@import url('https://fonts.googleapis.com/css2?family=Roboto+Mono:wght@400;500;700&display=swap');

:root {
  --green: #009b47;
  --green-dark: #007a38;
  --green-light: #e6f4ed;
  --green-mid: #c3e6d1;
  --mustard: #c8920a;
  --mustard-light: #fdf3dc;
  --mustard-mid: #f0d080;
  --navy: #0f1f14;
  --ink: #1a2e20;
  --ink-2: #3d5247;
  --ink-3: #6b7f73;
  --border: #d6e4db;
  --bg: #ffffff;
  --bg-2: #f7faf8;
  --bg-3: #f0f5f2;
  --offwhite: #f5f2ec;
  --red: #c0392b;
  --red-light: #fdf0ef;
  --font: 'Roboto Mono', monospace;
  --max: 1120px;
  --container-sm: 720px;
}

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--ink);
  line-height: 1.6;
}

a {
  color: var(--green);
  text-decoration: none;
}

a:hover {
  color: var(--green-dark);
}

.container {
  width: 100%;
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 32px;
}

.container--sm {
  max-width: var(--container-sm);
}

.site-nav {
  border-bottom: 2px solid var(--ink);
  background: var(--bg);
  position: sticky;
  top: 0;
  z-index: 100;
}

.site-nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.site-nav__logo {
  font-family: var(--font);
  font-weight: 700;
  font-size: 14px;
  letter-spacing: 0.04em;
  color: var(--ink);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 10px;
}

.site-nav__logo-tri {
  width: 0;
  height: 0;
  border-left: 7px solid transparent;
  border-right: 7px solid transparent;
  border-bottom: 12px solid var(--green);
  flex-shrink: 0;
}

.site-nav__logo span {
  color: var(--green);
}

.site-nav__links {
  display: flex;
  align-items: center;
  gap: 28px;
}

.site-nav__link {
  font-size: 12px;
  font-weight: 500;
  color: var(--ink-2);
  letter-spacing: 0.04em;
  transition: color 0.1s;
}

.site-nav__link:hover {
  color: var(--green);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--font);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 10px 20px;
  border: 2px solid transparent;
  cursor: pointer;
  transition: background 0.1s, color 0.1s, border-color 0.1s;
  text-decoration: none;
  white-space: nowrap;
}

.btn--primary {
  background: var(--green);
  color: #fff;
  border-color: var(--green);
}

.btn--primary:hover {
  background: var(--green-dark);
  border-color: var(--green-dark);
  color: #fff;
}

.btn--ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--border);
}

.btn--ghost:hover {
  border-color: var(--ink);
  color: var(--ink);
}

.btn--lg {
  font-size: 13px;
  padding: 13px 28px;
}

.badge--green {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 4px 10px;
  background: var(--green-light);
  color: var(--green-dark);
  border: 1px solid var(--green-mid);
}

.badge--green-tri {
  width: 0;
  height: 0;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-bottom: 7px solid var(--green);
  display: inline-block;
}

.hero {
  padding: 88px 0 72px;
  border-bottom: 1px solid var(--border);
}

.hero__eyebrow {
  margin-bottom: 24px;
}

.hero__title {
  font-size: clamp(32px, 5vw, 52px);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin-bottom: 20px;
}

.hero__title em {
  font-style: normal;
  color: var(--green);
  border-bottom: 3px solid var(--mustard);
  padding-bottom: 1px;
}

.hero__desc {
  font-size: 14px;
  color: var(--ink-2);
  max-width: 500px;
  line-height: 1.75;
  margin-bottom: 36px;
}

.hero__actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.stat-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  border: 1px solid var(--border);
  border-top: none;
}

.stat-card {
  padding: 28px 32px;
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.stat-card:last-child {
  border-right: none;
}

.stat-card__value {
  font-size: 36px;
  font-weight: 700;
  color: var(--green);
  line-height: 1;
  display: flex;
  align-items: center;
  gap: 10px;
}

.stat-card__tri {
  width: 0;
  height: 0;
  border-left: 5px solid transparent;
  border-right: 5px solid transparent;
  border-bottom: 9px solid var(--mustard);
  flex-shrink: 0;
}

.stat-card__label {
  font-size: 11px;
  color: var(--ink-3);
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.section {
  padding: 80px 0;
}

