:root {
  --primary: #6366f1;
  --primary-foreground: #ffffff;
  --primary-hover: #4f46e5;
  --background: #f8fafc;
  --card: #ffffff;
  --sidebar-bg: #0f172a;
  --sidebar-text: #94a3b8;
  --sidebar-hover: #1e293b;
  --sidebar-active: #6366f1;
  --sidebar-active-text: #ffffff;
  --sidebar-width: 260px;
  --muted: #f1f5f9;
  --muted-foreground: #64748b;
  --border: #e2e8f0;
  --success: #22c55e;
  --success-bg: #dcfce7;
  --warning: #f59e0b;
  --warning-bg: #fef3c7;
  --destructive: #ef4444;
  --destructive-bg: #fee2e2;
  --text: #0f172a;
  --text-muted: #64748b;
  --radius: 0.5rem;
  --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
}

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

html, body {
  height: 100%;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  font-size: 14px;
  color: var(--text);
  background: var(--background);
  line-height: 1.5;
}

a {
  text-decoration: none;
  color: inherit;
}

/* =====================
   LAYOUT
   ===================== */
.app-layout {
  display: flex;
  min-height: 100vh;
}

/* =====================
   SIDEBAR
   ===================== */
.sidebar {
  width: var(--sidebar-width);
  background: var(--sidebar-bg);
  color: var(--sidebar-text);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 100;
  transition: transform 0.3s ease;
  overflow-y: auto;
}

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1.5rem 1.25rem;
  border-bottom: 1px solid rgba(255,255,255,0.07);
}

.sidebar-logo-icon {
  width: 36px;
  height: 36px;
  background: var(--primary);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.sidebar-logo-icon svg {
  width: 20px;
  height: 20px;
  fill: white;
}

.sidebar-logo-text {
  font-size: 1.1rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: 0.025em;
}

.sidebar-logo-sub {
  font-size: 0.7rem;
  color: var(--sidebar-text);
  margin-top: 1px;
}

.sidebar-nav {
  flex: 1;
  padding: 1rem 0.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.125rem;
}

.nav-section-title {
  font-size: 0.65rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: rgba(148, 163, 184, 0.6);
  padding: 0.75rem 0.75rem 0.375rem;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.625rem 0.875rem;
  border-radius: var(--radius);
  color: var(--sidebar-text);
  font-size: 0.875rem;
  font-weight: 500;
  transition: background 0.15s, color 0.15s;
  cursor: pointer;
}

.nav-item:hover {
  background: var(--sidebar-hover);
  color: #e2e8f0;
}

.nav-item.active {
  background: var(--primary);
  color: var(--sidebar-active-text);
}

.nav-item.active svg {
  color: var(--sidebar-active-text);
}

.nav-item svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  opacity: 0.8;
}

.nav-item.active svg {
  opacity: 1;
}

.sidebar-footer {
  padding: 1rem 0.75rem;
  border-top: 1px solid rgba(255,255,255,0.07);
}

.user-info {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.625rem 0.875rem;
  border-radius: var(--radius);
}

.user-avatar {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 600;
  flex-shrink: 0;
}

.user-name {
  font-size: 0.875rem;
  font-weight: 500;
  color: #e2e8f0;
  line-height: 1.2;
}

.user-role {
  font-size: 0.7rem;
  color: var(--sidebar-text);
}

.logout-btn {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.625rem 0.875rem;
  border-radius: var(--radius);
  color: var(--sidebar-text);
  font-size: 0.875rem;
  font-weight: 500;
  transition: background 0.15s, color 0.15s;
  margin-top: 0.25rem;
  cursor: pointer;
  width: 100%;
  border: none;
  background: transparent;
  text-align: left;
}

.logout-btn:hover {
  background: rgba(239, 68, 68, 0.15);
  color: #f87171;
}

.logout-btn svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

/* =====================
   MAIN CONTENT
   ===================== */
.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* =====================
   TOPBAR
   ===================== */
.topbar {
  height: 60px;
  background: var(--card);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.5rem;
  position: sticky;
  top: 0;
  z-index: 50;
}

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

.sidebar-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.375rem;
  border-radius: var(--radius);
  color: var(--text-muted);
}

.sidebar-toggle:hover {
  background: var(--muted);
}

.topbar-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
}

.topbar-right {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.topbar-avatar {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
}

