:root {
  --bg: #ffffff;
  --ink: #000000;
  --muted: #555555;
  --accent: #000000;
  --accent-ink: #ffffff;
  --right: #2a7a3b;
  --right-bg: #e8f5ec;
  --wrong: #b3261e;
  --wrong-bg: #fbeceb;
  --rule: #d0d0d0;
  --card: #ffffff;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  line-height: 1.5;
}

main {
  max-width: 1400px;
  margin: 0 auto;
  padding: 48px 32px 96px;
}

.screen { display: none; }
.screen.active { display: block; }

#title.active.welcome,
#consent.active.welcome {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - 144px);
  padding-top: 0;
}

.welcome {
  text-align: center;
  padding-top: 80px;
}
.welcome h1 { font-size: 128px; margin-bottom: 48px; letter-spacing: -1px; }
.welcome h2 { font-size: 96px; margin-bottom: 48px; }
.welcome .tagline { font-size: 36px; max-width: 900px; margin-left: auto; margin-right: auto; margin-bottom: 48px; }
.welcome > .primary { margin-top: 32px; padding: 32px 96px; font-size: 32px; height: auto; min-width: 320px; border-radius: 8px; }
#consent .consent-fine { font-size: 24px; max-width: 880px; margin-bottom: 56px; line-height: 1.6; }
#consent .consent-buttons { gap: 24px; }
#consent .consent-buttons .primary,
#consent .consent-buttons .secondary {
  height: 88px;
  min-width: 300px;
  font-size: 26px;
  padding: 0 48px;
  border-radius: 8px;
}

@media (min-width: 1200px) {
  .welcome h1 { font-size: 156px; }
  .welcome h2 { font-size: 112px; }
  .welcome .tagline { font-size: 40px; max-width: 1000px; }
  .welcome > .primary { padding: 36px 112px; font-size: 36px; min-width: 360px; }
  #consent .consent-fine { font-size: 26px; max-width: 960px; }
  #consent .consent-buttons .primary,
  #consent .consent-buttons .secondary {
    height: 96px;
    min-width: 340px;
    font-size: 28px;
  }
}

.consent-fine {
  max-width: 560px;
  margin: 0 auto 28px;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.6;
}
.consent-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}
.secondary {
  background: transparent;
  color: var(--ink);
  border: 2px solid var(--ink);
}
.secondary:hover { border-color: var(--ink); }

.video-placeholder {
  max-width: 720px;
  margin: 0 auto 32px;
  aspect-ratio: 16 / 9;
  background: #1d1b18;
  color: #faf8f4;
  border-radius: 14px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
}
.video-icon {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  background: rgba(255,255,255,0.12);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  padding-left: 6px;
}
.video-label { font-size: 18px; font-weight: 600; letter-spacing: 0.5px; }
.video-sub { font-size: 14px; color: rgba(250,248,244,0.6); }

/* ---------- title ---------- */
h1 {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 56px;
  line-height: 1.1;
  margin: 0 0 16px;
  letter-spacing: -0.5px;
}
h2 {
  font-family: Georgia, serif;
  font-size: 34px;
  margin: 0 0 24px;
}
.tagline {
  font-size: 20px;
  color: var(--muted);
  margin: 0 0 24px;
  max-width: 700px;
}
.how {
  font-size: 17px;
  padding-left: 20px;
  margin: 0 0 32px;
  max-width: 700px;
}
.how li { margin-bottom: 6px; }

.primary,
.secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 52px;
  padding: 0 28px;
  min-width: 180px;
  font-family: inherit;
  font-size: 17px;
  font-weight: 600;
  line-height: 1;
  border-radius: 4px;
  cursor: pointer;
  box-sizing: border-box;
}
.primary {
  background: var(--accent);
  color: var(--accent-ink);
  border: 2px solid var(--accent);
}
.primary:hover { opacity: 0.92; }
.primary:active { transform: translateY(1px); }

