/* ============================================================
   DESIGN TOKENS & PURE WHITE THEME
   ============================================================ */
:root {
  --paper:        #FFFFFF;
  --paper-line:   #E2E8F0;
  --ink:          #0F172A;
  --ink-soft:     #475569;
  --ink-muted:    #94A3B8;
  --card:         #FFFFFF;
  --card-border:  #CBD5E1;

  /* Connection Tier Colors */
  --strong:       #d97706;   /* amber/brass */
  --strong-soft:  #fef3c7;
  --related:      #0d9488;   /* teal */
  --related-soft: #ccfbf1;
  --weak:         #7c3aed;   /* violet */
  --weak-soft:    #ede9fe;
  --collapsed:    #64748b;

  --primary-accent: #2563eb;
  --primary-hover:  #1d4ed8;

  --font-display: 'Source Serif 4', Georgia, serif;
  --font-mono:    'IBM Plex Mono', ui-monospace, monospace;
  --font-body:    'Inter', system-ui, sans-serif;

  --radius:       4px;
  --radius-lg:    10px;
  --header-h:     84px;
  --footer-h:     52px;
  --drawer-w:     360px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html, body {
  height: 100%;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  overflow: hidden;
}

/* Crisp White Graph-Paper Grid Background */
body {
  background-color: #ffffff;
  background-image:
    linear-gradient(var(--paper-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--paper-line) 1px, transparent 1px);
  background-size: 28px 28px;
  background-attachment: fixed;
  display: flex;
  flex-direction: column;
}

button { font-family: inherit; cursor: pointer; }

/* ============================================================
   HEADER BAR
   ============================================================ */
.app-header {
  height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 28px;
  border-bottom: 1px solid var(--card-border);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 20;
}

.app-title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.5rem;
  margin: 0;
  letter-spacing: 0.01em;
}

.app-subtitle {
  margin: 2px 0 0;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink-soft);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 22px;
}

/* Connection Toggles */
#tierToggles, .tier-toggles {
  display: flex;
  align-items: center;
  gap: 10px;
}

.tier-toggle {
  display: flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 5px 9px;
  border-radius: var(--radius);
  border: 1px solid var(--card-border);
  background: var(--card);
  color: var(--ink-soft);
  user-select: none;
  cursor: pointer;
  font-weight: 600;
}

.tier-toggle input { accent-color: currentColor; }
.tier-toggle.tier-strong, .tier-toggle[data-tier="strong"] { color: var(--strong); border-color: var(--strong); }
.tier-toggle.tier-related, .tier-toggle[data-tier="related"] { color: var(--related); border-color: var(--related); }
.tier-toggle.tier-weak, .tier-toggle[data-tier="weak"] { color: var(--weak); border-color: var(--weak); }
.tier-toggle.is-off { opacity: 0.35; }

.mode-toggle { 
  display: flex; 
  border: 1px solid var(--card-border); 
  border-radius: var(--radius); 
  overflow: hidden; 
}

.mode-btn {
  border: none;
  background: var(--card);
  color: var(--ink-soft);
  font-size: 0.72rem;
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 8px 12px;
}

.mode-btn.is-active { background: var(--ink); color: var(--paper); }

/* Buttons */
.toolbar-actions { display: flex; align-items: center; gap: 8px; }

.btn {
  padding: 8px 16px;
  border-radius: var(--radius);
  border: 1px solid var(--card-border);
  background: #ffffff;
  color: var(--ink);
  cursor: pointer;
  font-weight: 600;
  font-size: 0.825rem;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: all 0.15s ease;
}

.btn:hover { background: #f1f5f9; }
.btn-primary { background: var(--primary-accent); color: #ffffff; border-color: var(--primary-accent); }
.btn-primary:hover { background: var(--primary-hover); }
.btn-secondary { background: #ffffff; color: var(--ink); border: 1px solid var(--card-border); }
.btn-cancel { background: transparent; color: var(--ink-soft); border: none; }
.btn-sm { padding: 4px 8px; font-size: 0.75rem; }

/* Custom Add Course Button */
.btn-add-course {
  background: #ffffff;
  color: #000000;
  border: 1px solid rgba(6, 6, 6, 0.4);
  padding: 8px 16px;
  border-radius: 6px;
  font-weight: 600;
  font-size: 13px;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.15);
}

.btn-add-course:hover {
  background: #ffffff;
  color: #0a192f;
  box-shadow: 0 0 4px rgba(0, 0, 0, 0.4);
}

