/* Import Inter font from Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

/* =================================
   CSS Custom Properties (Design System) - Light & Dark Mode
   ================================= */
:root {
  /* Light Mode Colors - Bold & Vibrant */
  --color-background: #f8fafc;
  --color-surface: #ffffff;
  --color-card: #ffffff;
  --color-text-primary: #0f172a;
  --color-text-secondary: #475569;
  --color-text-muted: #94a3b8;

  /* Accent Colors - Bold & Vibrant */
  --color-primary: #6366f1;        /* Indigo */
  --color-primary-hover: #4f46e5;
  --color-secondary: #8b5cf6;      /* Purple */
  --color-accent: #06b6d4;         /* Cyan */
  --color-success: #10b981;        /* Green */
  --color-error: #ef4444;          /* Red */
  --color-warning: #f59e0b;        /* Amber */

  /* Border & Divider - Minimal */
  --color-border: #f1f5f9;
  --color-divider: #e2e8f0;

  /* Shadows - Dramatic elevation */
  --shadow-sm: 0 2px 4px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 16px -2px rgba(0, 0, 0, 0.1), 0 2px 8px -2px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 12px 32px -8px rgba(0, 0, 0, 0.18), 0 4px 12px -4px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 24px 64px -12px rgba(0, 0, 0, 0.25), 0 8px 24px -8px rgba(0, 0, 0, 0.15);

  /* Gradient - Bold and vibrant */
  --gradient-primary: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
  --gradient-accent: linear-gradient(135deg, #ec4899 0%, #f97316 100%);
  --gradient-success: linear-gradient(135deg, #06b6d4 0%, #10b981 100%);
  --gradient-background: linear-gradient(180deg, #f8fafc 0%, #f1f5f9 100%);

  /* Spacing System - Base 8px */
  --spacing-1: 0.5rem;   /* 8px */
  --spacing-2: 1rem;     /* 16px */
  --spacing-3: 1.5rem;   /* 24px */
  --spacing-4: 2rem;     /* 32px */
  --spacing-5: 2.5rem;   /* 40px */
  --spacing-6: 3rem;     /* 48px */
  --spacing-8: 4rem;     /* 64px */

  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
  --font-size-xs: 0.75rem;   /* 12px */
  --font-size-sm: 0.875rem;  /* 14px */
  --font-size-base: 1rem;    /* 16px */
  --font-size-lg: 1.125rem;  /* 18px */
  --font-size-xl: 1.25rem;   /* 20px */
  --font-size-2xl: 1.5rem;   /* 24px */
  --font-size-3xl: 1.875rem; /* 30px */
  --font-size-4xl: 2.25rem;  /* 36px */

  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 200ms ease-in-out;
  --transition-slow: 300ms ease-in-out;
}

/* Dark Mode Colors */
[data-theme="dark"] {
  --color-background: #0f172a;        /* Slate 900 */
  --color-surface: #1e293b;           /* Slate 800 */
  --color-card: #1e293b;
  --color-text-primary: #f1f5f9;      /* Slate 100 */
  --color-text-secondary: #94a3b8;    /* Slate 400 */
  --color-text-muted: #64748b;        /* Slate 500 */

  --color-border: #334155;            /* Slate 700 */
  --color-divider: #475569;           /* Slate 600 */

  --shadow-sm: 0 2px 4px 0 rgba(0, 0, 0, 0.5);
  --shadow-md: 0 4px 16px -2px rgba(0, 0, 0, 0.6), 0 2px 8px -2px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 12px 32px -8px rgba(0, 0, 0, 0.7), 0 4px 12px -4px rgba(0, 0, 0, 0.5);
  --shadow-xl: 0 24px 64px -12px rgba(0, 0, 0, 0.8), 0 8px 24px -8px rgba(0, 0, 0, 0.6);

  --gradient-background: linear-gradient(180deg, #0f172a 0%, #1e293b 100%);
}

/* =================================
   Base Styles
   ================================= */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-text-primary);
  background: var(--gradient-background);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background var(--transition-base), color var(--transition-base);
}

#app {
  min-height: 100vh;
  width: 100%;
}

/* =================================
   Typography
   ================================= */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.2;
  color: var(--color-text-primary);
}

h1 {
  font-size: 3rem;
  margin-bottom: var(--spacing-4);
  font-weight: 800;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
}

h2 {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-3);
}

h3 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-2);
}

p {
  margin-bottom: var(--spacing-2);
  color: var(--color-text-secondary);
}

/* =================================
   Dashboard & Layout
   ================================= */
.dashboard {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-8) var(--spacing-4);
}

