/* ============================================================
   Dashboard Styles — The Teaching Goat
   Design system extracted from approved mockup.
   ============================================================ */

/* --- Reset & Variables --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  /* Brand */
  --navy: #1B2A4A;
  --navy-light: #2c4a7c;
  --accent: #1a73e8;
  --accent-light: #e8f0fe;
  --accent-hover: #1557b0;

  /* Text */
  --text: #2c3e50;
  --text-muted: #545b62;
  --text-faint: #8a9199;

  /* Surfaces */
  --border: #c8cfd6;
  --border-light: #dde2e7;
  --card-bg: #ffffff;
  --page-bg: #f4f6f9;

  /* Semantic */
  --success: #1e7e34;
  --warning: #e2a308;
  --error: #d32f2f;
  --cancelled-bg: #fef2f2;
  --cancelled-border: #fca5a5;

  /* Spacing (4px system) */
  --sp-1: 0.25rem;
  --sp-2: 0.5rem;
  --sp-3: 0.75rem;
  --sp-4: 1rem;
  --sp-5: 1.25rem;
  --sp-6: 1.5rem;
  --sp-8: 2rem;
  --sp-10: 2.5rem;
  --sp-12: 3rem;

  /* Radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;

  /* Shadows */
  --shadow-card: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-card-hover: 0 4px 12px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-drawer: -4px 0 24px rgba(0,0,0,0.15);

  /* Transitions */
  --ease: cubic-bezier(0.16, 1, 0.3, 1);

  /* Font */
  --font-body: 'Plus Jakarta Sans', 'Segoe UI', system-ui, sans-serif;

  /* Type scale */
  --text-xs: clamp(0.75rem, 0.7rem + 0.15vw, 0.8125rem);
  --text-sm: clamp(0.8125rem, 0.78rem + 0.2vw, 0.875rem);
  --text-base: clamp(0.875rem, 0.85rem + 0.15vw, 0.9375rem);
  --text-lg: clamp(1rem, 0.95rem + 0.3vw, 1.125rem);
  --text-xl: clamp(1.25rem, 1.1rem + 0.6vw, 1.5rem);

  /* Legacy compat for existing tool styles */
  --dash-accent: #1a73e8;
  --dash-accent-light: #e8f0fe;
  --dash-radius: 0.5rem;
  --dash-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
  --dash-shadow-hover: 0 4px 16px rgba(0, 0, 0, 0.12);
  --dash-muted: #545b62;
}

html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--text);
  background: var(--page-bg);
  line-height: 1.55;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

a { color: inherit; }

/* ============================================================
   ACCESSIBILITY
   ============================================================ */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--sp-4);
  background: var(--accent);
  color: #fff;
  padding: var(--sp-2) var(--sp-4);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 600;
  z-index: 10000;
  text-decoration: none;
  transition: top 0.2s var(--ease);
}
.skip-link:focus {
  top: var(--sp-2);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border-width: 0;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ============================================================
   HEADER
   ============================================================ */
.header {
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-light) 100%);
  color: #fff;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

.header-top {
  display: flex;
  align-items: center;
  padding: var(--sp-3) var(--sp-6);
  gap: var(--sp-4);
}

.logo {
  font-size: var(--text-lg);
  font-weight: 700;
  letter-spacing: 0.06em;
  white-space: nowrap;
  color: #fff;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  flex-shrink: 1;
  min-width: 0;
  max-width: 100%;
  overflow: hidden;
}
.logo > span:not(.logo-orb) {
  overflow: hidden;
  text-overflow: ellipsis;
}
.logo:focus-visible {
  outline-color: rgba(255,255,255,0.9);
}
.logo-emoji {
  font-size: 1.3em;
}
.logo-orb {
  width: 1.35em;
  height: 1.35em;
  border-radius: 50%;
  display: inline-block;
  flex-shrink: 0;
  vertical-align: middle;
  background: radial-gradient(
    circle at 50% 50%,
    #F4B860 0 22%,
    #4FD1C5 30% 45%,
    #182A44 55% 100%
  );
  box-shadow: 0 0 12px rgba(79, 209, 197, 0.45);
}

/* Nav container — fill remaining header space */
.header-top nav {
  flex: 1;
  min-width: 0;
}