/* ============================================================
   BOARD & CANVASES
   ============================================================ */
.board-wrap {
  position: relative;
  width: calc(100vw - var(--drawer-w));
  height: calc(100vh - var(--header-h) - var(--footer-h));
  overflow: auto;
  box-sizing: border-box;
}

/* SVG Connection Overlay */
.connection-layer, svg.connection-layer {
  position: absolute;
  top: 0; left: 0; width: 100%; height: 100%;
  pointer-events: none;
  z-index: 5;
  overflow: visible;
}

.connection-layer line, .connection-layer path {
  stroke-linecap: round;
  transition: stroke 0.15s ease, opacity 0.15s ease;
  filter: drop-shadow(0px 1px 1px rgba(0,0,0,0.08));
  fill: none;
}

.connection-layer line.strong, .connection-layer path.strong,
.connection-layer path[data-tier="strong"] {
  stroke: var(--strong) !important;
  stroke-width: 3px !important;
}

.connection-layer line.related, .connection-layer path.related,
.connection-layer path[data-tier="related"] {
  stroke: var(--related) !important;
  stroke-width: 2.5px !important;
  stroke-dasharray: 6 4 !important;
}

.connection-layer line.weak, .connection-layer path.weak,
.connection-layer path[data-tier="weak"] {
  stroke: var(--weak) !important;
  stroke-width: 2.5px !important;
  stroke-dasharray: 2 4 !important;
}

marker[id*="strong"] path { fill: var(--strong) !important; }
marker[id*="related"] path { fill: var(--related) !important; }
marker[id*="weak"] path { fill: var(--weak) !important; }

/* ============================================================
   YEAR BOXES
   ============================================================ */
.board {
  position: relative;
  z-index: 6;
  display: flex;
  align-items: flex-start;
  gap: 32px;
  padding: 32px 80px 100px 40px;
  width: max-content;
  min-width: 100%;
}

.year-box {
  display: flex;
  flex-direction: column;
  background: rgba(255, 255, 255, 0.9);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  min-width: 480px;
  align-self: flex-start;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
}

.year-box-header {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--ink);
  padding: 12px 18px;
  border-bottom: 2px solid var(--ink);
  background: #ffffff;
  border-top-left-radius: var(--radius-lg);
  border-top-right-radius: var(--radius-lg);
}

.year-canvas {
  position: relative;
  min-width: 480px;
  min-height: 550px;
  overflow: visible;
  display: block;
}

/* ============================================================
   COURSE CARDS & MODULE CHIPS
   ============================================================ */
.course-card {
  position: absolute;
  width: 230px;
  background: #ffffff;
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 12px;
  touch-action: none;
  user-select: none;
  z-index: 2;
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.05);
}

.course-card.is-dragging {
  z-index: 10;
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.16);
  cursor: grabbing;
}

.course-card-head {
  margin-bottom: 10px;
  cursor: grab;
}

.head-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 4px;
}

.drag-handle {
  cursor: grab;
  color: var(--ink-soft);
  font-size: 0.9rem;
  user-select: none;
  margin-right: 6px;
}

.course-code {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 600;
  color: var(--ink-soft);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  flex: 1;
}

.card-actions {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: auto;
}

/* Restored Action Icons (Gear, Calendar, Collapse, Delete) */
.edit-course-btn, .btn-calendar, .btn-delete-course, .collapse-btn {
  background: transparent;
  border: none;
  color: var(--ink-soft);
  font-size: 0.9rem;
  cursor: pointer;
  padding: 2px 4px;
  border-radius: 3px;
  line-height: 1;
  transition: color 0.15s ease, background 0.15s ease, transform 0.15s ease;
}

.edit-course-btn:hover {
  color: var(--primary-accent);
  background: #f1f5f9;
  transform: rotate(30deg);
}

.btn-calendar:hover, .collapse-btn:hover {
  background: var(--paper-line);
  color: var(--ink);
}

.btn-delete-course:hover {
  color: #ef4444;
}

.course-name {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
  margin: 2px 0 0;
  line-height: 1.25;
}

.module-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.course-card.is-collapsed .module-list { display: none; }
.course-card.is-collapsed { padding-bottom: 12px; }

.module-chip {
  display: block;
  width: 100%;
  text-align: left;
  background: #f8fafc;
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 7px 9px;
  font-size: 0.78rem;
  line-height: 1.25;
  color: var(--ink);
  transition: border-color .12s ease, background .12s ease;
}

.module-chip .m-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.63rem;
  font-weight: 600;
  color: var(--ink-soft);
  text-transform: uppercase;
  margin-bottom: 2px;
}

