:root {
  color-scheme: dark;
  --bg: #0f172a;
  --panel: #1e293b;
  --text: #f1f5f9;
  --muted: #a7b5c5;
  --line: #475569;
  --green: #00b140;
  --green-dark: #007a33;
  --magenta: #d5008f;
  --correct-bg: #174b2d;
  --correct-text: #e1ffe9;
  --wrong-bg: #48282c;
  --wrong-text: #ffb1a8;
  --button: #334155;
  --button-hover: #475569;
  --shadow: 0 10px 30px rgba(0, 0, 0, .3);
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  color: var(--text);
  background: var(--bg);
}

* { box-sizing: border-box; }

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  padding: 24px 0;
  background: var(--bg);
  color: var(--text);
}

button { font: inherit; }
button:focus-visible, a:focus-visible, [tabindex="0"]:focus-visible {
  outline: 3px solid var(--magenta);
  outline-offset: 3px;
}

.page-shell {
  width: min(100% - 32px, 720px);
  margin-inline: auto;
}

.topbar {
  display: flex;
  min-height: 44px;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.wordmark {
  color: var(--text);
  font-size: 1.15rem;
  font-weight: 700;
  text-decoration: none;
}

.mode-label, .eyebrow {
  margin: 0;
  color: var(--green);
  font-size: .78rem;
  font-weight: 700;
}

.mode-label {
  padding: 6px 10px;
  border: 1px solid var(--green);
  border-radius: 999px;
}

.practice-panel {
  min-height: 360px;
  padding: 24px;
  border: 1px solid #334155;
  border-top: 4px solid var(--green);
  border-radius: 16px;
  background: var(--panel);
  box-shadow: var(--shadow);
}

.question-meta {
  display: flex;
  min-height: 26px;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.mastery { display: flex; gap: 5px; }
.mastery-dot {
  width: 12px;
  height: 12px;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: transparent;
}
.mastery-dot.filled { border-color: var(--green); background: var(--green); }

.question-prompt {
  margin: 20px 0;
  font-size: 1.3rem;
  line-height: 1.4;
}

.loading-message { padding: 48px 10px; color: var(--muted); text-align: center; }

.confidence {
  min-width: 0;
  margin: 0 0 18px;
  padding: 0;
  border: 0;
}
.confidence legend { margin-bottom: 9px; color: var(--muted); font-size: .9rem; }
.confidence-options { display: flex; gap: 8px; }
.confidence-button {
  width: 40px;
  height: 40px;
  border: 2px solid var(--line);
  border-radius: 50%;
  background: var(--button);
  color: var(--text);
  font-weight: 700;
  cursor: pointer;
}
.confidence-button:hover { border-color: var(--green); }
.confidence-button[aria-pressed="true"] { border-color: var(--green); background: var(--green); color: #052e16; }
.blind-mode-control {
  display: flex;
  align-items: center;
  gap: 9px;
  margin: 0 0 16px;
  color: var(--muted);
  font-size: .88rem;
}
.blind-mode-control input { width: 18px; height: 18px; margin: 0; accent-color: var(--green); }

.answer-options { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.answer-options.blinded { filter: blur(8px); opacity: .4; pointer-events: none; user-select: none; }
.answer-option {
  min-height: 56px;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--button);
  color: var(--text);
  text-align: left;
  line-height: 1.4;
  cursor: pointer;
}
.answer-option:hover:not(:disabled) { border-color: var(--green); background: var(--button-hover); }
.answer-option:disabled { cursor: default; }
.answer-option.is-correct { border-color: var(--green); background: var(--correct-bg); color: var(--correct-text); font-weight: 700; }
.answer-option.is-wrong { border-color: var(--magenta); background: var(--wrong-bg); color: var(--wrong-text); font-weight: 700; }

.answer-result { margin-top: 14px; }
.answer-feedback, .answer-explanation {
  margin: 0 0 10px;
  padding: 11px 13px;
  border-radius: 6px;
  line-height: 1.5;
}
.answer-feedback { border-left: 4px solid var(--green); background: var(--correct-bg); color: var(--correct-text); font-weight: 700; }
.answer-feedback.is-wrong { border-left-color: var(--magenta); background: var(--wrong-bg); color: var(--wrong-text); }
.answer-explanation { border-left: 3px solid var(--magenta); background: #29364a; color: var(--text); }

.pause-button, .reset-button {
  min-height: 42px;
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--button-hover);
  color: var(--text);
  font-weight: 700;
  cursor: pointer;
}
.pause-button:hover, .reset-button:hover { border-color: var(--green); }

.scoreboard { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; margin: 12px 0; }
.score-tile {
  display: flex;
  min-height: 62px;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 10px 12px;
  border: 1px solid #334155;
  border-radius: 8px;
  background: var(--panel);
}
.score-label { color: var(--muted); font-size: .84rem; }
.score-value { color: var(--green); font-size: 1.2rem; }

