/* Header and navigation */
.site-header {
  position: sticky;
  top: 10px;
  z-index: 100;
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 28px;
  border: 1px solid;
  border-radius: var(--radius-lg);
  padding: 12px 14px;
  backdrop-filter: blur(18px);
  box-shadow: var(--shadow-soft);
}

.dark-mode .site-header {
  background: rgba(20, 25, 39, 0.86);
  border-color: rgba(255, 255, 255, 0.09);
}

.light-mode .site-header {
  background: rgba(255, 255, 255, 0.88);
  border-color: rgba(17, 24, 39, 0.08);
}

.brand {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 12px;
  min-width: 0;
  color: inherit;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 42px;
  height: 42px;
  flex: 0 0 42px;
  place-items: center;
  border-radius: 14px;
  background: linear-gradient(135deg, var(--accent), var(--purple));
  color: #fff;
  font-weight: 800;
  letter-spacing: -0.04em;
}

.brand-text {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.brand-title {
  font-size: clamp(1rem, 1.6vw, 1.22rem);
  font-weight: 800;
  letter-spacing: -0.035em;
  line-height: 1.1;
}

.brand-subtitle {
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  opacity: 0.64;
  text-transform: uppercase;
}

.header-controls {
  display: flex;
  flex: 1 1 auto;
  align-items: center;
  justify-content: flex-end;
  gap: 10px;
  min-width: 0;
}

.header-actions,
.section-nav,
.practice-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.header-actions,
.section-nav {
  flex-wrap: nowrap;
  min-width: 0;
}

.practice-actions {
  flex-wrap: wrap;
  justify-content: flex-end;
}

.section-nav a {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 36px;
  border: 1px solid rgba(99, 144, 241, 0.32);
  border-radius: 999px;
  padding: 7px 12px;
  background: rgba(99, 144, 241, 0.10);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.035);
  color: var(--accent-strong);
  font: inherit;
  font-size: 0.92rem;
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
  transition: transform 0.16s ease, background-color 0.16s ease, border-color 0.16s ease, color 0.16s ease;
}

.dark-mode .section-nav a {
  background: rgba(99, 144, 241, 0.12);
  color: #bcd0ff;
}

.light-mode .section-nav a {
  background: rgba(99, 144, 241, 0.11);
  color: var(--accent-deep);
}