0 10px 30px rgba(63,111,209,.16);
  --radius:18px;
}

*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  font-family:'Heebo',system-ui,Arial,sans-serif;
  background:var(--bg);
  color:var(--ink);
  line-height:1.6;
  -webkit-font-smoothing:antialiased;
}
.wrap{max-width:860px;margin:0 auto;padding:0 18px}

/* ---------- header ---------- */
.site-header{
  background:var(--card);
  border-bottom:1px solid var(--line);
  position:sticky;top:0;z-index:20;
}
.header-inner{display:flex;align-items:center;justify-content:space-between;height:64px}
.brand{display:flex;align-items:center;gap:12px;cursor:pointer}
.brand-mark{
  width:42px;height:42px;border-radius:12px;
  background:linear-gradient(135deg,var(--brand),var(--brand-d));
  color:#fff;display:grid;place-items:center;font-size:24px;font-weight:700;
}
.brand-text{display:flex;flex-direction:column;line-height:1.15}
.brand-text strong{font-size:17px}
.brand-text small{color:var(--muted);font-size:12px}
.header-actions{display:flex;align-items:center;gap:8px;flex-wrap:wrap;justify-content:flex-end}
.user-chip{
  background:var(--brand-soft);color:var(--brand-d);border:none;border-radius:99px;
  padding:8px 14px;font-size:14px;font-weight:700;font-family:inherit;cursor:pointer;
  white-space:nowrap;transition:.18s;
}
.user-chip:hover{background:#dce8fd}

/* ---------- confetti ---------- */
.confetti-canvas{position:fixed;inset:0;width:100%;height:100%;pointer-events:none;z-index:9999}

/* ---------- login ---------- */
.login-card{max-width:460px;margin:30px auto;text-align:center;padding:38px 30px}
.login-mark{
  width:64px;height:64px;border-radius:18px;margin:0 auto 18px;
  background:linear-gradient(135deg,var(--brand),var(--brand-d));
  color:#fff;display:grid;place-items:center;font-size:34px;font-weight:700;
}
.login-card h1{font-size:26px;margin:0 0 10px;font-weight:800}
.login-card p{color:var(--ink-soft);margin:0 0 22px;font-size:15.5px}
.login-form{display:flex;flex-direction:column;gap:12px}
.login-row{display:flex;gap:12px}
.login-row input{flex:1;min-width:0}
.login-form input{
  padding:14px 16px;border:1.5px solid var(--line);border-radius:13px;font-size:16px;
  font-family:inherit;text-align:right;transition:.18s;
}
.login-form input:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 3px var(--brand-soft)}
.login-note{display:block;margin-top:14px;color:var(--muted);font-size:13px}

/* ---------- leaderboard ---------- */
.leaderboard-card{padding:30px 26px}
.lb-title{font-size:24px;margin:0 0 4px;text-align:center;font-weight:800}
.lb-sub{text-align:center;color:var(--muted);margin:0 0 22px}
.lb-body{margin-bottom:22px}
.lb-loading,.lb-empty{text-align:center;color:var(--muted);padding:26px}
.lb-table-wrap{overflow-x:auto}
.lb-table{width:100%;border-collapse:collapse;font-size:15px}
.lb-table th{
  text-align:center;padding:12px 8px;color:var(--ink-soft);font-weight:700;font-size:13px;
  border-bottom:2px solid var(--line);white-space:nowrap;
}
.lb-table th:nth-child(2){text-align:right}
.lb-table td{padding:13px 8px;border-bottom:1px solid var(--line)}
.lb-rank{font-weight:800;font-size:16px;width:48px;text-align:center}
.lb-name{font-weight:600;color:var(--ink)}
.lb-num{text-align:center;font-variant-numeric:tabular-nums;font-weight:600;color:var(--ink-soft)}
.lb-correct{color:var(--ok);font-weight:800;font-size:16px}
.lb-me{background:var(--brand-soft)}
.lb-me .lb-name{color:var(--brand-d)}
.lb-you{font-size:12px;color:var(--brand-d);font-weight:700}

/* ---------- buttons ---------- */
.btn-primary{
  background:linear-gradient(135deg,var(--brand),var(--brand-d));
  color:#fff;border:none;border-radius:14px;
  padding:14px 26px;font-size:16px;font-weight:600;font-family:inherit;
  cursor:pointer;transition:.18s;box-shadow:var(--shadow);
}
.btn-primary:hover:not(:disabled){transform:translateY(-1px);box-shadow:var(--shadow-h)}
.btn-primary:disabled{opacity:.45;cursor:not-allowed}
.btn-ghost{
  background:transparent;color:var(--brand-d);border:1px solid var(--line);
  border-radius:12px;padding:11px 18px;font-size:15px;font-weight:600;
  font-family:inherit;cursor:pointer;transition:.18s;
}
.btn-ghost:hover{background:var(--brand-soft);border-color:var(--brand-soft)}

