:root {
  color-scheme: dark;
  --bg: #0b1120;
  --bg-alt: rgba(15, 23, 42, 0.7);
  --surface: rgba(30, 41, 59, 0.55);
  --surface-hover: rgba(51, 65, 85, 0.65);
  --text: #f8fafc;
  --text-muted: #94a3b8;
  --primary: #38bdf8;
  --primary-glow: rgba(56, 189, 248, 0.35);
  --accent: #2dd4bf;
  --accent-glow: rgba(45, 212, 191, 0.3);
  --border: rgba(255, 255, 255, 0.08);
  --border-hover: rgba(56, 189, 248, 0.4);
  --success: #22c55e;
  --warning: #f59e0b;
  --danger: #ef4444;
  --purple: #a855f7;
  --radius-sm: 8px;
  --radius: 16px;
  --radius-lg: 24px;
  --radius-full: 9999px;
  --shadow: 0 20px 40px -15px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 25px 50px -12px rgba(0, 0, 0, 0.7);
  --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
  font-family: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  background-color: var(--bg);
  background-image: 
    radial-gradient(at 0% 0%, rgba(56, 189, 248, 0.12) 0px, transparent 50%),
    radial-gradient(at 100% 100%, rgba(45, 212, 191, 0.1) 0px, transparent 50%);
  background-attachment: fixed;
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  width: min(1280px, calc(100% - 3rem));
  margin: 0 auto;
}

/* Typography */
h1, h2, h3, h4 {
  color: #ffffff;
  font-weight: 700;
  line-height: 1.25;
}

.text-muted { color: var(--text-muted); }
.text-success { color: var(--success); }
.text-warning { color: var(--warning); }
.text-danger { color: var(--danger); }
.small { font-size: 0.85rem; }
.text-center { text-align: center; }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.4rem;
  border-radius: var(--radius-full);
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid transparent;
  transition: var(--transition);
  text-decoration: none;
}

.btn-sm {
  padding: 0.45rem 1rem;
  font-size: 0.85rem;
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  border-radius: 50%;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #0b1120;
  box-shadow: 0 4px 20px var(--primary-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px var(--primary-glow);
  opacity: 0.95;
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.06);
  color: var(--text);
  border-color: var(--border);
  backdrop-filter: blur(10px);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.12);
  border-color: rgba(255, 255, 255, 0.25);
  transform: translateY(-2px);
}

.btn-outline {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}

.btn-outline:hover {
  background: rgba(56, 189, 248, 0.1);
  border-color: var(--primary);
  color: var(--primary);
  transform: translateY(-2px);
}

.btn-danger {
  background: rgba(239, 68, 68, 0.15);
  color: #fca5a5;
  border-color: rgba(239, 68, 68, 0.3);
}

.btn-danger:hover {
  background: var(--danger);
  color: #ffffff;
}

/* Header & Navigation */
.app-header {
  background: rgba(11, 17, 32, 0.85);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  padding: 1.2rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.brand {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.brand-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius);
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #0b1120;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  box-shadow: 0 0 20px var(--primary-glow);
}

.brand-title {
  font-size: 1.4rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.badge-tag {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  background: rgba(56, 189, 248, 0.15);
  color: var(--primary);
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(56, 189, 248, 0.3);
}

.brand-subtitle {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.8rem;
}

/* Nav Tabs */
.nav-tabs-bar {
  background: rgba(15, 23, 42, 0.6);
  border-bottom: 1px solid var(--border);
  padding: 0.5rem 0;
}

.tabs-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.tabs {
  display: flex;
  gap: 0.5rem;
  overflow-x: auto;
}

.tab-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 0.6rem 1.2rem;
  border-radius: var(--radius-full);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  transition: var(--transition);
  white-space: nowrap;
}

.tab-btn:hover {
  color: #ffffff;
  background: rgba(255, 255, 255, 0.05);
}

.tab-btn.active {
  background: var(--primary);
  color: #0b1120;
  box-shadow: 0 4px 15px var(--primary-glow);
}

.system-time {
  font-family: 'Fira Code', monospace;
  font-size: 0.85rem;
  color: var(--accent);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

/* Main Content & Tabs */
.main-content {
  padding: 2.5rem 0;
}

.tab-content {
  display: none;
  animation: fadeIn 0.35s ease;
}

.tab-content.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Cards & Layout */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.8rem;
  backdrop-filter: blur(16px);
  box-shadow: var(--shadow);
  transition: var(--transition);
  margin-bottom: 2rem;
}