.module-chip:hover { border-color: var(--ink); }

/* Drag and Drop Visuals */
.module-chip.is-dragging-chip { opacity: 0.4; transform: scale(0.98); }
.module-chip.drag-over-top { border-top: 3px solid var(--primary-accent); }
.module-chip.drag-over-bottom { border-bottom: 3px solid var(--primary-accent); }

/* ============================================================
   RIGHT DETAIL DRAWER
   ============================================================ */
.detail-drawer, aside.detail-drawer {
  position: fixed;
  top: var(--header-h);
  right: 0;
  bottom: var(--footer-h);
  width: var(--drawer-w);
  background: #ffffff;
  border-left: 1px solid var(--card-border);
  overflow-y: auto;
  z-index: 30;
  padding: 22px 24px 36px;
  box-shadow: -4px 0 16px rgba(0, 0, 0, 0.03);
}

.drawer-empty p { font-size: 0.85rem; color: var(--ink-soft); line-height: 1.5; }
.drawer-course-code { font-family: var(--font-mono); font-size: 0.68rem; font-weight: 600; color: var(--ink-soft); text-transform: uppercase; }
.drawer-title { font-family: var(--font-display); font-size: 1.25rem; font-weight: 600; margin: 4px 0 16px; }
.drawer-section-label { font-family: var(--font-mono); font-size: 0.65rem; font-weight: 700; text-transform: uppercase; color: var(--ink-soft); border-bottom: 1px solid var(--card-border); padding-bottom: 4px; margin: 20px 0 10px; }

.topic-item { padding: 10px 0; border-bottom: 1px dashed var(--card-border); }
.topic-item:last-child { border-bottom: none; }
.topic-title { font-size: 0.88rem; font-weight: 600; }
.topic-objective { font-size: 0.78rem; color: var(--ink-soft); margin-top: 4px; line-height: 1.45; }

/* ============================================================
   MODALS (Restored Dark Slate Course Edit & Clean Modals)
   ============================================================ */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
}

.modal-overlay.hidden { display: none !important; }

/* Course Modal (Dark Slate Theme Restored) */
.modal-container {
  background: #1e222d;
  color: #e1e6ed;
  width: 720px;
  max-width: 90vw;
  max-height: 85vh;
  border-radius: 8px;
  border: 1px solid #333a4a;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-shadow: 0 10px 25px rgba(0,0,0,0.3);
}

.modal-header {
  padding: 16px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid #2a303f;
}

.close-btn, .close-modal-btn {
  background: none;
  border: none;
  color: #8892b0;
  font-size: 24px;
  cursor: pointer;
}

.modal-tabs {
  display: flex;
  background: #161922;
  border-bottom: 1px solid #2a303f;
}

.tab-btn {
  padding: 12px 20px;
  background: none;
  border: none;
  color: #8892b0;
  cursor: pointer;
  font-weight: 600;
}

.tab-btn.active {
  color: #64ffda;
  border-bottom: 2px solid #64ffda;
  background: #1e222d;
}

.modal-body { padding: 20px; overflow-y: auto; flex: 1; }
.tab-content { display: none; }
.tab-content.active { display: block; }

.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-bottom: 16px; }
.form-group { display: flex; flex-direction: column; }
.form-group.full-width { grid-column: span 2; }
.form-group label { font-size: 12px; color: #8892b0; margin-bottom: 4px; }

/* Course Modal Inputs */
#courseModal input[type="text"],
#courseModal input[type="number"],
#courseModal textarea,
#courseModal select,
.form-group input,
.form-group select {
  font-size: 1rem;
  padding: 8px 12px;
  background-color: #111319;
  color: #ffffff;
  border: 1px solid #333a4a;
  border-radius: 4px;
}

#courseModal input::placeholder,
#courseModal textarea::placeholder {
  color: #8892b0;
}

#courseModal input:focus,
#courseModal select:focus {
  outline: none;
  border-color: #64ffda;
  background-color: #111319;
  color: #ffffff;
}

.manager-row {
  display: flex; gap: 8px; align-items: center;
  background: #161922; padding: 10px; border-radius: 4px; margin-bottom: 8px;
}

.modal-footer {
  padding: 16px 20px;
  border-top: 1px solid #2a303f;
  display: flex;
  justify-content: flex-end;
  gap: 10px;
}

/* Nested Module Controls */
.module-row-container {
  background: #1e293b;
  border: 1px solid #334155;
  border-radius: 6px;
  padding: 12px;
  margin-bottom: 12px;
}