/* ---------- screens ---------- */
.screen{padding:30px 0 60px;animation:fade .35s ease}
@keyframes fade{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}

/* ---------- home ---------- */
.hero{text-align:center;margin-bottom:30px}
.hero h1{font-size:30px;margin:0 0 10px;font-weight:800}
.hero p{color:var(--ink-soft);max-width:620px;margin:0 auto;font-size:16px}

.topics-grid{
  display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:16px;
}
.topic-card{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:22px;cursor:pointer;transition:.2s;text-align:right;
  display:flex;flex-direction:column;gap:10px;box-shadow:var(--shadow);position:relative;overflow:hidden;
}
.topic-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-h);border-color:var(--brand)}
.topic-icon{font-size:30px}
.topic-card h3{margin:0;font-size:18px;font-weight:700;line-height:1.35}
.topic-card .tc-count{color:var(--muted);font-size:13px;font-weight:500}
.topic-card .tc-go{
  margin-top:6px;color:var(--brand-d);font-weight:600;font-size:14px;
}
.topic-num{
  position:absolute;top:14px;left:16px;font-size:13px;font-weight:700;
  color:var(--brand);background:var(--brand-soft);border-radius:8px;
  width:26px;height:26px;display:grid;place-items:center;
}

/* ---------- quiz ---------- */
.quiz-top{margin-bottom:18px}
.quiz-meta{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px;gap:10px}
.quiz-topic-name{font-weight:700;font-size:15px;color:var(--ink)}
.quiz-meta-right{display:flex;align-items:center;gap:12px;flex:0 0 auto}
.quiz-counter{font-size:14px;color:var(--muted);font-weight:600;white-space:nowrap}
.quiz-timer{
  font-size:15px;font-weight:700;color:var(--brand-d);
  background:var(--brand-soft);border-radius:99px;padding:5px 13px;
  font-variant-numeric:tabular-nums;white-space:nowrap;transition:.2s;
}
.quiz-timer.low{color:var(--bad);background:var(--bad-soft);animation:pulse 1s ease-in-out infinite}
@keyframes pulse{0%,100%{transform:scale(1)}50%{transform:scale(1.06)}}
.progress{height:10px;background:#e4e9f2;border-radius:99px;overflow:hidden}
.progress-bar{height:100%;width:0;background:linear-gradient(90deg,var(--brand),var(--brand-d));border-radius:99px;transition:width .35s ease}

.card{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:26px;box-shadow:var(--shadow);
}
.subtopic-tag{
  display:inline-block;font-size:12px;font-weight:600;color:var(--brand-d);
  background:var(--brand-soft);padding:5px 12px;border-radius:99px;margin-bottom:14px;
}
.scenario{
  background:#f8fafd;border-right:4px solid var(--brand);border-radius:10px;
  padding:14px 16px;margin-bottom:16px;color:var(--ink-soft);font-size:15.5px;
}
.scenario b{color:var(--ink)}
.question-text{font-size:20px;font-weight:700;margin:0 0 20px;line-height:1.5}

.options{display:flex;flex-direction:column;gap:11px}
.option{
  border:1.5px solid var(--line);border-radius:13px;padding:14px 16px;
  cursor:pointer;transition:.15s;display:flex;gap:12px;align-items:flex-start;
  font-size:16px;background:#fff;
}
.option:hover{border-color:var(--brand);background:var(--brand-soft)}
.option.selected{border-color:var(--brand);background:var(--brand-soft)}
.option.disabled{cursor:default;pointer-events:none}
.option .opt-letter{
  flex:0 0 28px;height:28px;border-radius:8px;background:#eef1f7;color:var(--ink-soft);
  display:grid;place-items:center;font-weight:700;font-size:14px;transition:.15s;
}
.option.selected .opt-letter{background:var(--brand);color:#fff}
.option.correct{border-color:var(--ok);background:var(--ok-soft)}
.option.correct .opt-letter{background:var(--ok);color:#fff}
.option.wrong{border-color:var(--bad);background:var(--bad-soft)}
.option.wrong .opt-letter{background:var(--bad);color:#fff}
.option .opt-text{flex:1;padding-top:2px}

/* ---------- feedback ---------- */
.feedback{margin-top:22px;animation:fade .3s ease}
.feedback-banner{font-weight:700;font-size:17px;padding:12px 16px;border-radius:12px;margin-bottom:14px}
.feedback-banner.ok{background:var(--ok-soft);color:var(--ok)}
.feedback-banner.bad{background:var(--bad-soft);color:var(--bad)}
.feedback-body{font-size:15.5px}
.fb-line{padding:10px 0;border-top:1px solid var(--line);display:flex;gap:9px}
.fb-line:first-child{border-top:none}
.fb-ic{flex:0 0 20px;font-weight:700}
.fb-ic.g{color:var(--ok)}
.fb-ic.r{color:var(--bad)}
.fb-line b{color:var(--ink)}
.fb-line span{color:var(--ink-soft)}

