:root {
  --bg: #f6f8ff;
  --panel: #ffffff;
  --ink: #1f2a44;
  --muted: #516083;
  --primary: #4c6ef5;
  --primary-2: #6d4cff;
  --accent: #2f9e44;
  --line: #dbe2fb;
  --danger: #ef4444;
  --shadow: 0 14px 35px rgba(53, 70, 120, 0.15);
  font-synthesis: none;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: 'M PLUS 1', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  color: var(--ink);
  background: radial-gradient(circle at 12% 8%, #e8edff, transparent 28%), radial-gradient(circle at 88% 18%, #e9f7f1, transparent 24%), var(--bg);
  min-height: 100vh;
}

.page {
  max-width: 1100px;
  margin: 24px auto 48px;
  padding: 0 20px 30px;
}

.hero {
  border: 1px solid var(--line);
  background: linear-gradient(130deg, #ffffff, #f4f6ff 40%, #eef4ff);
  border-radius: 18px;
  padding: 24px;
  box-shadow: var(--shadow);
}

.kicker {
  text-transform: uppercase;
  letter-spacing: 1px;
  font-size: 0.8rem;
  color: var(--muted);
  margin: 0;
  font-weight: 700;
}

h1, h2, h3 { font-family: 'Space Grotesk', 'Arial', sans-serif; color: #1b2650; }
h1 { margin-top: 8px; margin-bottom: 10px; font-size: clamp(1.8rem, 4vw, 2.35rem); }
h2 { margin-top: 0; }

.tabs {
  margin-top: 16px;
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 8px;
}

.tab-btn {
  border: 1px solid var(--line);
  background: #fff;
  color: #32406a;
  border-radius: 12px;
  padding: 12px 10px;
  font-family: 'Space Grotesk', sans-serif;
  font-size: 0.95rem;
  cursor: pointer;
}

.tab-btn.active, .tab-btn:hover {
  border-color: #b9c8ff;
  background: linear-gradient(130deg, #ecf0ff, #e7f7ff);
  color: #11224f;
}

.panel {
  margin-top: 16px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 18px;
  display: none;
}

.panel.active { display: block; }

.cards {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.card {
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 16px;
  background: #fcfdff;
  box-shadow: 0 8px 20px rgba(54, 77, 146, 0.08);
}

.card ul, .card ol {
  margin-left: 18px;
  padding-left: 2px;
}

.form-grid {
  display: grid;
  gap: 12px;
  grid-template-columns: 1fr 1fr;
  margin-top: 14px;
}

.form-grid.two-col { grid-template-columns: 1fr 1fr 160px; align-items: end; }

label { display: flex; flex-direction: column; gap: 6px; font-weight: 700; }
input, select, button {
  border: 1px solid #d7dff5;
  border-radius: 10px;
  padding: 10px 12px;
  font: inherit;
  outline: none;
}

input:focus, select:focus { border-color: #9ab0ff; box-shadow: 0 0 0 3px #dbe5ff; }

.primary {
  background: linear-gradient(130deg, var(--primary), var(--primary-2));
  border: none;
  color: #fff;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.12s ease;
}

.primary:hover { transform: translateY(-2px); }

.result-box {
  margin-top: 12px;
  background: #f7f9ff;
  border: 1px solid #d8e0fa;
  border-radius: 12px;
  padding: 14px;
}

.muted { color: var(--muted); }
.formula { font-size: 1.05rem; }

.inline-inputs { display: flex; gap: 8px; }
.inline-inputs input { flex: 1; }

.hint-box {
  margin-top: 12px;
  border-left: 4px solid #4f8cf2;
  background: #eef3ff;
  border-radius: 10px;
  padding: 12px;
}

.quiz-card {
  border: 1px dashed #c8d5ff;
  border-radius: 14px;
  padding: 12px;
  background: #fcfdff;
}

.choice-grid {
  margin-top: 8px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
}

.choice-btn {
  border: 1px solid #bfd0ff;
  padding: 10px;
  border-radius: 10px;
  background: #fff;
  font-weight: 700;
  cursor: pointer;
}

.choice-btn:hover { background: #eef5ff; }

.score-row { display: flex; justify-content: space-between; align-items: center; margin-top: 12px; gap: 10px; }

.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; margin-top: 10px; }
th, td { border-bottom: 1px solid #d8e0fa; padding: 10px; text-align: left; }
th { color: #3c4b7b; }

footer { margin-top: 16px; text-align: center; color: #52618e; font-size: 0.9rem; }

@media (max-width: 840px) {
  .cards,
  .tabs,
  .form-grid,
  .form-grid.two-col,
  .choice-grid { grid-template-columns: 1fr; }

  .score-row { flex-direction: column; align-items: stretch; }
}