/* ==========================================================================
   SUBJECT.CSS — Subject page overrides & additions

/* --------------------------------------------------------------------------
   1. SUBJECT HEADER (unchanged)
   -------------------------------------------------------------------------- */
.subject-hero {
  padding-block: var(--space-16);
  background-color: var(--color-bg-page);
  border-bottom: 1px solid var(--color-border);
}
.subject-hero__inner {
  max-width: 720px;
}
.subject-hero__label {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
  padding: var(--space-2) var(--space-4);
  background-color: var(--color-accent-primary-bg);
  border: 1px solid rgba(0, 229, 255, 0.2);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: var(--weight-semibold);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent-primary);
}
.subject-hero__dot {
  width: 6px;
  height: 6px;
  border-radius: var(--radius-full);
  background-color: var(--color-accent-primary);
}
.subject-hero__title {
  font-size: clamp(var(--text-3xl), 5vw, var(--text-5xl));
  font-weight: var(--weight-extrabold);
  line-height: var(--leading-tight);
  margin-bottom: var(--space-4);
  letter-spacing: -0.03em;
}
.subject-hero__code {
  color: var(--color-accent-primary);
  font-family: var(--font-mono);
  font-weight: var(--weight-medium);
  font-size: 0.75em;
  margin-left: var(--space-2);
}
.subject-hero__description {
  font-size: var(--text-base);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin-bottom: var(--space-6);
  max-width: none;
}
.subject-hero__meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-4);
  font-size: var(--text-sm);
}
.subject-meta-item {
  display: flex;
  align-items: baseline;
  gap: var(--space-1);
}
.subject-meta-item__value {
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
}
.subject-meta-item__label {
  color: var(--color-text-muted);
}
.subject-meta-divider {
  width: 1px;
  height: 16px;
  background-color: var(--color-border);
}
@media (max-width: 640px) {
  .subject-hero { padding-block: var(--space-12); }
  .subject-hero__meta { gap: var(--space-3); }
  .subject-meta-divider { display: none; }
}

/* --------------------------------------------------------------------------
   2. SUBJECT LAYOUT (sidebar + content grid)
   -------------------------------------------------------------------------- */
.subject-body {
  padding-block: var(--space-12);
  background-color: var(--color-bg-page);
}
.sidebar-toggle {
  display: none;
  align-items: center;
  gap: var(--space-2);
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-text-primary);
  cursor: pointer;
  width: 100%;
  margin-bottom: var(--space-6);
  transition: background-color var(--transition-fast);
}
.sidebar-toggle:hover {
  background-color: var(--color-bg-surface-alt);
}
@media (max-width: 1024px) {
  .sidebar-toggle { display: flex; }
}
.subject-layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: var(--space-8);
  align-items: start;
}
@media (max-width: 1024px) {
  .subject-layout { grid-template-columns: 1fr; }
}
.subject-sidebar {
  position: sticky;
  top: calc(var(--nav-height) + var(--space-8));
  max-height: calc(100vh - var(--nav-height) - var(--space-16));
  overflow-y: auto;
  padding-right: var(--space-2);
}
.sidebar-inner {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}
.sidebar-section__label {
  display: block;
  font-size: var(--text-xs);
  font-weight: var(--weight-semibold);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: var(--space-3);
}

/* ========== FORCED SIDEBAR STYLES – use !important ========== */
.sidebar-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-2) var(--space-3);
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-text-secondary) !important;   /* grey forced */
  text-decoration: none;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  gap: var(--space-2);
}
.sidebar-link:hover {
  background-color: var(--color-bg-surface-alt);
  color: var(--color-text-primary) !important;    /* white on hover */
}
.sidebar-link--active {
  background-color: var(--color-accent-primary-bg);
  color: var(--color-accent-primary) !important;   /* cyan for active */
  border-left: 2px solid var(--color-accent-primary);
}
/* Utility links (Revision Workflow, etc.) – grey forced */
.sidebar-link--utility {
  color: var(--color-text-secondary) !important;
  border-left: 2px solid transparent;
}
.sidebar-link--utility:hover {
  color: var(--color-text-primary) !important;
}
.sidebar-link--utility.sidebar-link--active {
  color: var(--color-accent-primary) !important;
  background-color: var(--color-accent-primary-bg);
}
/* Abbreviation tags – per‑module colours (no !important needed) */
.sidebar-link__tag {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-bold);
  padding: 0 0.25rem;
  border-radius: var(--radius-sm);
}
.sidebar-link__tag--pure {
  color: var(--color-accent-primary);
}
.sidebar-link__tag--mechanics {
  color: var(--color-accent-secondary);
}
.sidebar-link__tag--stats {
  color: var(--palette-amber);
}
.sidebar-link__tag--further {
  color: var(--color-accent-primary);
}
.sidebar-link__level {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  background-color: var(--color-bg-surface-alt);
  padding: 0.125rem 0.375rem;
  border-radius: var(--radius-sm);
}
.sidebar-divider {
  height: 1px;
  background-color: var(--color-border);
  margin: var(--space-2) 0;
}
.sidebar-link--utility svg {
  flex-shrink: 0;
  opacity: 0.7;
}