/* Mobile hamburger toggle — hidden on desktop, shown <=720px */
.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  flex-shrink: 0;
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.18);
  border-radius: var(--radius-md);
  color: #fff;
  cursor: pointer;
  padding: 0;
  margin-left: auto;
  transition: background 0.18s var(--ease);
}
.nav-toggle:hover { background: rgba(255,255,255,0.16); }
.nav-toggle:focus-visible { outline-color: rgba(255,255,255,0.9); }
.nav-toggle .nav-toggle-bars {
  width: 22px;
  height: 16px;
  position: relative;
  display: inline-block;
}
.nav-toggle .nav-toggle-bars::before,
.nav-toggle .nav-toggle-bars::after,
.nav-toggle .nav-toggle-bars span {
  content: '';
  position: absolute;
  left: 0;
  right: 0;
  height: 2px;
  background: #fff;
  border-radius: 2px;
  transition: transform 0.2s var(--ease), opacity 0.15s var(--ease), top 0.2s var(--ease);
}
.nav-toggle .nav-toggle-bars::before { top: 0; }
.nav-toggle .nav-toggle-bars span    { top: 7px; display: block; }
.nav-toggle .nav-toggle-bars::after  { top: 14px; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::before {
  top: 7px;
  transform: rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::after {
  top: 7px;
  transform: rotate(-45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars span { opacity: 0; }

/* Navigation tabs in header */
.nav-tabs {
  display: flex;
  align-items: stretch;
  gap: 0;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  flex: 1;
  min-width: 0;
}
.nav-tabs::-webkit-scrollbar { display: none; }
.nav-tabs li {
  flex: 1 1 0;
  display: flex;
  min-width: 0;
}

/* Mobile menu / hamburger drawer */
@media (max-width: 720px) {
  .header-top {
    flex-wrap: wrap;
    padding: var(--sp-3) var(--sp-4);
    gap: var(--sp-3);
  }
  .logo {
    font-size: 1rem;
    letter-spacing: 0.04em;
  }
  /* Nav becomes a collapsible panel below the header-top row */
  .header-top nav {
    order: 3;
    flex: 0 0 100%;
    width: 100%;
    max-height: 0;
    overflow: hidden;
    visibility: hidden;
    transition: max-height 0.25s var(--ease), visibility 0s linear 0.25s;
  }
  .header-top nav.is-open {
    max-height: 80vh;
    visibility: visible;
    transition: max-height 0.3s var(--ease), visibility 0s linear 0s;
    overflow-y: auto;
  }
  .nav-toggle { display: inline-flex; }
  .nav-tabs {
    flex-direction: column;
    overflow-x: hidden;
    overflow-y: visible;
    padding: var(--sp-2) 0 var(--sp-3);
    gap: var(--sp-1);
  }
  .nav-tabs li {
    flex: 0 0 auto;
    width: 100%;
  }
  .nav-tab {
    width: 100%;
    justify-content: flex-start;
    min-height: 44px;
    padding: var(--sp-3) var(--sp-4);
    border-radius: var(--radius-md);
    font-size: 1rem;
  }
}

@media (max-width: 380px) {
  .logo { font-size: 0.9375rem; letter-spacing: 0.02em; }
  .logo-orb { width: 1.15em; height: 1.15em; }
}

.nav-tab {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  background: none;
  border: none;
  color: rgba(255,255,255,0.72);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: 600;
  padding: var(--sp-3) var(--sp-4);
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
  cursor: pointer;
  white-space: nowrap;
  position: relative;
  transition: color 0.18s var(--ease), background 0.18s var(--ease);
  text-decoration: none;
}
.nav-tab:hover {
  color: #fff;
  background: rgba(255,255,255,0.1);
}
.nav-tab[aria-selected="true"],
.nav-tab--active {
  color: #fff;
  font-weight: 700;
  background: rgba(255,255,255,0.08);
}
.nav-tab[aria-selected="true"]::after,
.nav-tab--active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: var(--sp-3);
  right: var(--sp-3);
  height: 3px;
  background: #fff;
  border-radius: 3px 3px 0 0;
}