.page-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  color: var(--muted);
  font-size: .8rem;
  line-height: 1.5;
}
.page-footer p { max-width: 530px; margin: 8px 0; }
.reset-button { flex: 0 0 auto; }

.streak-reward {
  position: fixed;
  z-index: 20;
  top: 16px;
  left: 50%;
  width: min(100% - 32px, 430px);
  padding: 14px 18px;
  border: 2px solid #69e88b;
  border-radius: 8px;
  background: var(--green);
  color: #052e16;
  font-weight: 800;
  text-align: center;
  transform: translateX(-50%);
  animation: reward-pop .22s ease-out;
}
.confetti-layer { position: fixed; z-index: 19; inset: 0; overflow: hidden; pointer-events: none; }
.confetti-piece {
  position: absolute;
  top: -14px;
  width: 8px;
  height: 12px;
  border-radius: 2px;
  animation: confetti-fall 1.8s ease-in forwards;
}
@keyframes confetti-fall {
  to { transform: translateY(105vh) rotate(720deg); opacity: 0; }
}
@keyframes reward-pop {
  from { opacity: 0; translate: 0 -8px; }
  to { opacity: 1; translate: 0 0; }
}

.welcome-modal {
  width: min(100% - 32px, 520px);
  max-width: 520px;
  max-height: 90vh;
  padding: 28px;
  overflow: auto;
  border: 1px solid var(--line);
  border-top: 4px solid var(--green);
  border-radius: 16px;
  background: var(--panel);
  color: var(--text);
  box-shadow: var(--shadow);
}
.welcome-modal::backdrop { background: rgba(5, 10, 22, .82); }
.modal-mark {
  display: grid;
  width: 42px;
  aspect-ratio: 1;
  place-items: center;
  margin-bottom: 16px;
  border-radius: 50%;
  background: var(--green);
  color: #052e16;
  font-weight: 800;
}
.welcome-modal h1 { margin: 8px 0 10px; font-size: 1.65rem; line-height: 1.25; }
.welcome-modal > p:not(.eyebrow) { margin: 0; color: var(--muted); line-height: 1.6; }
.mode-choices { display: grid; gap: 9px; margin-top: 22px; }
.mode-choice {
  display: flex;
  min-height: 52px;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 14px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--button);
  color: var(--muted);
  font-size: 1rem;
  font-weight: 700;
  text-align: left;
}
.mode-choice span { font-size: .78rem; font-weight: 400; }
.mode-choice-primary { border-color: var(--green); background: var(--green); color: #052e16; cursor: pointer; }
.mode-choice-primary:hover { background: #00c34a; }
.mode-choice:disabled { cursor: not-allowed; opacity: .58; }
.coming-soon-wrap { position: relative; display: block; }
.coming-soon-wrap .mode-choice { width: 100%; }
.tooltip {
  position: absolute;
  z-index: 1;
  right: 12px;
  bottom: calc(100% + 6px);
  padding: 6px 9px;
  border-radius: 4px;
  background: #080d18;
  color: #fff;
  font-size: .75rem;
  opacity: 0;
  pointer-events: none;
}
.coming-soon-wrap:hover .tooltip, .coming-soon-wrap:focus .tooltip { opacity: 1; }

[hidden] { display: none !important; }

@media (max-width: 580px) {
  body { padding: 12px 0 24px; }
  .page-shell { width: min(100% - 24px, 720px); }
  .practice-panel { min-height: 0; padding: 19px 16px; }
  .answer-options { grid-template-columns: 1fr; }
  .scoreboard { gap: 6px; }
  .score-tile { min-height: 58px; flex-direction: column; justify-content: center; gap: 2px; padding: 7px 4px; text-align: center; }
  .score-label { font-size: .74rem; }
  .page-footer { align-items: flex-start; flex-direction: column; gap: 8px; }
  .confidence-options { justify-content: space-between; }
}

@media (prefers-color-scheme: light) {
  :root {
    color-scheme: light;
    --bg: #f7f7f9;
    --panel: #fff;
    --text: #172a3a;
    --muted: #526576;
    --line: #c9d4d8;
    --correct-bg: #e2f5e9;
    --correct-text: #075326;
    --wrong-bg: #fff0ee;
    --wrong-text: #8c241b;
    --button: #f1f4f6;
    --button-hover: #e3eaee;
    --shadow: 0 10px 30px rgba(13, 39, 54, .12);
  }
  .answer-explanation { background: #f7eaf3; }
  .mode-choice-primary { color: #052e16; }
  .welcome-modal::backdrop { background: rgba(15, 23, 42, .65); }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; }
  .confetti-layer { display: none; }
}