@media (max-width: 1024px) {
  .subject-sidebar {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    bottom: 0;
    z-index: var(--z-dropdown);
    background-color: var(--color-bg-page);
    backdrop-filter: blur(16px);
    padding: var(--space-6);
    transform: translateX(-100%);
    transition: transform var(--transition-base);
    max-height: none;
    overflow-y: auto;
    border-right: 1px solid var(--color-border);
  }
  .subject-sidebar.sidebar--open {
    transform: translateX(0);
  }
  .sidebar-inner {
    max-width: 280px;
  }
}

/* --------------------------------------------------------------------------
   3. TOPIC CARDS (per-module left border accent – keep multi-colour)
   -------------------------------------------------------------------------- */
.topic-card {
  background-color: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  margin-bottom: var(--space-8);
  overflow: hidden;
  transition: border-color var(--transition-base), box-shadow var(--transition-base);
}
.topic-card:hover {
  border-color: var(--color-border-light);
  box-shadow: var(--shadow-md);
}
.topic-card {
  position: relative;
}
.topic-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background-color: var(--accent-color, var(--color-border));
}
.topic-card--pure { --accent-color: var(--color-accent-primary); }
.topic-card--mechanics { --accent-color: var(--color-accent-secondary); }
.topic-card--stats { --accent-color: var(--palette-amber); }
.topic-card--further { --accent-color: var(--color-accent-primary); }

.topic-card__header {
  padding: var(--space-6) var(--space-6) 0 var(--space-6);
}
.topic-card__title-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-3);
}
.topic-module-tag {
  font-family: var(--font-mono);
  font-weight: var(--weight-bold);
  font-size: var(--text-sm);
  background-color: var(--color-bg-surface-alt);
  padding: 0.25rem 0.5rem;
  border-radius: var(--radius-sm);
}
.topic-module-tag--pure { color: var(--color-accent-primary); }
.topic-module-tag--mechanics { color: var(--color-accent-secondary); }
.topic-module-tag--stats { color: var(--palette-amber); }
.topic-module-tag--further { color: var(--color-accent-primary); }

.topic-card__title {
  font-size: var(--text-xl);
  font-weight: var(--weight-bold);
  margin: 0;
}
.as-badge, .a2-badge {
  font-size: var(--text-xs);
  background-color: var(--color-bg-surface-alt);
  padding: 0.25rem 0.5rem;
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
}
.topic-card__subtitle {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin-top: var(--space-2);
  margin-bottom: 0;
}
.topic-card__body {
  padding: var(--space-6);
}
.topic-section {
  margin-bottom: var(--space-8);
}
.topic-section:last-child {
  margin-bottom: 0;
}
.topic-section__title {
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  color: var(--color-text-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: var(--space-3);
  padding-bottom: 0;
  border-bottom: none;
}

/* Concept grid (if used) */
.concept-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: var(--space-3);
}
.concept-item {
  background-color: var(--color-bg-surface-alt);
  padding: var(--space-3);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
}
.concept-item__name {
  font-weight: var(--weight-semibold);
  color: var(--color-text-primary);
  display: block;
  margin-bottom: var(--space-1);
}
.concept-item__desc {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  line-height: var(--leading-snug);
}

/* Notes row */
.notes-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  align-items: center;
}
.notes-preview {
  flex: 2;
  min-width: 150px;
}
.notes-preview__placeholder {
  background: linear-gradient(135deg, var(--color-bg-surface-alt) 0%, var(--color-bg-surface) 100%);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-2);
}
.notes-preview__icon {
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: var(--weight-bold);
  color: var(--color-text-muted);
}
.notes-preview__label {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
}
.notes-actions {
  flex: 1;
}
.btn--sm svg {
  vertical-align: middle;
  margin-right: var(--space-1);
}