/* Mobile active-tab indicator: vertical bar on the leading edge */
@media (max-width: 720px) {
  .nav-tab[aria-selected="true"]::after,
  .nav-tab--active::after {
    left: 0;
    right: auto;
    bottom: auto;
    top: 20%;
    width: 3px;
    height: 60%;
    border-radius: 0 2px 2px 0;
  }
}
.nav-tab:focus-visible {
  outline-color: rgba(255,255,255,0.9);
}

/* Course info bar */
.course-bar {
  background: rgba(0,0,0,0.15);
  padding: var(--sp-2) var(--sp-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--sp-2) var(--sp-6);
  font-size: var(--text-sm);
}
.course-title {
  font-weight: 600;
  font-size: var(--text-base);
  color: #fff;
}
.course-meta {
  display: flex;
  gap: var(--sp-4);
  flex-wrap: wrap;
  color: rgba(255,255,255,0.78);
  font-size: var(--text-xs);
}
.course-meta-item {
  display: flex;
  align-items: center;
  gap: var(--sp-1);
}

/* ============================================================
   MAIN CONTENT
   ============================================================ */
.main {
  max-width: 1320px;
  margin: 0 auto;
  padding: var(--sp-6);
}

/* Tab panels */
.tab-panel { display: none; }
.tab-panel.active {
  display: block;
  animation: fadeIn 0.25s var(--ease);
}
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ============================================================
   ANNOUNCEMENTS
   ============================================================ */
.announcements-section {
  background: var(--card-bg);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--sp-4) var(--sp-5);
  margin-bottom: var(--sp-5);
}
.announcements-header {
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  user-select: none;
  font-size: var(--text-base);
  font-weight: 700;
  color: var(--text);
  transition: color 0.15s;
}
.announcements-header:hover { color: var(--navy); }
.announcements-toggle {
  font-size: var(--text-xs);
  color: var(--text-faint);
  transition: transform 0.25s ease;
  margin-left: auto;
}
.announcements-toggle.collapsed { transform: rotate(-90deg); }
.announcements-body {
  transition: max-height 0.3s ease, opacity 0.25s ease, padding 0.25s ease;
  overflow: hidden;
}
.announcements-body.collapsed {
  max-height: 0 !important;
  opacity: 0;
  padding-top: 0;
  padding-bottom: 0;
}

/* News items */
.news-item {
  padding: var(--sp-3) 0;
  border-bottom: 1px solid var(--border-light);
}
.news-item:last-child { border-bottom: none; }
.news-date {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.03em;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.new-badge {
  display: inline-block;
  background: var(--error);
  color: #fff;
  font-size: 0.6rem;
  font-weight: 800;
  padding: 0.1rem 0.4rem;
  border-radius: 2rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  animation: pulse-badge 2s ease-in-out infinite;
}
@keyframes pulse-badge {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.8; transform: scale(1.05); }
}
.news-title {
  font-weight: 500;
  font-size: var(--text-base);
  color: var(--text);
  margin: var(--sp-1) 0;
}
.news-body {
  font-size: var(--text-sm);
  color: var(--text-muted);
  line-height: 1.5;
}

/* ============================================================
   CARDS GRID (Lectures Tab)
   ============================================================ */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--sp-4);
}
@media (max-width: 540px) {
  .cards-grid { grid-template-columns: 1fr; }
}

/* Class card */
.class-card {
  background: var(--card-bg);
  border: 2px solid #d1d5db;
  border-radius: var(--radius-lg);
  padding: var(--sp-4);
  cursor: pointer;
  transition: box-shadow 0.2s var(--ease), border-color 0.2s var(--ease), transform 0.18s var(--ease);
  position: relative;
  display: flex;
  flex-direction: column;
  gap: var(--sp-2);
}
.class-card:hover {
  box-shadow: var(--shadow-card-hover);
  border-color: var(--accent);
  transform: translateY(-1px);
}
.class-card:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* Current week accent */
.class-card--current {
  border-left: 4px solid var(--accent);
}