.module-header-row { display: flex; gap: 8px; align-items: center; margin-bottom: 10px; }
.nested-section { margin-top: 10px; padding-left: 16px; border-left: 2px solid #3b82f6; }
.nested-section h5 { margin: 4px 0 6px 0; font-size: 1rem; color: #94a3b8; text-transform: uppercase; }
.nested-item-row { display: flex; gap: 6px; margin-bottom: 6px; align-items: center; }

/* ============================================================
   CALENDAR VIEW & CALENDAR MODAL (RESTORED)
   ============================================================ */
.calendar-modal-card {
  background: #ffffff;
  color: var(--ink);
  border-radius: 8px;
  width: 90%;
  max-width: 920px;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  padding: 20px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
}

.calendar-view-container {
  width: 100%;
  height: 100%;
  padding: 24px;
  background: #ffffff;
  display: flex;
  flex-direction: column;
  gap: 16px;
  overflow-y: auto;
}

.calendar-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--card-border);
}

.calendar-title {
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--ink);
}

.calendar-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 16px;
  padding: 12px 0;
}

.cal-week-card {
  border: 1px solid var(--card-border);
  border-radius: 6px;
  background: #f8fafc;
  overflow: hidden;
}

.cal-week-header {
  background: var(--primary-accent);
  color: #ffffff;
  font-weight: 600;
  padding: 8px 12px;
  font-size: 0.875rem;
}

.cal-week-body {
  padding: 10px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.cal-lecture-item {
  background: #ffffff;
  border: 1px solid #cbd5e1;
  border-radius: 4px;
  padding: 6px 8px;
}

.cal-lec-tag {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--primary-accent);
  display: block;
}

.cal-lec-title {
  font-size: 0.85rem;
  color: var(--ink);
}

/* ============================================================
   LEGEND (FOOTER)
   ============================================================ */
.legend-bar {
  height: var(--footer-h);
  border-top: 1px solid var(--card-border);
  background: rgba(255, 255, 255, 0.95);
  display: flex;
  align-items: center;
  gap: 28px;
  padding: 0 28px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--ink-soft);
  position: sticky;
  bottom: 0;
  z-index: 20;
}

.legend-entry, .legend-item { display: flex; align-items: center; gap: 8px; }
.legend-swatch, .legend-line { width: 32px; height: 10px; flex-shrink: 0; }

.legend-swatch.strong, .legend-line.strong {
  background: var(--strong);
  height: 3.5px;
  border-radius: 2px;
}

.legend-swatch.related, .legend-line.related {
  background: var(--related);
  height: 2.5px;
  border-radius: 2px;
}

.legend-swatch.weak, .legend-line.weak {
  background-image: linear-gradient(90deg, var(--weak) 60%, transparent 40%);
  background-size: 8px 2.5px;
  height: 2.5px;
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 860px) {
  :root { --drawer-w: 100%; }
  .board-wrap { width: 100vw; height: calc(100vh - var(--header-h) - var(--footer-h) - 46vh); }
  .detail-drawer { top: auto; height: 46vh; border-left: none; border-top: 1px solid var(--card-border); }
  .app-header { flex-direction: column; height: auto; padding: 12px 16px; gap: 10px; align-items: flex-start; }
  .header-right { flex-wrap: wrap; gap: 10px; }
}

/* Ensure modal form textareas match standard input styles */
.modal-container textarea {
  background-color: #0f172a;
  color: #f8fafc;
  border: 1px solid #334155;
  border-radius: 6px;
  padding: 8px 12px;
  resize: vertical;
}

.modal-container textarea:focus {
  outline: none;
  border-color: #38bdf8;
  box-shadow: 0 0 0 2px rgba(56, 189, 248, 0.2);
}

/* Intro Modal Custom Styling */
.intro-modal-container {
  max-width: 580px;
}

.intro-step-badge {
  font-size: 0.75rem;
  font-weight: 600;
  background-color: #334155;
  color: #38bdf8;
  padding: 3px 8px;
  border-radius: 12px;
  white-space: nowrap; /* Prevents "4 of 5" from breaking onto two lines */
  flex-shrink: 0;      /* Prevents flexbox from squeezing the badge */
}

.intro-modal-body {
  padding: 1.5rem;
  min-height: 120px;
}

.intro-step-content {
  font-size: 0.95rem;
  line-height: 1.6;
  color: #cbd5e1;
}

.intro-step-content b {
  color: #f8fafc;
}

.intro-modal-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* Dots Navigation Indicator */
.intro-dots {
  display: flex;
  gap: 6px;
  align-items: center;
}

.intro-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: #475569;
  cursor: pointer;
  transition: all 0.2s ease;
}

.intro-dot.active {
  background-color: #38bdf8;
  width: 18px;
  border-radius: 4px;
}