.dashboard header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-6);
  flex-wrap: wrap;
  gap: var(--spacing-3);
}

.sort-indicator {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-1);
  margin-top: var(--spacing-2);
  padding: var(--spacing-1) var(--spacing-2);
  background: var(--color-background);
  border: 2px solid var(--color-divider);
  border-radius: 8px;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

.sort-indicator__icon {
  font-size: var(--font-size-base);
}

.sort-indicator__text {
  font-weight: 500;
}

.theme-toggle-container {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
}

/* Dark Mode Toggle Button */
.theme-toggle {
  position: relative;
  width: 60px;
  height: 32px;
  background: var(--color-border);
  border: none;
  border-radius: 100px;
  cursor: pointer;
  transition: all var(--transition-base);
  padding: 0;
  overflow: hidden;
}

.theme-toggle:hover {
  transform: scale(1.05);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

[data-theme="dark"] .theme-toggle:hover {
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

.theme-toggle-slider {
  position: absolute;
  top: 4px;
  left: 4px;
  width: 24px;
  height: 24px;
  background: white;
  border-radius: 50%;
  transition: transform var(--transition-base);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-sm);
}

[data-theme="dark"] .theme-toggle {
  background: var(--color-primary-hover);
}

[data-theme="dark"] .theme-toggle-slider {
  transform: translateX(28px);
  background: #94a3b8;
}

.theme-toggle-icon {
  font-size: 14px;
  transition: opacity var(--transition-fast);
}

.theme-toggle-icon.sun {
  opacity: 1;
}

.theme-toggle-icon.moon {
  opacity: 0;
  position: absolute;
}

[data-theme="dark"] .theme-toggle-icon.sun {
  opacity: 0;
}

[data-theme="dark"] .theme-toggle-icon.moon {
  opacity: 1;
}

/* =================================
   Stats Container
   ================================= */
.stats-container {
  display: flex;
  gap: var(--spacing-4);
  margin-bottom: var(--spacing-6);
  flex-wrap: wrap;
}

.stats-box {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
  background: var(--color-card);
  padding: var(--spacing-4) var(--spacing-5);
  border-radius: 16px;
  box-shadow: var(--shadow-md);
  flex: 1;
  min-width: 200px;
  transition: all var(--transition-base);
  border: 1px solid var(--color-border);
}

.stats-box:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.stats-box__icon {
  font-size: 2.5rem;
  line-height: 1;
}

.stats-box__content {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-1);
}

.stats-box__value {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1;
}

.stats-box__label {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* =================================
   Grid System
   ================================= */
.grid-container {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-4);
  width: 100%;
}

/* =================================
   Exam Card Component - Modern Design
   ================================= */
.exam-card {
  background: var(--color-card);
  border-radius: 24px;
  padding: var(--spacing-6);
  box-shadow: var(--shadow-lg);
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  border: none;
  position: relative;
  overflow: hidden;
}

.exam-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 5px;
  background: var(--gradient-primary);
  opacity: 1;
}

.exam-card:hover {
  transform: translateY(-8px) scale(1.01);
  box-shadow: 0 32px 72px -16px rgba(0, 0, 0, 0.2), 0 12px 32px -8px rgba(99, 102, 241, 0.15);
}

.exam-card__header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: var(--spacing-3);
}

.exam-card__title {
  font-size: 1.75rem;
  color: var(--color-text-primary);
  margin: 0;
  font-weight: 800;
  letter-spacing: -0.01em;
}

.exam-card__urgency-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-1);
  padding: 8px 18px;
  border-radius: 100px;
  font-size: var(--font-size-xs);
  font-weight: 700;
  white-space: nowrap;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.exam-card__urgency-badge.urgency-low {
  background: linear-gradient(135deg, #10b981 0%, #059669 100%);
  color: white;
  border: none;
}

.exam-card__urgency-badge.urgency-medium {
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  color: white;
  border: none;
}

.exam-card__urgency-badge.urgency-high {
  background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
  color: white;
  border: none;
}

[data-theme="dark"] .exam-card__urgency-badge.urgency-low {
  background: linear-gradient(135deg, #10b981 0%, #059669 100%);
  color: white;
}