.divider {
  height: 1px;
  background: var(--border);
}

.section__label {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--mustard);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.section__label-tri {
  width: 0;
  height: 0;
  border-top: 5px solid transparent;
  border-bottom: 5px solid transparent;
  border-left: 8px solid var(--mustard);
  display: inline-block;
}

.section__title {
  font-size: clamp(22px, 3vw, 30px);
  font-weight: 700;
  color: var(--ink);
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 14px;
}

.section__desc {
  font-size: 13px;
  color: var(--ink-2);
  max-width: 500px;
  line-height: 1.75;
  margin-bottom: 40px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  border: 1px solid var(--border);
}

.feature-card {
  padding: 32px 28px;
  border-right: 1px solid var(--border);
  position: relative;
}

.feature-card:last-child {
  border-right: none;
}

.feature-card__corner {
  position: absolute;
  top: 0;
  right: 0;
  width: 0;
  height: 0;
  border-top: 16px solid var(--mustard-mid);
  border-left: 16px solid transparent;
}

.feature-card__icon {
  width: 32px;
  height: 32px;
  background: var(--offwhite);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
}

.feature-card__title {
  font-size: 13px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 8px;
  letter-spacing: 0.01em;
}

.feature-card__desc {
  font-size: 12px;
  color: var(--ink-2);
  line-height: 1.75;
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(190px, 1fr));
  border-top: 1px solid var(--border);
  border-left: 1px solid var(--border);
}

.topic-chip {
  padding: 16px 20px;
  font-size: 12px;
  font-weight: 500;
  color: var(--ink-2);
  border-right: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 8px;
  transition: background 0.1s, color 0.1s;
}

.topic-chip-tri {
  width: 0;
  height: 0;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-bottom: 6px solid var(--green-mid);
  flex-shrink: 0;
  display: inline-block;
  transition: border-bottom-color 0.1s;
}

.topic-chip:hover {
  background: var(--bg-2);
  color: var(--green);
}

.topic-chip:hover .topic-chip-tri {
  border-bottom-color: var(--green);
}

.cta-block {
  background: var(--navy);
  padding: 52px 48px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  flex-wrap: wrap;
  border-left: 4px solid var(--mustard);
}

.cta-block h2 {
  font-size: 24px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--offwhite);
  margin-bottom: 8px;
}

.cta-block p {
  font-size: 13px;
  color: rgba(255,255,255,0.5);
  max-width: 380px;
  line-height: 1.7;
}

.site-footer {
  border-top: 2px solid var(--ink);
  padding: 28px 0;
  background: var(--bg);
}

.site-footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
}

.site-footer__copy {
  font-size: 11px;
  color: var(--ink-3);
  letter-spacing: 0.04em;
}

.site-footer__links {
  display: flex;
  gap: 20px;
}

.site-footer__links a {
  font-size: 11px;
  color: var(--ink-3);
  letter-spacing: 0.04em;
  transition: color 0.1s;
}

.site-footer__links a:hover {
  color: var(--green);
}

.quiz-header {
  margin-bottom: 24px;
}

.quiz-header__top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
  flex-wrap: wrap;
  gap: 8px;
}

.pile-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.pile-chip {
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.05em;
  padding: 4px 10px;
  border: 1px solid;
  display: flex;
  align-items: center;
  gap: 6px;
  text-transform: uppercase;
}

.pile-chip--mastered {
  background: var(--green-light);
  border-color: var(--green-mid);
  color: var(--green-dark);
}

.pile-chip--mastered-tri {
  width: 0;
  height: 0;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-bottom: 6px solid var(--green);
  display: inline-block;
}

.pile-chip--review {
  background: var(--red-light);
  border-color: #f5c0bc;
  color: var(--red);
}

.pile-chip--review-tri {
  width: 0;
  height: 0;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-top: 6px solid var(--red);
  display: inline-block;
}

.pile-chip--unseen {
  background: var(--offwhite);
  border-color: var(--border);
  color: var(--ink-3);
}

.pile-chip--unseen-tri {
  width: 6px;
  height: 6px;
  border: 1px solid var(--ink-3);
  transform: rotate(45deg);
  display: inline-block;
  flex-shrink: 0;
}