.card:hover {
  border-color: var(--border-hover);
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.section-title {
  margin-bottom: 2rem;
}

/* Metrics Cards */
.metrics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.metric-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  display: flex;
  align-items: center;
  gap: 1.2rem;
  backdrop-filter: blur(12px);
  transition: var(--transition);
}

.metric-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-hover);
}

.metric-icon {
  width: 56px;
  height: 56px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  flex-shrink: 0;
}

.icon-blue { background: rgba(56, 189, 248, 0.15); color: var(--primary); }
.icon-emerald { background: rgba(45, 212, 191, 0.15); color: var(--accent); }
.icon-purple { background: rgba(168, 85, 247, 0.15); color: var(--purple); }
.icon-amber { background: rgba(245, 158, 11, 0.15); color: var(--warning); }

.metric-label {
  font-size: 0.85rem;
  color: var(--text-muted);
  display: block;
}

.metric-value {
  font-size: 1.8rem;
  font-weight: 800;
  color: #ffffff;
  margin: 0.1rem 0;
}

.metric-sub {
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* Dashboard Grid */
.dashboard-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.8rem;
}

/* Department Bars */
.department-bars {
  display: grid;
  gap: 1.2rem;
}

.dept-bar-item {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.dept-info {
  display: flex;
  justify-content: space-between;
  font-size: 0.9rem;
  font-weight: 600;
}

.bar-track {
  height: 10px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.bar-fill {
  height: 100%;
  border-radius: var(--radius-full);
  background: linear-gradient(90deg, var(--primary), var(--accent));
  transition: width 0.8s ease;
}

/* Leaderboard List */
.leaderboard-list {
  display: grid;
  gap: 0.8rem;
}

.leader-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.8rem 1rem;
  background: rgba(255, 255, 255, 0.03);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}

.leader-info {
  display: flex;
  align-items: center;
  gap: 0.8rem;
}

.leader-rank {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: rgba(56, 189, 248, 0.15);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.85rem;
}

.leader-gpa {
  font-family: 'Fira Code', monospace;
  font-weight: 700;
  color: var(--accent);
}

/* Filter Card */
.filter-card {
  padding: 1.2rem 1.8rem;
  margin-bottom: 1.5rem;
}

.search-filter-grid {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  align-items: center;
}

.search-input-wrapper {
  position: relative;
  flex-grow: 1;
  min-width: 260px;
}

.search-icon {
  position: absolute;
  left: 1.2rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
}

.search-input {
  padding-left: 2.8rem !important;
}

.filter-group {
  display: flex;
  gap: 0.8rem;
  flex-wrap: wrap;
}

.form-control {
  background: rgba(15, 23, 42, 0.8);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.65rem 1rem;
  color: var(--text);
  font-family: inherit;
  font-size: 0.9rem;
  outline: none;
  transition: var(--transition);
}

.form-control:focus {
  border-color: var(--primary);
  box-shadow: 0 0 12px var(--primary-glow);
}

/* Data Tables */
.table-card {
  padding: 0;
  overflow: hidden;
}

.table-card .card-header {
  padding: 1.5rem 1.8rem 1rem;
  margin-bottom: 0;
}

.table-header-flex {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.table-actions {
  display: flex;
  gap: 0.8rem;
}

.table-responsive {
  overflow-x: auto;
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.92rem;
}

.data-table th {
  background: rgba(15, 23, 42, 0.9);
  color: var(--text-muted);
  font-weight: 600;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  text-transform: uppercase;
  font-size: 0.78rem;
  letter-spacing: 0.05em;
}

.data-table td {
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  vertical-align: middle;
}

.data-table tbody tr {
  transition: var(--transition);
}

.data-table tbody tr:hover {
  background: rgba(255, 255, 255, 0.04);
}

.status-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-full);
  font-size: 0.78rem;
  font-weight: 700;
}

.status-active {
  background: rgba(34, 197, 94, 0.12);
  color: #4ade80;
  border: 1px solid rgba(34, 197, 94, 0.3);
}

.status-leave {
  background: rgba(245, 158, 11, 0.12);
  color: #fbbf24;
  border: 1px solid rgba(245, 158, 11, 0.3);
}

.status-probation {
  background: rgba(239, 68, 68, 0.12);
  color: #f87171;
  border: 1px solid rgba(239, 68, 68, 0.3);
}

