/* Modern Dark Theme Variables */
:root {
  --bg: #0f1724;
  --card: #1a2332;
  --card-hover: #1f2937;
  --text: #e6eef8;
  --muted: #9fb0c9;
  --accent: #7dd3fc;
  --accent-hover: #38bdf8;
  --border: rgba(255, 255, 255, 0.08);
  --shadow: rgba(0, 0, 0, 0.3);
  --success: #10b981;
  --warning: #f59e0b;
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
  color: var(--text);
  background: linear-gradient(180deg, #071127 0%, #0a1628 50%, #0f1724 100%);
  min-height: 100vh;
  overflow-x: hidden;
}

/* Container */
.wrap {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.5rem;
}

/* Header */
.site-header {
  background: rgba(15, 23, 36, 0.95);
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(10px);
}

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

.site-header h1 {
  margin: 0;
  font-size: 1.5rem;
  font-weight: 700;
}

.site-header h1 a {
  color: var(--text);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: color 0.3s ease;
}

.site-header h1 a:hover {
  color: var(--accent);
}

.site-header h1 i {
  color: var(--accent);
}

/* Bookmark Toggle Button */
.bookmark-toggle {
  background: var(--card);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.5rem 1rem;
  border-radius: 8px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1rem;
  transition: all 0.3s ease;
  position: relative;
}

.bookmark-toggle:hover {
  background: var(--card-hover);
  border-color: var(--accent);
  transform: translateY(-2px);
}

.bookmark-count {
  background: var(--accent);
  color: var(--bg);
  padding: 0.125rem 0.5rem;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 700;
  min-width: 20px;
  text-align: center;
}

/* Bookmark Panel */
.bookmark-panel {
  position: fixed;
  top: 0;
  right: -400px;
  width: 100%;
  max-width: 400px;
  height: 100vh;
  background: var(--card);
  border-left: 1px solid var(--border);
  z-index: 1000;
  overflow-y: auto;
  transition: right 0.3s ease;
  box-shadow: -4px 0 20px var(--shadow);
}

.bookmark-panel.active {
  right: 0;
}

.bookmark-panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.5rem;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--card);
  z-index: 10;
}

.bookmark-panel-header h2 {
  font-size: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.close-panel {
  background: transparent;
  border: none;
  color: var(--text);
  font-size: 1.5rem;
  cursor: pointer;
  padding: 0.5rem;
  transition: color 0.3s ease;
}

.close-panel:hover {
  color: var(--accent);
}

.bookmark-list {
  padding: 1rem;
}

.empty-bookmarks {
  color: var(--muted);
  text-align: center;
  padding: 2rem;
  font-style: italic;
}

.bookmark-item {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  margin-bottom: 0.75rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: all 0.3s ease;
}

.bookmark-item:hover {
  border-color: var(--accent);
  transform: translateX(-4px);
}

.bookmark-item a {
  color: var(--accent);
  text-decoration: none;
  flex: 1;
  font-weight: 500;
}

.bookmark-item a:hover {
  color: var(--accent-hover);
}

.remove-bookmark {
  background: transparent;
  border: none;
  color: var(--muted);
  cursor: pointer;
  padding: 0.25rem 0.5rem;
  font-size: 1rem;
  transition: color 0.3s ease;
}

.remove-bookmark:hover {
  color: #ef4444;
}

/* Search and Filter */
.search-container {
  margin: 2rem 0;
  position: relative;
}

.search-input {
  width: 100%;
  padding: 1rem 1rem 1rem 3rem;
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: 12px;
  color: var(--text);
  font-size: 1rem;
  transition: all 0.3s ease;
}

.search-input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(125, 211, 252, 0.1);
}

.search-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--muted);
  pointer-events: none;
}

/* Filter Tabs */
.filter-tabs {
  display: flex;
  gap: 0.5rem;
  margin: 1.5rem 0;
  flex-wrap: wrap;
}

.filter-tab {
  background: var(--card);
  border: 2px solid var(--border);
  color: var(--text);
  padding: 0.5rem 1rem;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.9rem;
  transition: all 0.3s ease;
  white-space: nowrap;
}

.filter-tab:hover {
  border-color: var(--accent);
}

.filter-tab.active {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
  font-weight: 600;
}

/* Question Grid */
.questions-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.question-card {
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  transition: all 0.3s ease;
  position: relative;
  display: flex;
  flex-direction: column;
  cursor: pointer;
}

.question-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
  box-shadow: 0 8px 24px var(--shadow);
}

.question-number {
  display: inline-block;
  background: var(--accent);
  color: var(--bg);
  padding: 0.25rem 0.75rem;
  border-radius: 6px;
  font-size: 0.75rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.question-title {
  color: var(--text);
  font-size: 1rem;
  line-height: 1.5;
  margin-bottom: 1rem;
  flex: 1;
}