/* =====================
   PAGE CONTENT
   ===================== */
.page-content {
  padding: 1.5rem;
  flex: 1;
}

.page-header {
  margin-bottom: 1.5rem;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.page-header > div:first-child,
.page-header > h1 {
  flex: 1;
}

.page-header h1 {
  font-size: 1.375rem;
  font-weight: 700;
  color: var(--text);
}

.page-header p {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

/* =====================
   STATS CARDS
   ===================== */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.stat-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  box-shadow: var(--shadow);
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
}

.stat-card-body {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

.stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
}

.stat-value {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text);
  line-height: 1;
}

.stat-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.stat-icon svg {
  width: 22px;
  height: 22px;
}

.stat-icon-blue {
  background: #dbeafe;
  color: #3b82f6;
}

.stat-icon-green {
  background: var(--success-bg);
  color: #16a34a;
}

.stat-icon-yellow {
  background: var(--warning-bg);
  color: #d97706;
}

.stat-icon-purple {
  background: #ede9fe;
  color: #7c3aed;
}

/* =====================
   CARDS
   ===================== */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.card-header {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.card-title {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text);
}

.card-body {
  padding: 1.25rem;
}

/* =====================
   TABLES
   ===================== */
.table-wrapper {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}

thead th {
  text-align: left;
  padding: 0.625rem 1rem;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-muted);
  background: var(--muted);
  border-bottom: 1px solid var(--border);
}

tbody tr {
  border-bottom: 1px solid var(--border);
  transition: background 0.12s;
}

tbody tr:hover {
  background: var(--muted);
}

tbody tr:last-child {
  border-bottom: none;
}

tbody td {
  padding: 0.75rem 1rem;
  color: var(--text);
  vertical-align: middle;
}

/* =====================
   BADGES
   ===================== */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.625rem;
  border-radius: 9999px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  white-space: nowrap;
}

.badge-success {
  background: var(--success-bg);
  color: #15803d;
}

.badge-warning {
  background: var(--warning-bg);
  color: #92400e;
}

.badge-destructive {
  background: var(--destructive-bg);
  color: #b91c1c;
}

.badge-muted {
  background: var(--muted);
  color: var(--text-muted);
}

.badge-primary {
  background: #ede9fe;
  color: #4f46e5;
}

.badge-info {
  background: #dbeafe;
  color: #1d4ed8;
}

/* =====================
   BUTTONS
   ===================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  font-size: 0.875rem;
  font-weight: 500;
  border: none;
  cursor: pointer;
  transition: background 0.15s, box-shadow 0.15s;
  text-decoration: none;
}

.btn-primary {
  background: var(--primary);
  color: white;
}

.btn-primary:hover {
  background: var(--primary-hover);
}

.btn-outline {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-outline:hover {
  background: var(--muted);
}

.btn-secondary {
  background: var(--muted);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--border);
}

.btn-destructive {
  background: var(--destructive);
  color: white;
}

.btn-destructive:hover {
  background: #dc2626;
}

.btn-sm {
  padding: 0.35rem 0.75rem;
  font-size: 0.8rem;
}

.btn svg {
  width: 16px;
  height: 16px;
}

/* =====================
   GROUPS GRID
   ===================== */
.groups-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}

.group-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  box-shadow: var(--shadow);
  transition: box-shadow 0.15s;
}

.group-card:hover {
  box-shadow: var(--shadow-md);
}

.group-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 0.75rem;
}

.group-name {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text);
}

.group-description {
  font-size: 0.8125rem;
  color: var(--text-muted);
  margin-bottom: 0.875rem;
  line-height: 1.4;
}

.group-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

.group-meta-item {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

/* =====================
   DASHBOARD GRID
   ===================== */
.dashboard-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

@media (max-width: 900px) {
  .dashboard-grid {
    grid-template-columns: 1fr;
  }
}

/* =====================
   EMPTY STATE
   ===================== */
.empty-state {
  text-align: center;
  padding: 3rem 1.5rem;
  color: var(--text-muted);
}

.empty-state svg {
  width: 48px;
  height: 48px;
  margin: 0 auto 1rem;
  opacity: 0.35;
}

.empty-state p {
  font-size: 0.9rem;
}

/* =====================
   ALERT
   ===================== */
.alert {
  padding: 0.875rem 1.125rem;
  border-radius: var(--radius);
  font-size: 0.875rem;
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.625rem;
}