.quiz-nav{margin-top:20px;display:flex;justify-content:space-between;align-items:center;gap:12px}
.quiz-nav-main{display:flex}
.quiz-nav .btn-primary{min-width:200px}
.btn-finish{
  background:var(--bad-soft);color:var(--bad);border:1.5px solid #f1c4c3;
  border-radius:14px;padding:14px 26px;font-size:16px;font-weight:700;
  font-family:inherit;cursor:pointer;transition:.18s;white-space:nowrap;min-width:200px;
}
.btn-finish:hover{background:#f7dcdb;border-color:var(--bad);transform:translateY(-1px)}

/* ---------- results ---------- */
.results-card{text-align:center;padding:34px 26px}
.results-title{font-size:26px;margin:0 0 4px;font-weight:800}
.results-topic{color:var(--muted);margin:0 0 22px;font-weight:600}

.score-ring-wrap{position:relative;width:160px;height:160px;margin:0 auto 18px}
.score-ring{transform:rotate(-90deg);width:160px;height:160px}
.ring-bg{fill:none;stroke:#e4e9f2;stroke-width:11}
.ring-fill{fill:none;stroke:url(#g);stroke-width:11;stroke-linecap:round;
  stroke-dasharray:327;stroke-dashoffset:327;transition:stroke-dashoffset 1s ease;stroke:var(--brand)}
.score-center{position:absolute;inset:0;display:grid;place-items:center;flex-direction:column}
.score-percent{font-size:40px;font-weight:800;line-height:1}
.score-label{font-size:13px;color:var(--muted)}

.score-tally{display:flex;gap:14px;justify-content:center;margin:8px 0 26px}
.tally{border-radius:14px;padding:14px 26px;min-width:110px}
.tally span{display:block;font-size:30px;font-weight:800;line-height:1}
.tally small{font-size:13px;font-weight:600}
.tally-ok{background:var(--ok-soft)}
.tally-ok span{color:var(--ok)}
.tally-bad{background:var(--bad-soft)}
.tally-bad span{color:var(--bad)}

.analysis{display:grid;grid-template-columns:1fr 1fr;gap:16px;text-align:right;margin-bottom:26px}
.analysis-col{background:#f8fafd;border:1px solid var(--line);border-radius:14px;padding:16px}
.analysis-col h3{margin:0 0 10px;font-size:16px}
.an-strong{color:var(--ok)}
.an-weak{color:var(--warn)}
.an-list{margin:0;padding:0;list-style:none}
.an-list li{font-size:14px;padding:5px 0;color:var(--ink-soft);display:flex;justify-content:space-between;gap:8px}
.an-list li b{color:var(--ink);font-weight:600}
.an-list li .pct{font-weight:700;font-size:13px}
.an-empty{color:var(--muted);font-size:14px}

.mistakes-title{text-align:right;font-size:18px;margin:0 0 14px}
.mistakes-list{text-align:right;display:flex;flex-direction:column;gap:12px;margin-bottom:26px}
.mistake{border:1px solid var(--line);border-radius:13px;padding:15px 16px;background:#fff}
.mistake .mk-q{font-weight:600;margin-bottom:9px}
.mistake .mk-row{font-size:14.5px;display:flex;gap:8px;padding:3px 0}
.mistake .mk-row .mk-ic{flex:0 0 18px;font-weight:700}
.mistake .mk-bad{color:var(--bad)}
.mistake .mk-ok{color:var(--ok)}
.mistake .mk-expl{font-size:14px;color:var(--ink-soft);margin-top:8px;padding-top:8px;border-top:1px dashed var(--line)}
.mistakes-empty{text-align:center;color:var(--ok);font-weight:600;background:var(--ok-soft);padding:18px;border-radius:13px}

.results-actions{display:flex;gap:12px;justify-content:center;flex-wrap:wrap}

/* ---------- footer ---------- */
.site-footer{border-top:1px solid var(--line);background:var(--card);padding:18px 0;margin-top:20px}
.site-footer .wrap{text-align:center;color:var(--muted);font-size:13px}

/* ---------- mobile ---------- */
@media(max-width:600px){
  .hero h1{font-size:24px}
  .question-text{font-size:18px}
  .card{padding:20px 16px}
  .topics-grid{grid-template-columns:1fr}
  .analysis{grid-template-columns:1fr}
  .quiz-nav{flex-direction:column-reverse;align-items:stretch}
  .quiz-nav-main{flex-direction:column}
  .quiz-nav .btn-primary,.quiz-nav .btn-finish,.results-actions .btn-primary,.results-actions .btn-ghost{width:100%}
  .results-actions{flex-direction:column}
  .header-inner{height:auto;flex-wrap:wrap;gap:8px;padding:10px 0}
  .btn-ghost{padding:8px 11px;font-size:13px}
  .user-chip{padding:7px 11px;font-size:13px}
  .header-actions{gap:6px}
  .btn-finish{min-width:0}
  .login-row{flex-direction:column}
}