:root {
  --bg: #0b1026;
  --bg2: #141a3a;
  --card: #1a2148;
  --card-border: #2c3670;
  --text: #eef1ff;
  --muted: #9aa3d0;
  --accent: #7c6cff;
  --accent2: #4dd0e1;
  --good: #34d399;
  --good-bg: #0f3d2e;
  --bad: #f87171;
  --bad-bg: #45191c;
  --gold: #fbbf24;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html, body { height: 100%; }

body {
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  background: radial-gradient(1200px 800px at 80% -10%, #26206b 0%, var(--bg) 55%) fixed, var(--bg);
  color: var(--text);
  line-height: 1.55;
  overflow-x: hidden;
}

/* símbolos flutuando ao fundo */
.bg-symbols { position: fixed; inset: 0; pointer-events: none; z-index: 0; overflow: hidden; }
.bg-symbols span {
  position: absolute;
  color: rgba(124, 108, 255, 0.10);
  font-size: 2.2rem;
  animation: floatUp linear infinite;
  user-select: none;
}
@keyframes floatUp {
  from { transform: translateY(105vh) rotate(0deg); }
  to   { transform: translateY(-10vh) rotate(30deg); }
}

#app { position: relative; z-index: 1; max-width: 760px; margin: 0 auto; padding: 24px 16px 60px; }

.screen { display: none; }
.screen.active { display: block; animation: fadeIn .35s ease; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }

/* ===== HOME ===== */
.hero { text-align: center; padding: 36px 0 28px; }
.atom { font-size: 3.6rem; animation: spinSlow 14s linear infinite; display: inline-block; }
@keyframes spinSlow { to { transform: rotate(360deg); } }
.hero h1 {
  font-size: 2.6rem; letter-spacing: -0.02em; margin-top: 6px;
  background: linear-gradient(90deg, var(--accent2), var(--accent));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.subtitle { color: var(--muted); font-weight: 600; margin-top: 2px; }
.tagline { color: var(--muted); font-style: italic; margin-top: 10px; }

.modes { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 14px; margin-top: 10px; }
.mode-card {
  background: var(--card); border: 1px solid var(--card-border); border-radius: 16px;
  padding: 18px 16px; color: var(--text); text-align: left; cursor: pointer;
  display: flex; flex-direction: column; gap: 4px;
  transition: transform .15s ease, border-color .15s ease, box-shadow .15s ease;
}
.mode-card:hover { transform: translateY(-3px); border-color: var(--accent); box-shadow: 0 8px 24px rgba(124,108,255,.25); }
.mode-emoji { font-size: 1.8rem; }
.mode-name { font-size: 1.15rem; font-weight: 700; }
.mode-desc { color: var(--muted); font-size: .9rem; }
.mode-count { color: var(--accent2); font-size: .82rem; font-weight: 600; margin-top: 4px; }
.mode-card.disabled { opacity: .55; cursor: default; }
.mode-card.disabled:hover { transform: none; border-color: var(--card-border); box-shadow: none; }

.best { text-align: center; color: var(--gold); margin-top: 22px; font-weight: 600; min-height: 1.4em; }

.materials { margin-top: 26px; }
.materials h3 { text-align: center; color: var(--muted); font-size: 1rem; margin-bottom: 12px; font-weight: 600; }
.mat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 10px; }
.mat-link {
  display: block; text-align: center; text-decoration: none;
  background: var(--bg2); color: var(--text); border: 1px solid var(--card-border);
  border-radius: 12px; padding: 12px 10px; font-size: .92rem; font-weight: 600;
  transition: border-color .12s ease, transform .12s ease;
}
.mat-link:hover { border-color: var(--accent2); transform: translateY(-2px); }

/* ===== QUIZ ===== */
.quiz-top { display: flex; align-items: center; gap: 12px; margin-bottom: 16px; }
.progress-wrap { flex: 1; display: flex; align-items: center; gap: 10px; }
.progress-bar { flex: 1; height: 10px; background: var(--card); border-radius: 99px; overflow: hidden; border: 1px solid var(--card-border); }
#progress-fill { height: 100%; width: 0%; background: linear-gradient(90deg, var(--accent2), var(--accent)); border-radius: 99px; transition: width .3s ease; }
#progress-text { color: var(--muted); font-size: .88rem; font-variant-numeric: tabular-nums; white-space: nowrap; }
.scorebox { display: flex; align-items: center; gap: 8px; }
.score { font-weight: 800; font-size: 1.15rem; color: var(--gold); font-variant-numeric: tabular-nums; }
.streak { font-weight: 700; color: #ff9e57; font-size: .95rem; }