/* ---------- quiz ---------- */
.progress {
  height: 6px;
  background: var(--rule);
  border-radius: 4px;
  overflow: hidden;
  margin-bottom: 20px;
}
.progress-bar {
  height: 100%;
  width: 0;
  background: var(--accent);
  transition: width 0.3s ease;
}
.qheader {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 18px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 1.5px;
  margin-bottom: 16px;
}
.prompt {
  font-family: Georgia, serif;
  font-size: 44px;
  margin: 0 0 40px;
  text-align: center;
}

.pair-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
}

.pick-card {
  display: flex;
  flex-direction: column;
  text-align: left;
  background: var(--card);
  border: 2px solid var(--rule);
  border-radius: 18px;
  padding: 40px 36px;
  cursor: pointer;
  font: inherit;
  color: inherit;
  transition: border-color 0.12s ease, transform 0.05s ease, box-shadow 0.12s ease;
}
.pick-card:hover {
  border-color: var(--accent);
  box-shadow: 0 6px 18px rgba(90, 62, 200, 0.12);
}
.pick-card:active { transform: translateY(1px); }

.pick-label {
  font-size: 18px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 2px;
  font-weight: 700;
  margin-bottom: 20px;
}
.passage {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 26px;
  line-height: 1.6;
  white-space: pre-wrap;
  flex-grow: 1;
  margin-bottom: 28px;
}
.passage.poetry {
  font-style: italic;
  text-align: center;
}
.pick-cta {
  align-self: flex-start;
  background: var(--ink);
  color: var(--bg);
  padding: 16px 28px;
  border-radius: 6px;
  font-size: 20px;
  font-weight: 600;
}

@media (min-width: 1200px) {
  .prompt { font-size: 52px; }
  .passage { font-size: 30px; }
  .pick-cta { font-size: 22px; padding: 18px 32px; }
  .pick-label { font-size: 20px; }
}
.pick-card:hover .pick-cta {
  background: var(--accent);
}

/* ---------- results ---------- */
.breakdown {
  list-style: none;
  padding: 0;
  margin: 24px 0 32px;
}
.breakdown-item {
  border: 1px solid var(--rule);
  border-radius: 14px;
  padding: 22px 22px 18px;
  margin-bottom: 20px;
  background: #fff;
}
.breakdown-item.right { border-left: 5px solid var(--right); }
.breakdown-item.wrong { border-left: 5px solid var(--wrong); }

.breakdown-head {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
  font-size: 14px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 1px;
}
.mark { font-size: 22px; font-weight: 700; }
.right .mark { color: var(--right); }
.wrong .mark { color: var(--wrong); }
.qnum { font-weight: 700; color: var(--ink); }

.pair-side {
  border: 1px solid var(--rule);
  border-radius: 10px;
  padding: 16px 16px 14px;
  background: #fff;
}
.pair-side.is-ai { background: var(--wrong-bg); border-color: rgba(179, 38, 30, 0.25); }
.pair-side.is-human { background: var(--right-bg); border-color: rgba(42, 122, 59, 0.25); }
.pair-side.picked { outline: 3px solid var(--accent); outline-offset: 2px; }

.side-label {
  font-size: 13px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 1.5px;
  margin-bottom: 10px;
}
.side-label strong { color: var(--ink); letter-spacing: 1px; }
.side-text {
  font-family: Georgia, serif;
  font-size: 16px;
  line-height: 1.5;
  white-space: pre-wrap;
  margin-bottom: 10px;
}
.side-text.poetry { font-style: italic; text-align: center; }
.side-attr { font-size: 13px; color: var(--muted); font-style: italic; }

.breakdown-meta {
  margin-top: 14px;
  font-size: 15px;
}

/* ---------- mobile ---------- */
@media (max-width: 760px) {
  main { padding: 28px 16px 64px; }
  h1 { font-size: 38px; }
  h2 { font-size: 26px; }
  .prompt { font-size: 20px; }
  .pair-grid { grid-template-columns: 1fr; }
  .passage { font-size: 17px; }
}