[data-theme="dark"] .exam-card__urgency-badge.urgency-medium {
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  color: white;
}

[data-theme="dark"] .exam-card__urgency-badge.urgency-high {
  background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
  color: white;
}

.exam-card__meta {
  display: flex;
  gap: var(--spacing-4);
  margin-bottom: var(--spacing-3);
  flex-wrap: wrap;
}

.exam-card__subject,
.exam-card__date {
  display: flex;
  align-items: center;
  gap: var(--spacing-1);
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  margin: 0;
}

.exam-card__subject::before {
  content: '📚';
  font-size: var(--font-size-base);
}

.exam-card__date::before {
  content: '📅';
  font-size: var(--font-size-base);
}

/* Topics Section with Collapse/Expand */
.exam-card__topics {
  margin-top: var(--spacing-3);
  margin-bottom: var(--spacing-3);
}

.exam-card__topics-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  padding: var(--spacing-2);
  border-radius: 8px;
  background-color: var(--color-border);
  transition: background-color var(--transition-fast);
  user-select: none;
}

.exam-card__topics-title {
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
  color: var(--color-text-primary);
  font-size: var(--font-size-base);
  font-weight: 600;
  margin: 0;
}

.exam-card__topics-count {
  background: var(--color-primary);
  color: white;
  padding: 2px 8px;
  border-radius: 12px;
  font-size: var(--font-size-xs);
  font-weight: 600;
}

.exam-card__topics-toggle {
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-1);
  color: var(--color-text-primary);
  font-size: var(--font-size-xl);
  transition: transform var(--transition-base);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}

.exam-card__topics-toggle.expanded {
  transform: rotate(180deg);
}

.exam-card__topics-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow);
}

.exam-card__topics-content.expanded {
  max-height: 1000px;
}

.exam-card__topics-list {
  list-style: none;
  padding: var(--spacing-2) 0 0 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-2);
}

.exam-card__topic-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
  padding: var(--spacing-2) var(--spacing-3);
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.12) 0%, rgba(139, 92, 246, 0.12) 100%);
  border-radius: 12px;
  border-left: 3px solid var(--color-primary);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.04);
  transition: all var(--transition-base);
}

.exam-card__topic-item.completed {
  background: linear-gradient(135deg, rgba(16, 185, 129, 0.12) 0%, rgba(6, 182, 212, 0.12) 100%);
  border-left-color: var(--color-success);
  opacity: 0.7;
}

.exam-card__topic-checkbox {
  width: 18px;
  height: 18px;
  cursor: pointer;
  accent-color: var(--color-success);
  flex-shrink: 0;
}

.exam-card__topic-text {
  color: var(--color-text-primary);
  font-size: var(--font-size-sm);
  flex: 1;
  transition: all var(--transition-base);
}

.exam-card__topic-item.completed .exam-card__topic-text {
  text-decoration: line-through;
  color: var(--color-text-secondary);
}

.exam-card__topic-delete-btn {
  background: transparent;
  border: none;
  color: var(--color-error);
  cursor: pointer;
  font-size: var(--font-size-xl);
  line-height: 1;
  padding: var(--spacing-1);
  border-radius: 4px;
  transition: all var(--transition-fast);
  opacity: 0;
}

.exam-card__topic-item:hover .exam-card__topic-delete-btn {
  opacity: 1;
}

.exam-card__topic-delete-btn:hover {
  background: var(--color-error);
  color: white;
}

/* Actions */
.exam-card__actions {
  display: flex;
  gap: var(--spacing-2);
  margin-top: var(--spacing-4);
  padding-top: var(--spacing-3);
  border-top: 1px solid var(--color-border);
}

.exam-card__edit-btn {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.1) 0%, rgba(139, 92, 246, 0.1) 100%);
  border: 2px solid transparent;
  color: var(--color-primary);
  padding: 12px 28px;
  border-radius: 14px;
  cursor: pointer;
  font-weight: 700;
  font-size: var(--font-size-sm);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.exam-card__edit-btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--gradient-primary);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.exam-card__edit-btn span {
  position: relative;
  z-index: 1;
}

.exam-card__edit-btn:hover {
  color: white;
  transform: translateY(-3px);
  box-shadow: 0 8px 24px rgba(99, 102, 241, 0.4);
}