/* Mistakes and Tips list */
.mistakes-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}
.mistake-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
}
.mistake-item__icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  margin-top: 1px;
  background-color: rgba(239, 68, 68, 0.12);
  border-radius: var(--radius-full);
  color: var(--palette-red);
  font-weight: var(--weight-bold);
  font-size: var(--text-xs);
  flex-shrink: 0;
}
.mistake-item__icon--tip {
  background-color: var(--color-accent-primary-bg);
  color: var(--color-accent-primary);
}
.mistake-item__text {
  flex: 1;
  min-width: 0;
}

/* Resources grid inside topic cards */
.resources-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}
.resource-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-3) var(--space-4);
  background-color: var(--color-bg-surface-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: all var(--transition-fast);
}
.resource-card:hover {
  border-color: var(--color-border-light);
  background-color: var(--color-bg-surface);
}
.resource-card__type {
  font-size: var(--text-xs);
  font-weight: var(--weight-semibold);
  color: var(--color-accent-primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.resource-card__name {
  font-size: var(--text-sm);
  color: var(--color-text-primary);
  font-weight: var(--weight-medium);
}
.resource-card__arrow {
  color: var(--color-text-muted);
  font-size: var(--text-base);
}

/* Workflow steps (used inside revision-workflow-section) */
.workflow-steps {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}
.workflow-step {
  display: flex;
  gap: var(--space-4);
  align-items: flex-start;
}
.workflow-step__num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  background-color: var(--color-accent-primary-bg);
  color: var(--color-accent-primary);
  font-weight: var(--weight-bold);
  border-radius: var(--radius-full);
  flex-shrink: 0;
}
.workflow-step div {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
}
.workflow-step strong {
  color: var(--color-text-primary);
}

/* --------------------------------------------------------------------------
   4. TIPS & RESOURCES SECTION (legacy – kept for pages that still use it)
   -------------------------------------------------------------------------- */
.tips-section {
  padding-block: var(--space-16);
  background-color: var(--color-bg-surface);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}
.tips-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-8);
}
@media (max-width: 768px) {
  .tips-grid {
    grid-template-columns: 1fr;
    gap: var(--space-12);
  }
}
.tips-column__title {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-base);
  font-weight: var(--weight-semibold);
  color: var(--color-text-primary);
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--color-border);
}
.tip-card {
  background-color: var(--color-bg-page);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  margin-bottom: var(--space-3);
}
.tip-card__tag {
  font-size: var(--text-xs);
  font-family: var(--font-mono);
  color: var(--color-accent-primary);
  margin-bottom: var(--space-2);
  display: inline-block;
}
.tip-card__text {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin: 0;
}
.tip-card--add {
  border: 1px dashed var(--color-border);
  background: transparent;
  text-align: center;
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
}
.tip-card__add-icon {
  font-weight: var(--weight-bold);
  font-size: var(--text-base);
}
.rec-resource-card {
  display: block;
  background-color: var(--color-bg-page);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-3);
  text-decoration: none;
  transition: all var(--transition-fast);
}
.rec-resource-card:hover {
  border-color: var(--color-border-light);
  background-color: var(--color-bg-surface-alt);
}
.rec-resource-card__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-3) var(--space-4);
  gap: var(--space-3);
}
.rec-resource-card__name {
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  color: var(--color-text-primary);
  margin-bottom: var(--space-1);
}
.rec-resource-card__desc {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  line-height: var(--leading-snug);
}
.rec-resource-card__arrow {
  color: var(--color-text-muted);
  font-size: var(--text-base);
  flex-shrink: 0;
}
.rec-resource-card--placeholder {
  border-style: dashed;
  opacity: 0.7;
}

/* --------------------------------------------------------------------------
   5. RESPONSIVE FIXES & ADDITIONAL SPACING
   -------------------------------------------------------------------------- */
@media (max-width: 768px) {
  .topic-card__header {
    padding: var(--space-4) var(--space-4) 0 var(--space-4);
  }
  .topic-card__body {
    padding: var(--space-4);
  }
  .concept-grid {
    grid-template-columns: 1fr;
  }
  .notes-row {
    flex-direction: column;
    align-items: stretch;
  }
}

/* Spacing adjustments for section headers inside workflow and tips */
.revision-workflow-section .section-header,
.general-tips-section .section-header {
  margin-bottom: var(--space-8);
}
/* Force active link to cyan, overriding any hover or visited states */
.sidebar-link--active,
.sidebar-link--active:link,
.sidebar-link--active:visited,
.sidebar-link--active:hover {
  color: var(--color-accent-primary) !important;
  background-color: var(--color-accent-primary-bg) !important;
  border-left: 2px solid var(--color-accent-primary) !important;
}