/**
 * 3-Pane Layout, Brand Header in Left Pane, and Neumorphic UI Components - Zen Mode
 * Full side-by-side 3-pane layout for all screens > 768px.
 * Clean 3-button bottom navigation bar for mobile / narrow tablet screens (<= 768px).
 */

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

body {
  font-family: var(--font-family);
  background-color: var(--md-sys-color-background);
  color: var(--md-sys-color-on-background);
  font-size: var(--font-size-sm);
  line-height: 1.55;
  height: 100vh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

/* Main 3-Pane Container (Full 100vh on desktop/tablet > 768px) */
.app-body {
  display: flex;
  flex: 1;
  overflow: hidden;
  height: 100vh;
  position: relative;
}

/* Left Pane: Course Catalog (262px on desktop > 768px) */
.left-pane {
  width: 262px;
  flex-shrink: 0;
  background-color: var(--md-sys-color-surface);
  border-right: 1px solid var(--md-sys-color-outline-variant);
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow: hidden;
}

/* Brand Header integrated at the top of Left Pane */
.left-pane-brand {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 2px 0 6px 0;
  border-bottom: 1px solid var(--md-sys-color-outline-variant);
  margin-bottom: 6px;
}

.brand-title-wrap {
  display: flex;
  align-items: center;
  gap: 6px;
}

.brand-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--md-sys-color-primary);
  line-height: 1;
}

.brand-title {
  font-size: 13.5px;
  font-weight: 700;
  color: var(--md-sys-color-on-surface);
  letter-spacing: -0.2px;
}

/* Middle Pane: Period Calendar Grid (Maximized Space) */
.middle-pane {
  flex: 1;
  min-width: 0;
  background-color: var(--md-sys-color-background);
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow: hidden;
}

/* Right Pane: Dual-Mode (Syllabus / AI) */
.right-pane {
  width: 380px;
  flex-shrink: 0;
  background-color: var(--md-sys-color-surface);
  border-left: 1px solid var(--md-sys-color-outline-variant);
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow: hidden;
}

/* Right Pane Segmented Tab Header - Soft Sunken Container */
.right-pane-tabs {
  display: flex;
  align-items: center;
  background-color: var(--md-sys-color-surface-container);
  border-bottom: 1px solid var(--md-sys-color-outline-variant);
  padding: 5px var(--space-xs);
  gap: 6px;
  box-shadow: var(--neumorph-inset);
  flex-shrink: 0;
}

.pane-tab-btn {
  flex: 1;
  border: none;
  background: transparent;
  padding: 8px var(--space-sm);
  font-family: inherit;
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: var(--md-sys-color-on-surface-variant);
  border-radius: var(--radius-xs);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  transition: var(--transition-smooth);
}

.pane-tab-btn.active {
  background-color: var(--md-sys-color-surface);
  color: var(--md-sys-color-on-surface);
  box-shadow: var(--neumorph-raised);
}

.right-tab-content {
  display: none;
  flex: 1;
  overflow: hidden;
}

.right-tab-content.active {
  display: flex;
  flex-direction: column;
}

/* Neumorphic Buttons - Subtle Lift */
.m3-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 6px 14px;
  font-family: inherit;
  font-size: var(--font-size-xs);
  font-weight: 600;
  border-radius: var(--radius-full);
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  transition: var(--transition-smooth);
  line-height: 1.2;
}

.m3-button.filled {
  background-color: var(--md-sys-color-primary);
  color: var(--md-sys-color-on-primary);
  box-shadow: var(--neumorph-flat);
}
.m3-button.filled:hover {
  filter: brightness(1.15);
  box-shadow: var(--neumorph-raised);
}
.m3-button.filled:active {
  box-shadow: var(--neumorph-inset);
  transform: translateY(1px);
}

.m3-button.filled-danger {
  background-color: #52525b;
  color: #ffffff;
  box-shadow: var(--neumorph-flat);
}
.m3-button.filled-danger:hover {
  background-color: #3f3f46;
  box-shadow: var(--neumorph-raised);
}
.m3-button.filled-danger:active {
  box-shadow: var(--neumorph-inset);
}

