:root {
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --primary-light: #eef2ff;
  --secondary: #0ea5e9;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --dark: #0f172a;
  --gray-900: #111827;
  --gray-800: #1f2937;
  --gray-700: #374151;
  --gray-600: #4b5563;
  --gray-500: #6b7280;
  --gray-200: #e5e7eb;
  --gray-100: #f3f4f6;
  --gray-50: #f9fafb;
  --white: #ffffff;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

body {
  background-color: #f1f5f9;
  color: var(--gray-800);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header */
.navbar {
  background: var(--white);
  border-bottom: 1px solid var(--gray-200);
  padding: 1rem 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-icon {
  font-size: 26px;
  background: var(--primary-light);
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
}

.brand-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--gray-900);
  letter-spacing: -0.02em;
}

.brand-subtitle {
  font-size: 0.75rem;
  color: var(--gray-500);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

/* User Pill */
.user-pill {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 6px 14px;
  background: var(--gray-100);
  border-radius: 9999px;
  font-size: 0.875rem;
  font-weight: 500;
}

.role-badge {
  display: inline-flex;
  align-items: center;
  padding: 3px 10px;
  border-radius: 9999px;
  font-size: 0.725rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.role-admin { background: #fee2e2; color: #991b1b; }
.role-staff { background: #fef3c7; color: #92400e; }
.role-student { background: #dbeafe; color: #1e40af; }
.role-verifier { background: #f3e8ff; color: #6b21a8; }

/* Status Badges */
.status-badge {
  display: inline-flex;
  padding: 2px 8px;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
}
.status-active { background: #d1fae5; color: #065f46; }
.status-revoked { background: #fee2e2; color: #991b1b; }
.status-expired { background: #e5e7eb; color: #4b5563; }

/* Main Container */
.container {
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
  padding: 2rem 1.5rem;
  flex: 1;
}

/* Quick demo bar */
.demo-bar {
  background: linear-gradient(135deg, #1e1b4b 0%, #312e81 100%);
  color: white;
  padding: 12px 20px;
  border-radius: var(--radius-lg);
  margin-bottom: 24px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  box-shadow: var(--shadow-md);
}

.demo-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.demo-btn {
  background: rgba(255, 255, 255, 0.15);
  border: 1px solid rgba(255, 255, 255, 0.25);
  color: white;
  padding: 5px 12px;
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}

.demo-btn:hover {
  background: white;
  color: var(--primary);
  transform: translateY(-1px);
}

/* Tabs */
.tabs-header {
  display: flex;
  gap: 8px;
  border-bottom: 2px solid var(--gray-200);
  margin-bottom: 24px;
}

.tab-btn {
  padding: 12px 20px;
  background: none;
  border: none;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--gray-500);
  cursor: pointer;
  position: relative;
  transition: all 0.2s;
  display: flex;
  align-items: center;
  gap: 8px;
}

.tab-btn.active {
  color: var(--primary);
}

.tab-btn.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--primary);
}

/* Cards & Sections */
.card {
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--gray-200);
  margin-bottom: 24px;
}

.card-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--gray-900);
  margin-bottom: 6px;
}

.card-desc {
  font-size: 0.875rem;
  color: var(--gray-500);
  margin-bottom: 20px;
}

/* Buttons */
.btn {
  padding: 8px 16px;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.875rem;
  cursor: pointer;
  border: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: all 0.15s ease-in-out;
}

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

.btn-secondary {
  background: var(--gray-100);
  color: var(--gray-700);
}
.btn-secondary:hover {
  background: var(--gray-200);
}

.btn-danger {
  background: #fee2e2;
  color: var(--danger);
}
.btn-danger:hover {
  background: var(--danger);
  color: white;
}

.btn-sm {
  padding: 4px 10px;
  font-size: 0.775rem;
}

/* Tables */
.table-responsive {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

th {
  background: var(--gray-50);
  padding: 12px 16px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--gray-500);
  border-bottom: 1px solid var(--gray-200);
}

td {
  padding: 14px 16px;
  font-size: 0.875rem;
  color: var(--gray-700);
  border-bottom: 1px solid var(--gray-200);
  vertical-align: middle;
}

tr:hover td {
  background: #f8fafc;
}

/* Digital Certificate Card (Student Presentation) */
.cert-card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
  gap: 24px;
}

.cert-card {
  background: white;
  border-radius: var(--radius-xl);
  border: 2px solid #e0e7ff;
  box-shadow: var(--shadow-md);
  padding: 24px;
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: transform 0.2s, box-shadow 0.2s;
}

.cert-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}

.cert-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 6px;
  background: linear-gradient(90deg, #4f46e5, #06b6d4);
}

.cert-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 14px;
}

.cert-institution {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--primary);
}

.cert-uid-badge {
  font-family: monospace;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 3px 8px;
  background: #f1f5f9;
  border-radius: 4px;
  border: 1px solid #cbd5e1;
}

.cert-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--gray-900);
  margin-bottom: 8px;
}

.cert-recipient {
  font-size: 0.95rem;
  color: var(--gray-700);
  margin-bottom: 14px;
}

.cert-meta {
  font-size: 0.8rem;
  color: var(--gray-500);
  margin-bottom: 16px;
  line-height: 1.5;
}

.cert-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-top: 1px solid var(--gray-100);
  padding-top: 14px;
}

/* Modals */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  backdrop-filter: blur(2px);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease-in-out;
}

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

.modal-box {
  background: white;
  width: 90%;
  max-width: 580px;
  border-radius: var(--radius-xl);
  padding: 28px;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 25px 50px -12px rgb(0 0 0 / 0.25);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.close-btn {
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--gray-400);
  cursor: pointer;
}

.form-group {
  margin-bottom: 16px;
}

.form-group label {
  display: block;
  font-size: 0.825rem;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--gray-700);
}

.form-control {
  width: 100%;
  padding: 9px 12px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  transition: border-color 0.2s;
}

.form-control:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.15);
}

/* Verification Result Box */
.verify-result {
  padding: 20px;
  border-radius: var(--radius-lg);
  margin-top: 20px;
}

.verify-valid {
  background: #ecfdf5;
  border: 1px solid #a7f3d0;
  color: #065f46;
}

.verify-invalid {
  background: #fef2f2;
  border: 1px solid #fecaca;
  color: #991b1b;
}

.verify-revoked {
  background: #fffbeb;
  border: 1px solid #fde68a;
  color: #92400e;
}