.quiz-meta {
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.progress-track {
  height: 3px;
  background: var(--border);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--green);
  transition: width 0.3s;
}

.question-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-top: 3px solid var(--ink);
  padding: 36px;
}

.question-text {
  font-size: 15px;
  font-weight: 400;
  color: var(--ink);
  line-height: 1.65;
  margin-bottom: 28px;
}

.options-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.option-btn {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  width: 100%;
  padding: 14px 16px;
  background: var(--bg);
  border: 1px solid var(--border);
  cursor: pointer;
  text-align: left;
  font-family: var(--font);
  font-size: 13px;
  color: var(--ink-2);
  transition: border-color 0.1s, background 0.1s, color 0.1s;
  line-height: 1.5;
}

.option-btn:hover:not(:disabled) {
  border-color: var(--green);
  background: var(--green-light);
  color: var(--ink);
}

.option-btn:disabled {
  cursor: default;
}

.option-btn__key {
  flex-shrink: 0;
  width: 0;
  height: 0;
  border-left: 11px solid transparent;
  border-right: 11px solid transparent;
  border-bottom: 19px solid var(--bg-3);
  font-size: 0;
  color: transparent;
  position: relative;
  margin-top: 2px;
}

.option-btn__key-label {
  position: absolute;
  top: 5px;
  left: -5px;
  font-size: 9px;
  font-weight: 700;
  color: var(--ink-3);
  font-family: var(--font);
  width: 10px;
  text-align: center;
}

.option-btn--correct .option-btn__key {
  border-bottom-color: var(--green) !important;
}

.option-btn--correct .option-btn__key-label {
  color: #fff !important;
}

.option-btn--wrong .option-btn__key {
  border-bottom-color: var(--red) !important;
}

.option-btn--wrong .option-btn__key-label {
  color: #fff !important;
}

.option-btn--correct {
  background: var(--green-light) !important;
  border-color: var(--green) !important;
  color: var(--ink) !important;
}

.option-btn--wrong {
  background: var(--red-light) !important;
  border-color: var(--red) !important;
  color: var(--ink) !important;
}

.explanation-box {
  margin-top: 20px;
  padding: 18px 20px;
  font-size: 13px;
  line-height: 1.75;
  border-left: 3px solid;
}

.explanation-box--correct {
  background: var(--green-light);
  border-color: var(--green);
  color: var(--ink);
}

.explanation-box--wrong {
  background: var(--red-light);
  border-color: var(--red);
  color: var(--ink);
}

.next-row {
  margin-top: 16px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.kbd-hint {
  font-size: 10px;
  color: var(--ink-3);
  letter-spacing: 0.06em;
}

.kbd {
  display: inline-block;
  background: var(--bg-3);
  border: 1px solid var(--border);
  padding: 1px 5px;
  font-size: 9px;
  font-family: var(--font);
  margin: 0 1px;
}

.round-complete {
  text-align: center;
  padding: 72px 40px;
  border: 1px solid var(--border);
  border-top: 3px solid var(--ink);
  background: var(--bg);
}

.round-complete__icon {
  width: 0;
  height: 0;
  border-left: 24px solid transparent;
  border-right: 24px solid transparent;
  border-bottom: 42px solid var(--green);
  margin: 0 auto 28px;
}

.round-complete__title {
  font-size: 24px;
  font-weight: 700;
  color: var(--ink);
  letter-spacing: -0.02em;
  margin-bottom: 10px;
}

.round-complete__sub {
  font-size: 13px;
  color: var(--ink-2);
  margin-bottom: 32px;
  line-height: 1.7;
  max-width: 380px;
  margin-left: auto;
  margin-right: auto;
}

@media (max-width: 768px) {
  .container {
    padding: 0 20px;
  }

  .stat-row {
    grid-template-columns: 1fr 1fr;
  }

  .stat-row .stat-card:last-child {
    grid-column: 1 / -1;
  }

  .feature-grid {
    grid-template-columns: 1fr;
  }

  .feature-card {
    border-right: none;
    border-bottom: 1px solid var(--border);
  }

  .feature-card:last-child {
    border-bottom: none;
  }

  .section {
    padding: 56px 0;
  }

  .question-card {
    padding: 24px 20px;
  }

  .site-nav__link {
    display: none;
  }

  .cta-block {
    padding: 36px 28px;
  }
}