.m3-button.tonal {
  background-color: var(--md-sys-color-surface-container);
  color: var(--md-sys-color-on-surface);
  border: 1px solid var(--md-sys-color-outline-variant);
  box-shadow: var(--neumorph-flat);
}
.m3-button.tonal:hover {
  background-color: var(--md-sys-color-surface);
  box-shadow: var(--neumorph-raised);
}
.m3-button.tonal:active {
  box-shadow: var(--neumorph-inset);
  transform: translateY(1px);
}

.m3-btn-icon {
  background: transparent;
  border: none;
  font-size: 16px;
  cursor: pointer;
  padding: 6px;
  border-radius: var(--radius-full);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--md-sys-color-on-surface-variant);
  transition: var(--transition-smooth);
}
.m3-btn-icon:hover {
  background-color: var(--md-sys-color-surface-container-high);
  box-shadow: var(--neumorph-flat);
}
.m3-btn-icon:active {
  box-shadow: var(--neumorph-inset);
}

/* M3 Selects - Soft Neumorphic Elevation */
.m3-select {
  font-family: inherit;
  font-size: 11.5px;
  padding: 5px 8px;
  border-radius: var(--radius-xs);
  border: 1px solid var(--md-sys-color-outline-variant);
  background-color: var(--md-sys-color-surface);
  color: var(--md-sys-color-on-surface);
  cursor: pointer;
  box-shadow: var(--neumorph-flat);
  transition: var(--transition-smooth);
}
.m3-select:hover {
  box-shadow: var(--neumorph-raised);
}
.m3-select:focus {
  outline: none;
  box-shadow: var(--neumorph-inset);
}

/* Loader */
#appLoader {
  position: fixed;
  inset: 0;
  background-color: var(--md-sys-color-background);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  transition: opacity 0.3s ease;
}
#appLoader.fade-out {
  opacity: 0;
  pointer-events: none;
}
.spinner {
  width: 34px;
  height: 34px;
  border: 2px solid var(--md-sys-color-outline-variant);
  border-top-color: var(--md-sys-color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin-bottom: var(--space-sm);
}
@keyframes spin {
  to { transform: rotate(360deg); }
}

/* 3-Button Mobile Navigation Bar (Hidden by default on screens > 768px) */
.mobile-nav-bar {
  display: none;
}

/* =========================================================
 * Mobile Mode (STRICTLY <= 768px)
 * 3-Button View Switching rather than sliding panes
 * ========================================================= */
@media (max-width: 768px) {
  .app-body {
    height: calc(100vh - 56px);
  }

  /* Hide all 3 panes by default on mobile */
  .left-pane,
  .middle-pane,
  .right-pane {
    display: none !important;
    width: 100% !important;
    height: 100% !important;
    border: none !important;
    flex-shrink: 0 !important;
  }

  /* Show only the active view based on data-mobile-view attribute */
  .app-body[data-mobile-view="catalog"] .left-pane {
    display: flex !important;
  }

  .app-body[data-mobile-view="calendar"] .middle-pane {
    display: flex !important;
  }

  .app-body[data-mobile-view="details"] .right-pane {
    display: flex !important;
  }

  /* Fixed 3-Button Bottom Navigation Bar */
  .mobile-nav-bar {
    display: flex;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 56px;
    background-color: var(--md-sys-color-surface);
    border-top: 1px solid var(--md-sys-color-outline-variant);
    box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.06);
    z-index: 100;
    align-items: center;
    justify-content: space-around;
    padding: 0 var(--space-xs);
  }

  .mobile-nav-btn {
    flex: 1;
    height: 44px;
    border: none;
    background: transparent;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 2px;
    border-radius: var(--radius-xs);
    cursor: pointer;
    color: var(--md-sys-color-on-surface-variant);
    font-family: inherit;
    transition: var(--transition-smooth);
  }

  .mobile-nav-btn .nav-icon {
    font-size: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
  }

  .mobile-nav-btn .nav-label {
    font-size: 11px;
    font-weight: 600;
    line-height: 1;
  }

  .mobile-nav-btn.active {
    background-color: var(--md-sys-color-surface-container);
    color: var(--md-sys-color-primary);
    box-shadow: var(--neumorph-inset);
  }

  .mobile-nav-btn.active .nav-label {
    font-weight: 700;
  }
}