/* Cancelled */
.class-card--cancelled {
  background: var(--cancelled-bg);
  border-color: var(--cancelled-border);
  opacity: 0.82;
}
.class-card--cancelled:hover {
  border-color: var(--cancelled-border);
  transform: none;
  box-shadow: var(--shadow-card);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-2);
}
.card-number {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-muted);
}
.card-date {
  font-size: var(--text-xs);
  color: var(--text-faint);
}
.card-badge-week {
  background: var(--accent-light);
  color: var(--accent);
  font-size: 0.6875rem;
  font-weight: 600;
  padding: 1px 6px;
  border-radius: 999px;
  white-space: nowrap;
}
.card-badge-cancelled {
  background: #fee2e2;
  color: #dc2626;
  font-size: 0.6875rem;
  font-weight: 600;
  padding: 1px 6px;
  border-radius: 999px;
  white-space: nowrap;
}

.card-topic {
  font-size: var(--text-base);
  font-weight: 700;
  color: var(--text);
  line-height: 1.3;
}
.card-topic--cancelled {
  text-decoration: line-through;
  color: var(--text-faint);
}

.card-chapter {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-1);
  background: var(--page-bg);
  border: 1px solid var(--border-light);
  color: var(--text-muted);
  font-size: var(--text-xs);
  font-weight: 500;
  padding: 2px 8px;
  border-radius: 999px;
  width: fit-content;
}

.card-icons {
  display: flex;
  gap: var(--sp-2);
  margin-top: auto;
  padding-top: var(--sp-1);
}
.card-icon {
  font-size: 0.9375rem;
  opacity: 0.7;
}

/* ============================================================
   DRAWER (Slide-in panel)
   ============================================================ */
.drawer-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.35);
  z-index: 200;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s var(--ease), visibility 0.3s;
}
.drawer-backdrop.open {
  opacity: 1;
  visibility: visible;
}

.drawer {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  left: auto;
  width: 450px;
  max-width: 100vw;
  background: var(--card-bg);
  z-index: 210;
  transform: translateX(100%);
  transition: transform 0.3s var(--ease);
  overflow-y: auto;
  overflow-x: hidden;
  box-shadow: var(--shadow-drawer);
  word-wrap: break-word;
  overflow-wrap: break-word;
}
.drawer.open {
  transform: translateX(0);
}

.drawer-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  padding: var(--sp-5) var(--sp-5) var(--sp-4);
  border-bottom: 1px solid var(--border-light);
  position: sticky;
  top: 0;
  background: var(--card-bg);
  z-index: 1;
  min-width: 0;
}
.drawer-title-group {
  flex: 1;
  min-width: 0;
}
.drawer-number {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.drawer-date {
  font-size: var(--text-sm);
  color: var(--text-muted);
  margin-top: 2px;
}
.drawer-topic {
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--text);
  margin-top: var(--sp-2);
  line-height: 1.25;
  overflow-wrap: break-word;
  word-break: break-word;
}
.drawer-chapter {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-1);
  background: var(--page-bg);
  border: 1px solid var(--border-light);
  color: var(--text-muted);
  font-size: var(--text-xs);
  font-weight: 500;
  padding: 3px 10px;
  border-radius: 999px;
  margin-top: var(--sp-2);
}

.drawer-close {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 1.25rem;
  width: 2rem;
  height: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  cursor: pointer;
  flex-shrink: 0;
  transition: background 0.15s, color 0.15s;
}
.drawer-close:hover {
  background: var(--page-bg);
  color: var(--text);
}

.drawer-body {
  padding: var(--sp-5);
  display: flex;
  flex-direction: column;
  gap: var(--sp-5);
}

/* Material links (button style) */
.drawer-material-links {
  display: flex;
  flex-direction: column;
  gap: var(--sp-2);
}
.material-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: var(--sp-3) var(--sp-4);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  border: 1.5px solid var(--border);
  background: var(--card-bg);
  color: var(--text);
  transition: all 0.18s var(--ease);
}
.material-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-light);
}

/* Assignments in drawer */
.drawer-section-title {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--text);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--sp-2);
}

.assignment-card {
  background: var(--page-bg);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: var(--sp-3) var(--sp-4);
  margin-bottom: var(--sp-2);
}
.assignment-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-2);
  flex-wrap: wrap;
}
.assignment-title {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--text);
  overflow-wrap: break-word;
  word-break: break-word;
}
.assignment-meta {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  flex-wrap: wrap;
}
.badge {
  display: inline-flex;
  align-items: center;
  font-size: 0.6875rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 999px;
  white-space: nowrap;
}
.badge--project {
  background: #ede9fe;
  color: #6d28d9;
}
.badge--worksheet {
  background: #dbeafe;
  color: #1d4ed8;
}
.badge--bug-bounty {
  background: #fef3c7;
  color: #92400e;
}
.badge--points {
  background: #d1fae5;
  color: #065f46;
}