.card {
  background: var(--card); border: 1px solid var(--card-border); border-radius: 18px;
  padding: 22px; box-shadow: 0 10px 30px rgba(0,0,0,.35);
}

.q-meta { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 14px; }
.chip {
  font-size: .75rem; font-weight: 700; letter-spacing: .02em;
  background: rgba(124,108,255,.15); color: #b7aeff; border: 1px solid rgba(124,108,255,.35);
  padding: 3px 10px; border-radius: 99px;
}
.chip-dif { background: rgba(77,208,225,.12); color: var(--accent2); border-color: rgba(77,208,225,.3); }
.chip-fonte { background: rgba(255,255,255,.06); color: var(--muted); border-color: rgba(255,255,255,.12); }

.q-text { font-size: 1.08rem; margin-bottom: 18px; }
.q-text .katex-display { margin: .6em 0; overflow-x: auto; overflow-y: hidden; padding: 2px 0; }

.options { display: grid; gap: 10px; }
.opt {
  display: flex; align-items: flex-start; gap: 12px; width: 100%; text-align: left;
  background: var(--bg2); color: var(--text); border: 1.5px solid var(--card-border);
  border-radius: 12px; padding: 12px 14px; font-size: 1rem; cursor: pointer;
  transition: border-color .12s ease, background .12s ease, transform .12s ease;
}
.opt:hover:not(:disabled) { border-color: var(--accent); transform: translateX(3px); }
.opt:disabled { cursor: default; }
.opt .letter {
  flex: 0 0 auto; width: 26px; height: 26px; border-radius: 8px; display: grid; place-items: center;
  background: rgba(124,108,255,.2); color: #b7aeff; font-weight: 800; font-size: .85rem;
}
.opt .katex-display { margin: .4em 0; overflow-x: auto; overflow-y: hidden; }
.opt-body { min-width: 0; overflow-x: auto; }

.opt.correct { border-color: var(--good); background: var(--good-bg); animation: pulseGood .4s ease; }
.opt.correct .letter { background: var(--good); color: #04150e; }
.opt.wrong { border-color: var(--bad); background: var(--bad-bg); animation: shake .35s ease; }
.opt.wrong .letter { background: var(--bad); color: #2a0708; }
.opt.dim { opacity: .5; }

@keyframes pulseGood { 0% { transform: scale(1); } 40% { transform: scale(1.02); } 100% { transform: scale(1); } }
@keyframes shake { 0%,100% { transform: translateX(0); } 25% { transform: translateX(-6px); } 75% { transform: translateX(6px); } }

.feedback { margin-top: 16px; border-top: 1px dashed var(--card-border); padding-top: 14px; }
.feedback.hidden { display: none; }
.feedback-title { font-weight: 800; font-size: 1.05rem; margin-bottom: 6px; }
.feedback-title.ok { color: var(--good); }
.feedback-title.nok { color: var(--bad); }
.feedback-text { color: #cdd3f5; font-size: .97rem; margin-bottom: 14px; }
.feedback-text .katex-display { overflow-x: auto; overflow-y: hidden; }

.btn-primary {
  background: linear-gradient(90deg, var(--accent), #9b6cff); color: #fff; border: 0;
  font-size: 1rem; font-weight: 700; padding: 11px 22px; border-radius: 12px; cursor: pointer;
  transition: transform .12s ease, box-shadow .12s ease;
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 6px 18px rgba(124,108,255,.4); }
.btn-ghost {
  background: transparent; color: var(--muted); border: 1px solid var(--card-border);
  padding: 8px 14px; border-radius: 10px; cursor: pointer; font-size: .95rem;
}
.btn-ghost:hover { color: var(--text); border-color: var(--accent); }

.kbd-hint { text-align: center; color: var(--muted); font-size: .8rem; margin-top: 14px; }
.kbd-hint b { color: var(--accent2); }

/* ===== FIM ===== */
.end-card { text-align: center; padding: 40px 24px; }
.end-emoji { font-size: 4rem; }
.end-card h2 { margin: 10px 0 4px; font-size: 1.6rem; }
.end-score { font-size: 3.2rem; font-weight: 800; color: var(--gold); margin: 8px 0; font-variant-numeric: tabular-nums; }
#end-detail { color: var(--muted); }
.end-actions { display: flex; gap: 12px; justify-content: center; margin-top: 24px; flex-wrap: wrap; }

#confetti { position: fixed; inset: 0; pointer-events: none; z-index: 50; }

@media (max-width: 520px) {
  .hero h1 { font-size: 2rem; }
  .card { padding: 16px; }
  .q-text { font-size: 1rem; }
  #progress-text { display: none; }
}