:root {
  --bg: #f6f4fb;
  --bg-sheen: #ffffff;
  --card-bg: #ffffff;
  --text: #1a1726;
  --muted: #6b6478;
  --accent: #7c3aed;
  --accent-2: #06b6d4;
  --accent-contrast: #ffffff;
  --border: #e8e3f5;
  --danger: #e0393a;
  --danger-bg: #fdeaea;
  --success: #0e9f6e;
  --success-bg: #e4f8f0;
  --warning: #c2790a;
  --shadow-sm: 0 1px 2px rgba(26, 23, 38, 0.06), 0 1px 3px rgba(26, 23, 38, 0.08);
  --shadow-md: 0 4px 10px rgba(26, 23, 38, 0.08), 0 2px 4px rgba(26, 23, 38, 0.06);
  --gradient: linear-gradient(135deg, var(--accent) 0%, var(--accent-2) 100%);
  color-scheme: light;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

body {
  max-width: 480px;
  margin: 0 auto;
  padding-inline: 16px;
  padding-bottom: calc(2rem + env(safe-area-inset-bottom, 0px));
  min-height: 100vh;
}

.topbar {
  position: sticky;
  top: env(safe-area-inset-top, 0px);
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding-block: 12px;
  border-bottom: 1px solid var(--border);
  z-index: 10;
}

.topbar h1 {
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin: 0;
  flex: 1;
  text-align: center;
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.iconbtn, .langbtn {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 8px 12px;
  font-size: 0.95rem;
  color: var(--text);
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: transform 0.12s ease, box-shadow 0.12s ease;
}
.iconbtn:active, .langbtn:active { transform: scale(0.94); }

.iconbtn { font-size: 1.1rem; padding: 6px 10px; }

.langbtn { font-weight: 700; min-width: 44px; color: var(--accent); }

main { padding-block: 16px; }

/* ---------- hero (home screen) ---------- */

.hero {
  position: relative;
  border-radius: 20px;
  padding: 22px 18px;
  margin-bottom: 16px;
  background:
    radial-gradient(circle at 15% 20%, rgba(255, 255, 255, 0.22), transparent 55%),
    var(--gradient);
  color: #ffffff;
  box-shadow: var(--shadow-md);
  overflow: hidden;
}
.hero-eyebrow {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: rgba(255, 255, 255, 0.2);
  padding: 3px 10px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.hero h2 { margin: 0 0 6px; font-size: 1.25rem; font-weight: 800; letter-spacing: -0.01em; }
.hero p { margin: 0; font-size: 0.9rem; opacity: 0.92; }

/* ---------- cards ---------- */

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 14px;
  margin-bottom: 12px;
  box-shadow: var(--shadow-sm);
}

.unit-card {
  display: block;
  width: 100%;
  text-align: left;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 14px;
  margin-bottom: 12px;
  cursor: pointer;
  font: inherit;
  color: inherit;
  box-shadow: var(--shadow-sm);
  transition: transform 0.12s ease, box-shadow 0.12s ease, border-color 0.12s ease;
}

.unit-card:active { transform: scale(0.98); box-shadow: var(--shadow-sm); }

.unit-card-row { display: flex; align-items: flex-start; gap: 12px; }
.unit-card-text { flex: 1; min-width: 0; }

.step-badge {
  flex: none;
  width: 32px;
  height: 32px;
  border-radius: 10px;
  background: var(--gradient);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 0.95rem;
  box-shadow: var(--shadow-sm);
}

.unit-card h3 { margin: 0 0 4px; font-size: 1.02rem; font-weight: 700; letter-spacing: -0.005em; }

.unit-meta { color: var(--muted); font-size: 0.85rem; margin: 0 0 8px; }

.info-card h3::before { content: "\2192  "; color: var(--accent); }

/* ---------- pace picker (top of home screen) ---------- */

.pace-top {
  border: 1px solid transparent;
  background:
    linear-gradient(var(--card-bg), var(--card-bg)) padding-box,
    var(--gradient) border-box;
  border-radius: 14px;
  padding: 14px;
  margin-bottom: 16px;
  box-shadow: var(--shadow-md);
}
.pace-top-label {
  margin: 0 0 2px;
  font-weight: 800;
  font-size: 1rem;
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.free-banner-line { margin: 0 0 10px; font-size: 0.78rem; font-weight: 600; color: var(--success); }
.pace-row { display: flex; flex-direction: column; gap: 8px; margin-bottom: 4px; }
.pace-card {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 2px;
  width: 100%;
  text-align: left;
  background: var(--card-bg);
  border: 1.5px solid var(--border);
  border-radius: 10px;
  padding: 10px 13px;
  cursor: pointer;
  font: inherit;
  color: var(--text);
  transition: border-color 0.12s ease, background 0.12s ease;
}
.pace-card strong { font-size: 0.95rem; }
.pace-card-row { display: flex; align-items: baseline; justify-content: space-between; width: 100%; gap: 8px; }
.pace-card-price { font-size: 0.85rem; white-space: nowrap; }
.pace-card-price .price-was { text-decoration: line-through; color: var(--muted); font-weight: 500; margin-right: 5px; }
.pace-card-price .price-free { color: var(--success); font-weight: 800; }
.pace-card-desc { font-size: 0.82rem; color: var(--muted); }
.pace-card.selected { border-color: var(--accent); border-width: 2px; background: #f1edfb; }
.pace-card.selected strong::after { content: "  \2713"; color: var(--accent); }