.assignment-due {
  font-size: var(--text-xs);
  color: var(--text-muted);
  margin-top: var(--sp-1);
}

.assignment-toggle {
  background: none;
  border: none;
  color: var(--accent);
  font-size: var(--text-xs);
  font-weight: 600;
  cursor: pointer;
  padding: var(--sp-1) 0;
  margin-top: var(--sp-1);
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-family: var(--font-body);
}
.assignment-toggle:hover {
  color: var(--accent-hover);
}

.assignment-instructions {
  display: none;
  margin-top: var(--sp-2);
  padding-top: var(--sp-2);
  border-top: 1px solid var(--border-light);
  font-size: var(--text-xs);
  color: var(--text-muted);
  line-height: 1.6;
}
.assignment-instructions.open {
  display: block;
}

.canvas-reminder {
  background: #fffbeb;
  border: 1px solid #fcd34d;
  border-radius: var(--radius-md);
  padding: var(--sp-3) var(--sp-4);
  font-size: var(--text-xs);
  color: #92400e;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: var(--sp-2);
}

/* ============================================================
   TOOLS TAB
   ============================================================ */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
  gap: var(--sp-4);
}
@media (max-width: 540px) {
  .tools-grid { grid-template-columns: 1fr; }
}

.tool-card {
  background: var(--card-bg);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.tool-card-body {
  padding: var(--sp-5);
}
.tool-icon {
  font-size: 2rem;
  margin-bottom: var(--sp-2);
}
.tool-title {
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--text);
  margin-bottom: var(--sp-1);
}
.tool-desc {
  font-size: var(--text-sm);
  color: var(--text-muted);
  margin-bottom: var(--sp-3);
  line-height: 1.5;
}
.tool-topics {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-1);
  margin-bottom: var(--sp-4);
}
.tool-topic-tag {
  font-size: var(--text-xs);
  background: var(--accent-light);
  color: var(--accent);
  padding: 2px 8px;
  border-radius: 999px;
  font-weight: 500;
}
.tool-actions {
  display: flex;
  gap: var(--sp-2);
  flex-wrap: wrap;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: var(--sp-2) var(--sp-4);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  border: none;
  transition: all 0.18s var(--ease);
  font-family: var(--font-body);
}
.btn--primary {
  background: var(--accent);
  color: #fff;
}
.btn--primary:hover {
  background: var(--accent-hover);
}
.btn--outline {
  background: transparent;
  color: var(--text-muted);
  border: 1.5px solid var(--border);
}
.btn--outline:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.tool-embed-area {
  display: none;
  border-top: 1px solid var(--border-light);
  background: var(--page-bg);
}
.tool-embed-area.open {
  display: block;
}
.tool-embed-area iframe {
  width: 100%;
  height: 750px;
  border: none;
  display: block;
}
@media (max-width: 768px) {
  .tool-embed-area iframe { height: 600px; }
}

/* External tool cards (Node 7 judging boards) */
.tool-card--external {
  border-color: var(--accent);
  border-width: 2px;
  position: relative;
}
.tool-title-row {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  flex-wrap: wrap;
  margin-bottom: var(--sp-1);
}
.tool-title-row .tool-title {
  margin-bottom: 0;
}
.tool-badge {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  padding: 2px 10px;
  border-radius: 999px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  line-height: 1.6;
  white-space: nowrap;
}
.tool-badge--event {
  background: var(--accent);
  color: #fff;
}

/* ============================================================
   SCHEDULE TAB
   ============================================================ */
.schedule-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-6);
}
@media (max-width: 768px) {
  .schedule-layout {
    grid-template-columns: 1fr;
  }
}

.schedule-section-title {
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--text);
  margin-bottom: var(--sp-4);
  padding-bottom: var(--sp-2);
  border-bottom: 2px solid var(--navy);
}