.gpa-pill {
  font-family: 'Fira Code', monospace;
  font-weight: 700;
  color: var(--primary);
  background: rgba(56, 189, 248, 0.1);
  padding: 0.2rem 0.5rem;
  border-radius: var(--radius-sm);
}

.action-btns {
  display: flex;
  gap: 0.4rem;
  justify-content: center;
}

.btn-action {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: var(--transition);
}

.btn-action:hover {
  background: var(--primary);
  color: #0b1120;
  border-color: var(--primary);
}

.btn-action.delete:hover {
  background: var(--danger);
  color: #ffffff;
  border-color: var(--danger);
}

/* Attendance Controls */
.attendance-controls {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  flex-wrap: wrap;
  gap: 1.2rem;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.control-group label {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 600;
}

.control-actions {
  display: flex;
  gap: 0.8rem;
}

.att-switch {
  display: flex;
  gap: 0.4rem;
}

.att-opt {
  padding: 0.35rem 0.8rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-muted);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.att-opt.present.active { background: rgba(34, 197, 94, 0.2); color: #4ade80; border-color: var(--success); }
.att-opt.absent.active { background: rgba(239, 68, 68, 0.2); color: #f87171; border-color: var(--danger); }
.att-opt.late.active { background: rgba(245, 158, 11, 0.2); color: #fbbf24; border-color: var(--warning); }

/* Courses Grid */
.courses-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.8rem;
}

.course-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.8rem;
  transition: var(--transition);
}

.course-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-hover);
}

.course-code {
  font-family: 'Fira Code', monospace;
  font-size: 0.82rem;
  color: var(--accent);
  background: rgba(45, 212, 191, 0.1);
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-sm);
  display: inline-block;
  margin-bottom: 0.8rem;
}

.course-title {
  font-size: 1.2rem;
  margin-bottom: 0.6rem;
}

.course-instructor {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 1.2rem;
}

.course-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-top: 1px solid var(--border);
  padding-top: 1rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Modal Dialogs */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(11, 17, 32, 0.85);
  backdrop-filter: blur(12px);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.modal-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.modal-card {
  width: min(640px, 100%);
  max-height: 90vh;
  overflow-y: auto;
  background: #0f172a;
  border: 1px solid var(--border-hover);
  border-radius: var(--radius-lg);
  padding: 2.2rem;
  position: relative;
  box-shadow: var(--shadow-lg);
  transform: translateY(20px);
  transition: transform 0.3s ease;
}

.modal-lg {
  width: min(800px, 100%);
}

.modal-overlay.active .modal-card {
  transform: translateY(0);
}

.modal-close {
  position: absolute;
  top: 1.2rem;
  right: 1.5rem;
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 1.8rem;
  cursor: pointer;
  transition: var(--transition);
}

.modal-close:hover {
  color: #ffffff;
}

.modal-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.8rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 1.2rem;
}

.modal-header-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  background: rgba(56, 189, 248, 0.15);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
}

.student-form {
  display: grid;
  gap: 1.2rem;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.form-group label {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 600;
}

.modal-footer {
  display: flex;
  justify-content: flex-end;
  gap: 0.8rem;
  margin-top: 1.8rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--border);
}

/* Transcript View */
.transcript-header {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 1.5rem;
}

.transcript-avatar {
  width: 70px;
  height: 70px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #0b1120;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8rem;
  font-weight: 800;
}

.transcript-meta {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1rem;
  margin-bottom: 1.5rem;
  background: rgba(255, 255, 255, 0.03);
  padding: 1.2rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.meta-box span {
  display: block;
  font-size: 0.78rem;
  color: var(--text-muted);
}

.meta-box strong {
  font-size: 1rem;
  color: #ffffff;
}

/* Toast Notification */
.toast {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background: var(--accent);
  color: #0b1120;
  font-weight: 700;
  padding: 0.8rem 1.5rem;
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  transform: translateY(20px);
  transition: var(--transition);
  pointer-events: none;
  z-index: 2000;
}

.toast.show {
  opacity: 1;
  transform: translateY(0);
}

/* Responsive Breakpoints */
@media (max-width: 992px) {
  .dashboard-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .header-container, .tabs-container {
    flex-direction: column;
    gap: 1rem;
    align-items: flex-start;
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .attendance-controls {
    flex-direction: column;
    align-items: stretch;
  }

  .control-actions {
    flex-direction: column;
  }
}