.exam-card__edit-btn:hover::before {
  opacity: 1;
}

.exam-card__edit-btn:active {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.exam-card__delete-btn {
  background: linear-gradient(135deg, rgba(239, 68, 68, 0.1) 0%, rgba(220, 38, 38, 0.1) 100%);
  border: 2px solid transparent;
  color: var(--color-error);
  padding: 12px 28px;
  border-radius: 14px;
  cursor: pointer;
  font-weight: 700;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.exam-card__delete-btn:hover {
  background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
  color: white;
  transform: translateY(-3px);
  box-shadow: 0 8px 24px rgba(239, 68, 68, 0.4);
}

.exam-card__delete-btn:active {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
}

/* =================================
   Utility Classes
   ================================= */

/* Flexbox */
.d-flex {
  display: flex;
}

.d-block {
  display: block;
}

.justify-between {
  justify-content: space-between;
}

.justify-end {
  justify-content: flex-end;
}

.align-center {
  align-items: center;
}

.flex-grow {
  flex-grow: 1;
}

.gap-1 {
  gap: var(--spacing-1);
}

.gap-2 {
  gap: var(--spacing-2);
}

.gap-3 {
  gap: var(--spacing-3);
}

/* Spacing */
.mb-1 { margin-bottom: var(--spacing-1); }
.mb-2 { margin-bottom: var(--spacing-2); }
.mb-3 { margin-bottom: var(--spacing-3); }
.mb-4 { margin-bottom: var(--spacing-4); }
.mt-1 { margin-top: var(--spacing-1); }
.mt-2 { margin-top: var(--spacing-2); }
.mt-3 { margin-top: var(--spacing-3); }
.mt-4 { margin-top: var(--spacing-4); }

/* Text */
.text-red {
  color: var(--color-error);
}

.text-center {
  text-align: center;
}

.text-sm {
  font-size: var(--font-size-sm);
}

/* Width */
.width-full {
  width: 100%;
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: var(--spacing-8);
  color: var(--color-text-muted);
  font-size: var(--font-size-lg);
  background: var(--color-surface);
  border-radius: 16px;
  border: 2px dashed var(--color-border);
}

/* =================================
   Button Component
   ================================= */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-2) var(--spacing-4);
  border-radius: 8px;
  border: none;
  cursor: pointer;
  font-family: inherit;
  font-weight: 600;
  font-size: var(--font-size-base);
  transition: all var(--transition-fast);
  text-decoration: none;
}

.btn-primary {
  background: var(--gradient-primary);
  color: white;
  box-shadow: 0 8px 24px rgba(99, 102, 241, 0.3);
  border-radius: 16px;
  font-weight: 700;
  padding: 14px 32px;
}

.btn-primary:hover {
  transform: translateY(-3px) scale(1.02);
  box-shadow: 0 16px 40px rgba(99, 102, 241, 0.45);
}

.btn-primary:active {
  transform: translateY(-1px) scale(1.01);
  box-shadow: 0 8px 20px rgba(99, 102, 241, 0.35);
}

.btn-secondary {
  background-color: transparent;
  border: 2px solid var(--color-text-secondary);
  color: var(--color-text-primary);
}

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

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

.btn-danger:hover {
  opacity: 0.9;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* =================================
   Form Styles
   ================================= */
.form-group {
  margin-bottom: var(--spacing-3);
}

.form-control {
  width: 100%;
  padding: 16px 20px;
  border: 2px solid var(--color-border);
  border-radius: 16px;
  font-family: inherit;
  font-size: var(--font-size-base);
  color: var(--color-text-primary);
  background: var(--color-surface);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.form-control:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 5px rgba(99, 102, 241, 0.12), 0 4px 16px rgba(99, 102, 241, 0.1);
  transform: translateY(-2px);
}

.is-invalid {
  border-color: var(--color-error) !important;
}

.is-invalid:focus {
  box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.1) !important;
}

/* =================================
   Modal Component
   ================================= */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1000;
  animation: fadeIn var(--transition-base);
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

.modal-content {
  background-color: var(--color-surface);
  padding: var(--spacing-8);
  border-radius: 32px;
  max-width: 560px;
  width: 92%;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 32px 80px -16px rgba(0, 0, 0, 0.3);
  animation: slideUp var(--transition-slow);
  border: none;
}

@keyframes slideUp {
  from {
    transform: translateY(20px);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