.schedule-table {
  width: 100%;
  border-collapse: collapse;
}
.schedule-table th,
.schedule-table td {
  text-align: left;
  padding: var(--sp-2) var(--sp-3);
  font-size: var(--text-sm);
  border-bottom: 1px solid var(--border-light);
}
.schedule-table th {
  font-weight: 600;
  color: var(--text-muted);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  background: var(--page-bg);
}
.schedule-table tr:hover td {
  background: var(--accent-light);
}
.schedule-table .current-row td {
  background: var(--accent-light);
  font-weight: 600;
}
.schedule-table .cancelled-row td {
  color: var(--text-faint);
  text-decoration: line-through;
}

/* Assignments list in schedule tab */
.assignments-list {
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
}
.assignment-list-item {
  background: var(--card-bg);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--sp-3) var(--sp-4);
}
.assignment-list-title {
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--text);
}
.assignment-list-meta {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  margin-top: var(--sp-1);
  flex-wrap: wrap;
}
.assignment-list-due {
  font-size: var(--text-xs);
  color: var(--text-muted);
}

/* Assignment sections in schedule */
.assignments-section { margin-bottom: var(--sp-3); }
.assignments-section:last-child { margin-bottom: 0; }
.assignments-section-header {
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: var(--sp-1) var(--sp-3);
  border-radius: var(--radius-sm);
  margin-bottom: var(--sp-1);
}
.assignments-section-header.current {
  color: #fff;
  background: var(--accent);
}
.assignments-section-header.upcoming {
  color: var(--text-muted);
  background: var(--page-bg);
}
.assignments-section-header.past {
  color: var(--text-muted);
  background: var(--page-bg);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.assignments-section-header.past::before {
  content: "\25B8";
  font-size: 0.7rem;
  transition: transform 0.2s ease;
}
details[open] > .assignments-section-header.past::before {
  transform: rotate(90deg);
}
.assignments-past-section > summary::-webkit-details-marker { display: none; }
.assignments-past-section > summary { list-style: none; }
.assignments-past-list .assignment-item { opacity: 0.65; }
.assignments-past-list .assignment-item:hover { opacity: 1; }

/* Assignment items */
.assignment-item {
  padding: var(--sp-3) 0;
  border-bottom: 1px solid var(--border-light);
}
.assignment-item:last-child { border-bottom: none; }
.assignment-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.type-badge {
  display: inline-block;
  padding: 0.15rem 0.55rem;
  border-radius: 2rem;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: #fff;
}
.type-badge.worksheet { background: #1a73e8; }
.type-badge.lab { background: #28a745; }
.type-badge.exam { background: #dc3545; }
.type-badge.quiz { background: #6f42c1; }
.type-badge.project { background: #c2410c; }
.type-badge.homework { background: #17a2b8; }
.type-badge.semester_project { background: #c2410c; }
.type-badge.notebook { background: #1565c0; }
.type-badge.problem_set { background: #7b1fa2; }
.type-badge.bug_bounty { background: #be185d; }
.points-badge {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-muted);
}
.past-due {
  color: var(--error);
  font-weight: 600;
}
.assignment-details { margin-top: var(--sp-2); }
.assignment-details summary {
  font-size: var(--text-sm);
  color: var(--accent);
  cursor: pointer;
  font-weight: 500;
}
.assignment-details .details-body {
  font-size: var(--text-sm);
  color: var(--text-muted);
  padding: var(--sp-2) 0 0 var(--sp-2);
  line-height: 1.5;
}

/* ============================================================
   SLIDESHOW GRID
   ============================================================ */
.lectures-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--sp-4);
}
.lecture-card {
  background: var(--page-bg);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--sp-4);
  transition: all 0.15s ease;
}
.lecture-card:hover {
  background: var(--card-bg);
  border-color: var(--accent);
  box-shadow: var(--shadow-card-hover);
}
.lecture-card a {
  text-decoration: none;
  color: inherit;
  display: block;
}
.lecture-number {
  font-size: var(--text-xs);
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.lecture-title {
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--text);
  margin: var(--sp-1) 0;
  line-height: 1.3;
}
.lecture-date {
  font-size: var(--text-xs);
  color: var(--text-muted);
}