.question-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
}

.question-unit {
  color: var(--muted);
  font-size: 0.85rem;
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.bookmark-btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--muted);
  padding: 0.4rem 0.8rem;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.9rem;
  transition: all 0.3s ease;
}

.bookmark-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.bookmark-btn.bookmarked {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
}

/* Hero Section */
.hero-section {
  text-align: center;
  padding: 3rem 0 2rem;
  margin-bottom: 2rem;
}

.hero-section h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, var(--accent) 0%, #38bdf8 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  display: inline-block;
}

.hero-section i {
  color: var(--accent);
}

/* Content Styles */
.content {
  margin: 2rem auto;
}

.content h1,
.content h2,
.content h3,
.content h4 {
  color: var(--text);
  margin-top: 2rem;
  margin-bottom: 1rem;
  font-weight: 700;
}

.content h1 {
  font-size: 2.5rem;
  border-bottom: 2px solid var(--accent);
  padding-bottom: 0.5rem;
}

.content h2 {
  font-size: 2rem;
}

.content h3 {
  font-size: 1.5rem;
}

.content p {
  margin-bottom: 1rem;
  color: var(--muted);
}

.content a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.3s ease;
}

.content a:hover {
  color: var(--accent-hover);
  text-decoration: underline;
}

.content ul,
.content ol {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}

.content li {
  margin-bottom: 0.5rem;
  color: var(--muted);
}

.content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  background: var(--card);
  border-radius: 8px;
  overflow: hidden;
}

.content th,
.content td {
  padding: 1rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.content th {
  background: rgba(125, 211, 252, 0.1);
  color: var(--accent);
  font-weight: 600;
}

.content tr:hover {
  background: var(--card-hover);
}

.content pre {
  background: #020617;
  padding: 1.5rem;
  border-radius: 8px;
  overflow-x: auto;
  margin: 1rem 0;
  border: 1px solid var(--border);
}

.content code {
  background: rgba(125, 211, 252, 0.1);
  color: var(--accent);
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  font-family: 'Courier New', monospace;
  font-size: 0.9em;
}

.content pre code {
  background: transparent;
  padding: 0;
  color: #dbeafe;
}

.content blockquote {
  border-left: 4px solid var(--accent);
  padding-left: 1rem;
  margin: 1rem 0;
  color: var(--muted);
  font-style: italic;
}

.content hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 2rem 0;
}

/* Back Button */
.back-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--card);
  color: var(--text);
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  text-decoration: none;
  border: 2px solid var(--border);
  transition: all 0.3s ease;
  margin-bottom: 1.5rem;
}

.back-btn:hover {
  border-color: var(--accent);
  transform: translateX(-4px);
}

/* Page Bookmark Button */
.page-bookmark-btn {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background: var(--accent);
  color: var(--bg);
  width: 56px;
  height: 56px;
  border-radius: 50%;
  border: none;
  cursor: pointer;
  font-size: 1.5rem;
  box-shadow: 0 4px 12px var(--shadow);
  transition: all 0.3s ease;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: center;
}

.page-bookmark-btn:hover {
  transform: scale(1.1);
  box-shadow: 0 6px 20px var(--shadow);
}

.page-bookmark-btn.bookmarked {
  background: var(--success);
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: 0.9rem;
  color: var(--muted);
  padding: 2rem 0;
  margin-top: 4rem;
}

/* Loading Animation */
.loading {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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

/* Mobile Responsive */
@media (max-width: 768px) {
  .wrap {
    padding: 1rem;
  }

  .site-header h1 {
    font-size: 1.25rem;
  }

  .bookmark-toggle {
    padding: 0.4rem 0.75rem;
    font-size: 0.9rem;
  }

  .bookmark-panel {
    max-width: 100%;
    right: -100%;
  }

  .questions-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  .question-card {
    padding: 1.25rem;
  }

  .filter-tabs {
    overflow-x: auto;
    flex-wrap: nowrap;
    padding-bottom: 0.5rem;
  }

  .content h1 {
    font-size: 1.75rem;
  }

  .content h2 {
    font-size: 1.5rem;
  }

  .content h3 {
    font-size: 1.25rem;
  }

  .content table {
    font-size: 0.875rem;
  }

  .content th,
  .content td {
    padding: 0.75rem;
  }

  .page-bookmark-btn {
    bottom: 1rem;
    right: 1rem;
    width: 48px;
    height: 48px;
    font-size: 1.25rem;
  }
}

@media (max-width: 480px) {
  .site-header h1 {
    font-size: 1.1rem;
  }

  .header-content {
    gap: 0.5rem;
  }

  .bookmark-toggle span {
    display: none;
  }

  .question-card {
    padding: 1rem;
  }

  .content {
    font-size: 0.95rem;
  }
}

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

/* Print Styles */
@media print {
  .site-header,
  .bookmark-toggle,
  .bookmark-panel,
  .page-bookmark-btn,
  .site-footer,
  .back-btn {
    display: none;
  }

  body {
    background: white;
    color: black;
  }
}