/* =================================
   Confirm Modal Styles
   ================================= */
.modal-dialog {
  background-color: var(--color-surface);
  padding: var(--spacing-6);
  border-radius: 16px;
  max-width: 480px;
  width: 90%;
  box-shadow: var(--shadow-xl);
  animation: slideUp var(--transition-slow);
  border: 1px solid var(--color-border);
}

.modal-header {
  margin-bottom: var(--spacing-4);
}

.modal-title {
  color: var(--color-text-primary);
  font-size: var(--font-size-2xl);
  font-weight: 700;
  margin: 0;
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
}

.modal-title::before {
  content: '⚠️';
  font-size: var(--font-size-3xl);
}

.modal-body {
  margin-bottom: var(--spacing-5);
  padding: var(--spacing-4);
  background: var(--color-background);
  border-radius: 8px;
  border-left: 4px solid var(--color-warning);
}

.modal-message {
  color: var(--color-text-primary);
  font-size: var(--font-size-lg);
  line-height: 1.6;
  margin: 0;
  font-weight: 500;
}

.modal-footer {
  display: flex;
  gap: var(--spacing-2);
  justify-content: flex-end;
}

.modal-footer .btn {
  padding: var(--spacing-2) var(--spacing-5);
  font-size: var(--font-size-base);
  font-weight: 600;
  border-radius: 8px;
  cursor: pointer;
  transition: all var(--transition-fast);
  border: 2px solid transparent;
}

.modal-footer .btn:not(.btn-danger) {
  background: var(--color-surface);
  border-color: var(--color-border);
  color: var(--color-text-primary);
}

.modal-footer .btn:not(.btn-danger):hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-1px);
}

.modal-footer .btn-danger {
  background: var(--color-error);
  color: white;
  box-shadow: var(--shadow-md);
}

.modal-footer .btn-danger:hover {
  background: #dc2626;
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

/* =================================
   Add/Edit Exam Form Styles
   ================================= */
.add-exam-form h2 {
  color: var(--color-text-primary);
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: var(--spacing-5);
  padding-bottom: var(--spacing-4);
  border-bottom: 3px solid transparent;
  background: linear-gradient(90deg, var(--color-primary) 0%, var(--color-secondary) 100%) left bottom / 120px 3px no-repeat;
  letter-spacing: -0.01em;
}

.add-exam-form label {
  display: block;
  margin-bottom: var(--spacing-1);
  color: var(--color-text-primary);
  font-weight: 600;
  font-size: var(--font-size-sm);
}

.add-exam-form .form-group {
  margin-bottom: var(--spacing-4);
}

.add-exam-form input[type="text"],
.add-exam-form input[type="date"] {
  width: 100%;
  padding: var(--spacing-2) var(--spacing-3);
  border: 2px solid var(--color-border);
  border-radius: 8px;
  font-size: var(--font-size-base);
  color: var(--color-text-primary);
  background: var(--color-surface);
  transition: all var(--transition-fast);
}

.add-exam-form input[type="text"]:focus,
.add-exam-form input[type="date"]:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

/* Date Conflict Warning */
.date-warning {
  padding: var(--spacing-2) var(--spacing-3);
  background: rgba(245, 158, 11, 0.1);
  border-left: 4px solid var(--color-warning);
  border-radius: 6px;
  color: var(--color-text-primary);
  font-size: var(--font-size-sm);
  line-height: 1.5;
}

[data-theme="dark"] .date-warning {
  background: rgba(245, 158, 11, 0.15);
}

/* Urgency Level Section */
.urgency-options {
  display: flex;
  gap: var(--spacing-2);
}

.urgency-option {
  flex: 1;
  padding: 16px 24px;
  border: 2px solid var(--color-border);
  border-radius: 16px;
  background: var(--color-surface);
  color: var(--color-text-primary);
  font-weight: 700;
  font-size: var(--font-size-sm);
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  text-align: center;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.urgency-option:hover {
  border-color: var(--color-primary);
  transform: translateY(-3px) scale(1.02);
  box-shadow: 0 8px 24px rgba(99, 102, 241, 0.15);
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.08) 0%, rgba(139, 92, 246, 0.08) 100%);
}

.urgency-option.selected {
  border-color: transparent;
  background: var(--gradient-primary);
  color: white;
  box-shadow: 0 8px 24px rgba(99, 102, 241, 0.4);
  transform: translateY(-2px) scale(1.03);
}