/* ============================================================
   PLACEHOLDER TABS
   ============================================================ */
.placeholder-tab {
  background: var(--card-bg);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--sp-8);
  text-align: center;
  color: var(--text-muted);
}
.placeholder-tab h2 {
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--text);
  margin-bottom: var(--sp-2);
}
.placeholder-tab p {
  font-size: var(--text-sm);
  max-width: 48ch;
  margin: 0 auto;
}
.placeholder-tab .bug-bounty-content p {
  max-width: none;
  margin: initial;
}

/* Bug bounty styling */
.bug-bounty-hero {
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-light) 100%);
  color: #fff;
  border-radius: var(--radius-lg);
  padding: var(--sp-6);
  margin-bottom: var(--sp-5);
  text-align: center;
}
.bug-bounty-hero h4 {
  font-size: var(--text-xl);
  margin: 0 0 var(--sp-2) 0;
  color: #fff;
}
.bug-bounty-hero p {
  margin: var(--sp-1) 0;
  font-size: var(--text-base);
  color: rgba(255,255,255,0.9);
}
.bug-bounty-note {
  background: rgba(255,255,255,0.1);
  border-radius: var(--radius-md);
  padding: var(--sp-2) var(--sp-3);
  margin-top: var(--sp-3);
  font-size: var(--text-sm);
  color: rgba(255,255,255,0.8);
  text-align: center;
}
.bug-bounty-how, .bug-bounty-rubric, .bug-bounty-rules { margin-bottom: var(--sp-5); }
.bug-bounty-how h5, .bug-bounty-rubric h5, .bug-bounty-rules h5 {
  font-size: var(--text-base);
  font-weight: 700;
  color: var(--text);
  margin-bottom: var(--sp-2);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}
.bug-bounty-how ol {
  padding-left: var(--sp-5);
  font-size: var(--text-sm);
  line-height: 1.7;
}
.bug-bounty-rules ul {
  padding-left: var(--sp-5);
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--text-muted);
}
.bug-bounty-download {
  text-align: center;
  padding: var(--sp-5);
  background: var(--page-bg);
  border-radius: var(--radius-lg);
  border: 2px dashed var(--border);
}

/* ============================================================
   COMING SOON / EMPTY STATE
   ============================================================ */
.coming-soon {
  text-align: center;
  padding: var(--sp-8) var(--sp-4);
  color: var(--text-muted);
  font-size: var(--text-sm);
}
.coming-soon .coming-soon-icon {
  font-size: 2rem;
  display: block;
  margin-bottom: var(--sp-2);
}

/* ============================================================
   LOADING SKELETON
   ============================================================ */
.skeleton {
  position: relative;
  overflow: hidden;
  background: #f0f0f0;
  border-radius: var(--radius-sm);
}
.skeleton::after {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  background: linear-gradient(90deg, transparent 0%, rgba(255,255,255,0.5) 50%, transparent 100%);
  animation: shimmer 1.5s ease-in-out infinite;
}
@keyframes shimmer {
  0% { transform: translateX(-100%); }
  100% { transform: translateX(100%); }
}
.skeleton-block {
  height: 4rem;
  margin-bottom: var(--sp-3);
}

/* ============================================================
   UTILITY
   ============================================================ */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

/* ============================================================
   SITE FOOTER
   ============================================================ */
main, .main {
  flex: 1;
  width: 100%;
}
.site-footer {
  background: var(--navy);
  color: rgba(255,255,255,0.7);
  padding: var(--sp-4) var(--sp-6);
  margin-top: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--sp-2);
  font-size: var(--text-xs);
}
.site-footer a {
  color: rgba(255,255,255,0.7);
  text-decoration: none;
  transition: color 0.15s;
}
.site-footer a:hover {
  color: #fff;
}
.site-footer-links {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
}
.site-footer-links svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

/* BETA banner — shown on every page above the main header */
.beta-banner {
  background: #fff8e1;
  color: #7a5a00;
  border-bottom: 1px solid #e2a308;
  text-align: center;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  padding: 6px 12px;
  line-height: 1.3;
}
.beta-banner a {
  color: inherit;
  text-decoration: underline;
}
.site-footer .beta-footer-line {
  display: block;
  color: rgba(255, 248, 225, 0.9);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  margin-top: 6px;
}