/* ============================================================
   physics-y12-m8-theme.css — Physics Year 12 Module 8
   Subject: Physics | Year: 12 | Module: 8 (From the Universe to the Atom)
   Palette: Deep space indigo / violet / cosmic purple
   ============================================================ */

:root {
  --primary:       #7c3aed;
  --primary-mid:   #5b21b6;
  --primary-light: rgba(124, 58, 237, 0.12);

  --accent:        #06b6d4;
  --accent-dark:   #0e7490;
  --accent-light:  rgba(6, 182, 212, 0.12);

  --accent-bg:     rgba(255, 255, 255, 0.88);
  --surface:       rgba(255, 255, 255, 0.96);
  --surface-solid: #ffffff;

  --mesh-1: #ede9fe;
  --mesh-2: #e0f2fe;
  --mesh-3: #f5f3ff;
  --mesh-gradient: radial-gradient(ellipse at 20% 20%, var(--mesh-1) 0%, transparent 55%),
                   radial-gradient(ellipse at 80% 80%, var(--mesh-2) 0%, transparent 55%),
                   radial-gradient(ellipse at 50% 50%, var(--mesh-3) 0%, transparent 70%),
                   #fafaf9;

  --h2-color:      var(--heading-color);
  --shadow-accent: 0 4px 20px var(--primary-light);
}

body {
  background: radial-gradient(ellipse at 10% 20%, rgba(237,233,254,0.9) 0%, transparent 55%),
              radial-gradient(ellipse at 85% 10%, rgba(224,242,254,0.85) 0%, transparent 50%),
              radial-gradient(ellipse at 60% 80%, rgba(245,243,255,0.8) 0%, transparent 50%),
              linear-gradient(155deg, #f5f3ff 0%, #ede9fe 40%, #e0f2fe 75%, #fafaf9 100%);
  min-height: 100vh;
  font-size: 16px;
}

body { font-size: 16px !important; }
.page { max-width: 860px !important; }

h1, h2, h3, h4,
.hero h1,
.card h2,
.card h3,
.worked-example h4,
.section-label {
  font-family: 'Roboto Slab', 'Outfit', serif;
}

.hero h1 {
  font-size: 2rem;
  font-weight: 700;
  color: var(--heading-color);
  line-height: 1.2;
  margin: 12px 0 8px;
}

.hero .hero-desc {
  font-family: 'DM Sans', sans-serif;
  font-size: 1.05rem;
  opacity: 0.82;
  margin: 0 0 4px;
}

.hero-badge-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}

.hbadge-indigo {
  background: rgba(255,255,255,0.55);
  color: var(--text, #0f172a);
}

/* Interactive embed styling */
.interactive-embed {
  border: 2px solid var(--primary);
  border-radius: 16px;
  overflow: hidden;
  margin: 28px 0;
}
.interactive-label {
  background: var(--primary);
  color: white;
  padding: 8px 16px;
  font-weight: 700;
  font-size: 13px;
  font-family: 'DM Sans', sans-serif;
  letter-spacing: 0.3px;
}

/* Stop & Check prompt */
.stop-check {
  background: #f5f3ff;
  border-left: 4px solid var(--accent);
  border-radius: 0 12px 12px 0;
  padding: 18px 22px;
  margin: 20px 0;
}
.stop-check-label {
  font-size: 11px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--accent-dark);
  margin-bottom: 8px;
}
.stop-check p {
  margin: 0;
  font-size: 15px;
  color: #312e81;
  line-height: 1.6;
}

/* Formula panels */
.formula-panel {
  background: var(--surface-solid);
  border: 1px solid rgba(15,23,42,0.08);
  border-radius: 14px;
  padding: 18px 22px;
  margin: 20px 0;
}
.formula-panel-header {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 14px;
}
.formula-panel-icon {
  width: 32px; height: 32px;
  border-radius: 8px;
  background: var(--primary-light);
  display: flex; align-items: center; justify-content: center;
  font-size: 16px; color: var(--primary);
}
.formula-panel h3 {
  font-family: 'Roboto Slab', serif;
  font-size: 15px;
  font-weight: 700;
  color: var(--heading-color);
  margin: 0;
}
.formula-row {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 8px 0;
  border-bottom: 1px solid rgba(15,23,42,0.06);
}
.formula-row:last-child { border-bottom: none; }
.formula-eq {
  font-family: 'DM Mono', monospace;
  font-size: 15px;
  font-weight: 500;
  color: var(--primary-mid);
  white-space: nowrap;
}
.formula-var {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.45;
}

/* Activity cards */
.activity-card {
  background: #fafaf9;
  border: 2px solid #e7e5e4;
  border-radius: 14px;
  padding: 22px 26px;
  margin: 20px 0;
}
.activity-card-header {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}
.activity-badge {
  font-size: 10px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 1px;
  background: var(--primary);
  color: #fff;
  padding: 4px 10px;
  border-radius: 100px;
}
.activity-card h4 {
  font-family: 'Roboto Slab', serif;
  font-size: 16px;
  color: #0f172a;
  margin: 0;
}
.activity-card p {
  font-size: 14px;
  color: #475569;
  line-height: 1.65;
  margin: 0 0 12px;
}
.activity-card ol, .activity-card ul {
  margin: 8px 0 8px 18px;
  padding: 0;
  font-size: 14px;
  color: #475569;
  line-height: 1.7;
}

/* SVG diagrams */
.svg-diagram { margin: 20px 0; text-align: center; }
.svg-diagram svg {
  max-width: 100%; height: auto;
  display: block; margin: 0 auto;
}
.svg-caption {
  font-size: 12px;
  color: #64748b;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-top: 8px;
  opacity: 0.75;
}