/* Topics Section in Form */
.add-exam-form h4 {
  color: var(--color-text-primary);
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-top: var(--spacing-3);
  margin-bottom: 4px;
}

.add-exam-form ul {
  list-style: none;
  padding: 0;
  margin-bottom: var(--spacing-2);
  max-height: 200px;
  overflow-y: auto;
}

.add-exam-form li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-2) var(--spacing-3);
  margin-bottom: var(--spacing-1);
  background: linear-gradient(135deg, rgba(139, 92, 246, 0.05) 0%, rgba(168, 85, 247, 0.05) 100%);
  border-radius: 12px;
  border-left: 3px solid var(--color-secondary);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.04);
}

.add-exam-form li:hover {
  background: linear-gradient(135deg, rgba(139, 92, 246, 0.08) 0%, rgba(168, 85, 247, 0.08) 100%);
  transform: translateX(4px);
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.08);
}

.add-exam-form .btn-icon {
  background: transparent;
  border: none;
  color: var(--color-error);
  cursor: pointer;
  font-size: var(--font-size-2xl);
  line-height: 1;
  padding: 0;
  margin-left: var(--spacing-2);
  transition: all var(--transition-fast);
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 4px;
}

.add-exam-form .btn-icon:hover {
  background: var(--color-error);
  color: white;
}

/* Add Topic Section */
.add-exam-form .form-group.d-flex {
  gap: var(--spacing-2);
}

.add-exam-form__add-topic-btn {
  background: var(--gradient-primary);
  color: white;
  border: none;
  padding: 12px 24px;
  border-radius: 12px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-base);
  white-space: nowrap;
  box-shadow: var(--shadow-md);
}

.add-exam-form__add-topic-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(99, 102, 241, 0.3);
}

.add-exam-form__add-topic-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* Form Actions */
.add-exam-form__cancel-btn {
  background: var(--color-border);
  border: 2px solid transparent;
  color: var(--color-text-secondary);
  padding: 16px 32px;
  border-radius: 16px;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.add-exam-form__cancel-btn:hover {
  background: var(--color-divider);
  color: var(--color-text-primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.add-exam-form__save-btn {
  background: var(--gradient-primary);
  color: white;
  border: none;
  padding: 16px 40px;
  border-radius: 16px;
  font-weight: 700;
  font-size: 1.05rem;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 8px 24px rgba(99, 102, 241, 0.3);
}

.add-exam-form__save-btn:hover:not(:disabled) {
  transform: translateY(-3px) scale(1.02);
  box-shadow: 0 16px 40px rgba(99, 102, 241, 0.45);
}

.add-exam-form__save-btn:active:not(:disabled) {
  transform: translateY(-1px) scale(1.01);
  box-shadow: 0 8px 20px rgba(99, 102, 241, 0.35);
}

.add-exam-form__save-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* Error Messages */
.error-message {
  padding: var(--spacing-2) var(--spacing-3);
  background: rgba(239, 68, 68, 0.1);
  border-left: 4px solid var(--color-error);
  border-radius: 6px;
  color: var(--color-error);
  font-size: var(--font-size-sm);
  animation: slideDown var(--transition-base);
}

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

/* =================================
   Responsive Design
   ================================= */
@media (max-width: 768px) {
  .dashboard {
    padding: var(--spacing-4) var(--spacing-2);
  }

  .dashboard header {
    flex-direction: column;
    align-items: stretch;
  }

  .theme-toggle-container {
    justify-content: space-between;
  }

  h1 {
    font-size: var(--font-size-3xl);
  }

  .exam-card {
    padding: var(--spacing-3);
  }

  .exam-card__title {
    font-size: var(--font-size-xl);
  }

  .exam-card__actions {
    flex-direction: column;
  }
}

@media (max-width: 480px) {
  h1 {
    font-size: var(--font-size-2xl);
  }

  .exam-card__meta {
    flex-direction: column;
    gap: var(--spacing-2);
  }
}

/* =================================
   Loading Spinner
   ================================= */
.loading-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 400px;
  gap: var(--spacing-3);
}

.loading-spinner {
  width: 48px;
  height: 48px;
  border: 4px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.loading-text {
  color: var(--color-text-secondary);
  font-size: var(--font-size-lg);
  font-weight: 500;
}