.alert-error {
  background: var(--destructive-bg);
  color: #b91c1c;
  border: 1px solid #fca5a5;
}

.alert svg {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}

/* =====================
   TASK LIST
   ===================== */
.task-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.task-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem;
  background: var(--muted);
  border-radius: var(--radius);
  font-size: 0.875rem;
}

.task-item-info {
  display: flex;
  flex-direction: column;
  gap: 0.125rem;
}

.task-item-title {
  font-weight: 500;
  color: var(--text);
}

.task-item-deadline {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* =====================
   LOGIN PAGE
   ===================== */
.login-page {
  min-height: 100vh;
  background: linear-gradient(135deg, #0f172a 0%, #1e1b4b 50%, #0f172a 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.login-card {
  background: rgba(255, 255, 255, 0.05);
  backdrop-filter: blur(16px);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 1rem;
  padding: 2.5rem;
  width: 100%;
  max-width: 400px;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.login-header {
  text-align: center;
  margin-bottom: 2rem;
}

.login-logo {
  width: 56px;
  height: 56px;
  background: var(--primary);
  border-radius: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1.25rem;
}

.login-logo svg {
  width: 32px;
  height: 32px;
  fill: white;
}

.login-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: #f1f5f9;
  margin-bottom: 0.375rem;
}

.login-subtitle {
  font-size: 0.875rem;
  color: rgba(148, 163, 184, 0.8);
}

.login-form {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

.form-label {
  font-size: 0.8125rem;
  font-weight: 500;
  color: #cbd5e1;
}

.form-input {
  width: 100%;
  padding: 0.625rem 0.875rem;
  background: rgba(255, 255, 255, 0.07);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: var(--radius);
  color: #f1f5f9;
  font-size: 0.9rem;
  outline: none;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.form-input::placeholder {
  color: rgba(148, 163, 184, 0.5);
}

.form-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.login-btn {
  width: 100%;
  padding: 0.75rem;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: var(--radius);
  font-size: 0.9375rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
  margin-top: 0.5rem;
}

.login-btn:hover {
  background: var(--primary-hover);
}

.login-btn:active {
  transform: scale(0.99);
}

.login-error {
  background: rgba(239, 68, 68, 0.15);
  border: 1px solid rgba(239, 68, 68, 0.3);
  color: #fca5a5;
  padding: 0.75rem;
  border-radius: var(--radius);
  font-size: 0.875rem;
  text-align: center;
}

/* =====================
   FORM / DETAIL PAGES
   ===================== */
.form-page { max-width: 720px; }
.form-section { margin-bottom: 1.5rem; }
.field-group { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.field { display: flex; flex-direction: column; gap: 0.4rem; margin-bottom: 1rem; }
.field label { font-size: 0.8rem; font-weight: 500; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.04em; }
.field input, .field select, .field textarea {
  padding: 0.55rem 0.75rem; border: 1px solid var(--border); border-radius: var(--radius);
  font-size: 0.875rem; background: var(--card); color: var(--text); width: 100%;
}
.field input:focus, .field select:focus, .field textarea:focus {
  outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px rgba(99,102,241,.12);
}
.checkbox-group { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.checkbox-label { display: flex; align-items: center; gap: 0.4rem; font-size: 0.875rem;
  padding: 0.3rem 0.6rem; border: 1px solid var(--border); border-radius: var(--radius);
  cursor: pointer; background: var(--card); }
.checkbox-label:has(input:checked) { border-color: var(--primary); background: rgba(99,102,241,.06); color: var(--primary); }
.form-actions { display: flex; gap: 0.75rem; padding-top: 1rem; border-top: 1px solid var(--border); }
.detail-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1.25rem; }
.detail-field { display: flex; flex-direction: column; gap: 0.25rem; }
.detail-label { font-size: 0.75rem; font-weight: 600; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.05em; }
.detail-value { font-size: 0.9rem; color: var(--text); }
.action-row { display: flex; gap: 0.5rem; align-items: center; }

/* =====================
   SUBJECTS
   ===================== */
.subjects-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

/* =====================
   RESPONSIVE
   ===================== */
@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
  }

  .sidebar-toggle {
    display: flex;
  }

  .stats-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 480px) {
  .stats-grid {
    grid-template-columns: 1fr;
  }

  .page-content {
    padding: 1rem;
  }

  .login-card {
    padding: 1.75rem 1.25rem;
  }
}