.small-note { font-size: 0.85rem; color: var(--muted); font-weight: 400 !important; }

.text-input {
  display: block;
  width: 100%;
  padding: 11px 13px;
  margin-bottom: 10px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--card-bg);
  color: var(--text);
  font: inherit;
}
.text-input:focus { outline: 2px solid var(--accent); outline-offset: 1px; }

.badge {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 999px;
  background: #f1edfb;
  color: var(--muted);
}

.badge.done { background: var(--success-bg); color: var(--success); }
.badge.pass { background: var(--success-bg); color: var(--success); }
.badge.pass::before { content: "\2713 "; }
.badge.fail { background: var(--danger-bg); color: var(--danger); }

/* ---------- buttons ---------- */

.btn {
  display: inline-block;
  background: var(--gradient);
  color: var(--accent-contrast);
  border: none;
  border-radius: 12px;
  padding: 13px 16px;
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: -0.005em;
  cursor: pointer;
  width: 100%;
  margin-top: 10px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.12s ease, box-shadow 0.12s ease;
}
.btn:active { transform: scale(0.97); }

.btn.secondary {
  background: var(--card-bg);
  color: var(--text);
  border: 1px solid var(--border);
  box-shadow: none;
}

.btn-row { display: flex; gap: 8px; margin-top: 10px; }
.btn-row .btn { margin-top: 0; }

.screen-block :is(h1,h2,h3,h4) { margin-top: 0; letter-spacing: -0.01em; }
.screen-block h2, .screen-block h3 { color: var(--accent); }
.screen-block p { margin: 0 0 10px; }
.screen-block ul, .screen-block ol { margin: 0 0 10px; padding-left: 1.2rem; }
.screen-block blockquote {
  margin: 0 0 10px;
  padding: 10px 12px;
  border-left: 3px solid var(--accent);
  background: #f1edfb;
  border-radius: 0 10px 10px 0;
  font-size: 0.95rem;
}
.screen-block table { border-collapse: collapse; width: 100%; font-size: 0.9rem; margin-bottom: 10px; }
.screen-block th { background: #f1edfb; }
.screen-block th, .screen-block td { border: 1px solid var(--border); padding: 6px 8px; text-align: left; }
.screen-block hr { border: none; border-top: 1px solid var(--border); margin: 10px 0; }

.progress-line { font-size: 0.8rem; font-weight: 600; color: var(--muted); margin-bottom: 10px; text-align: center; text-transform: uppercase; letter-spacing: 0.04em; }

.quiz-q { margin-bottom: 16px; }
.quiz-q p.question { font-weight: 700; margin-bottom: 8px; }
.option {
  display: block;
  width: 100%;
  text-align: left;
  background: var(--card-bg);
  border: 1.5px solid var(--border);
  border-radius: 10px;
  padding: 11px 13px;
  margin-bottom: 8px;
  cursor: pointer;
  font: inherit;
  color: inherit;
  transition: border-color 0.12s ease, background 0.12s ease;
}
.option.selected { border-color: var(--accent); background: #f1edfb; }
.option.correct { border-color: var(--success); background: var(--success-bg); }
.option.correct::after { content: "  \2713"; color: var(--success); font-weight: 800; }
.option.incorrect { border-color: var(--danger); background: var(--danger-bg); }
.option.incorrect::after { content: "  \2715"; color: var(--danger); font-weight: 800; }
.option[disabled] { cursor: default; }

.explanation {
  font-size: 0.88rem;
  color: var(--muted);
  background: #f1edfb;
  border-radius: 10px;
  padding: 9px 11px;
  margin-top: 4px;
}

.result-banner {
  text-align: center;
  padding: 16px;
  border-radius: 14px;
  margin-bottom: 14px;
  font-weight: 800;
  font-size: 1.05rem;
  box-shadow: var(--shadow-sm);
}
.result-banner.pass { background: var(--success-bg); color: var(--success); }
.result-banner.fail { background: var(--danger-bg); color: var(--danger); }

.footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.78rem;
  padding-block: 10px;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #130f1c;
    --bg-sheen: #1c1730;
    --card-bg: #1c1730;
    --text: #f0ecf9;
    --muted: #a79fc0;
    --accent: #a780fb;
    --accent-2: #38d6ef;
    --accent-contrast: #140b24;
    --border: #312a47;
    --danger: #ff8784;
    --danger-bg: #2c1c20;
    --success: #3fd99b;
    --success-bg: #163229;
    --warning: #ecb866;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 6px 16px rgba(0, 0, 0, 0.4);
  }
  :root:not([data-theme="light"]) .topbar h1 { -webkit-background-clip: text; background-clip: text; }
  :root:not([data-theme="light"]) .badge { background: #241c38; }
  :root:not([data-theme="light"]) .screen-block blockquote,
  :root:not([data-theme="light"]) .screen-block th,
  :root:not([data-theme="light"]) .option.selected,
  :root:not([data-theme="light"]) .pace-card.selected,
  :root:not([data-theme="light"]) .explanation { background: #241c38; }
  :root:not([data-theme="light"]) .hero { box-shadow: var(--shadow-md); }
}

[hidden] { display: none !important; }