@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

:root {
  --bg-primary: #f9fafb;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f3f4f6;
  --glass-bg: #ffffff;
  --glass-border: #e5e7eb;
  --accent-color: #2563eb;
  --accent-hover: #1d4ed8;
  --text-primary: #111827;
  --text-secondary: #4b5563;
  --text-muted: #9ca3af;
  --success: #10b981;
  --error: #ef4444;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --radius: 8px;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

[data-theme="dark"] {
  --bg-primary: #0b0f19;
  --bg-secondary: #111827;
  --bg-tertiary: #1f2937;
  --glass-bg: #111827;
  --glass-border: #1f2937;
  --accent-color: #3b82f6;
  --accent-hover: #2563eb;
  --text-primary: #f3f4f6;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;
  --success: #10b981;
  --error: #ef4444;
  --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg-primary: #0b0f19;
    --bg-secondary: #111827;
    --bg-tertiary: #1f2937;
    --glass-bg: #111827;
    --glass-border: #1f2937;
    --accent-color: #3b82f6;
    --accent-hover: #2563eb;
    --text-primary: #f3f4f6;
    --text-secondary: #9ca3af;
    --text-muted: #6b7280;
    --success: #10b981;
    --error: #ef4444;
    --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
  }
}

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

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font);
  line-height: 1.6;
  min-height: 100vh;
  transition: background-color 0.2s ease, color 0.2s ease;
  display: flex;
  flex-direction: column;
}

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

header {
  background: var(--glass-bg);
  border-bottom: 1px solid var(--glass-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-container {
  align-items: center;
  display: flex;
  justify-content: space-between;
  margin: 0 auto;
  max-width: 1200px;
  padding: 1rem 2rem;
  gap: 1.5rem;
}

.logo-link {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}

.logo-link img {
  height: 40px;
  width: auto;
}

.search-bar {
  position: relative;
  flex-grow: 1;
  max-width: 450px;
}

.search-bar input {
  background: var(--bg-tertiary);
  border: 1px solid var(--glass-border);
  border-radius: 20px;
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 0.9rem;
  padding: 0.6rem 1rem 0.6rem 2.5rem;
  transition: all 0.3s ease;
  width: 100%;
}

.search-bar input:focus {
  border-color: var(--accent-color);
  outline: none;
}

.search-icon {
  color: var(--text-muted);
  left: 1rem;
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-shrink: 0;
}

.theme-selector select {
  background: var(--bg-tertiary);
  border: 1px solid var(--glass-border);
  border-radius: 6px;
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 0.85rem;
  padding: 0.5rem 1rem;
  cursor: pointer;
}

.theme-selector select:focus {
  border-color: var(--accent-color);
  outline: none;
}

.btn {
  align-items: center;
  background: var(--accent-color);
  border: none;
  border-radius: 20px;
  color: #fff;
  cursor: pointer;
  display: inline-flex;
  font-family: var(--font);
  font-weight: 500;
  gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  transition: background-color 0.2s ease, transform 0.1s ease;
}

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

.btn-secondary {
  background: var(--bg-tertiary);
  border: 1px solid var(--glass-border);
  color: var(--text-primary);
}

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

.main-layout {
  display: grid;
  gap: 2rem;
  grid-template-columns: 240px 1fr;
  margin: 2rem auto;
  max-width: 1200px;
  padding: 0 2rem;
  flex: 1;
  width: 100%;
}

.sidebar {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.sidebar-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.sidebar-title {
  color: var(--text-secondary);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  margin-bottom: 1rem;
  text-transform: uppercase;
}

.category-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  list-style: none;
}

.category-item button {
  align-items: center;
  background: none;
  border: none;
  border-radius: 8px;
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  font-family: var(--font);
  font-size: 0.9rem;
  gap: 0.8rem;
  padding: 0.5rem 0.8rem;
  transition: all 0.2s ease;
  width: 100%;
}

.category-item button:hover, .category-item.active button {
  background: var(--bg-tertiary);
  color: var(--accent-color);
}

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

.feed-filters {
  display: flex;
  gap: 0.5rem;
}

.filter-btn {
  background: var(--bg-secondary);
  border: 1px solid var(--glass-border);
  border-radius: 8px;
  color: var(--text-secondary);
  cursor: pointer;
  font-family: var(--font);
  font-size: 0.85rem;
  padding: 0.4rem 0.8rem;
  transition: all 0.2s ease;
}

.filter-btn.active, .filter-btn:hover {
  background: var(--accent-color);
  border-color: var(--accent-color);
  color: #fff;
}

.question-list {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.question-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  display: flex;
  gap: 1.5rem;
  padding: 1.5rem;
  transition: border-color 0.3s ease;
}

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

.vote-control {
  align-items: center;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.vote-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 1.2rem;
  transition: color 0.2s ease;
}

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

.vote-btn.active-up {
  color: var(--success);
}

.vote-btn.active-down {
  color: var(--error);
}

.vote-count {
  font-weight: 600;
  font-size: 1rem;
}

.question-content {
  flex: 1;
}

.question-meta {
  align-items: center;
  color: var(--text-muted);
  display: flex;
  font-size: 0.85rem;
  gap: 0.8rem;
  margin-bottom: 0.5rem;
}

.author-name {
  color: var(--text-secondary);
  font-weight: 500;
}

.question-title {
  color: var(--text-primary);
  cursor: pointer;
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  transition: color 0.2s ease;
}

.question-title:hover {
  color: var(--accent-color);
}

.question-body {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 1rem;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tag {
  background: var(--bg-tertiary);
  border: 1px solid var(--glass-border);
  border-radius: 4px;
  color: var(--accent-color);
  font-size: 0.8rem;
  font-weight: 500;
  padding: 0.2rem 0.5rem;
}

.question-stats {
  align-items: center;
  border-top: 1px solid var(--glass-border);
  color: var(--text-muted);
  display: flex;
  gap: 1.5rem;
  margin-top: 1rem;
  padding-top: 1rem;
}

.stat-item {
  align-items: center;
  display: flex;
  gap: 0.4rem;
  font-size: 0.85rem;
}

.modal {
  align-items: center;
  background: rgba(0, 0, 0, 0.5);
  display: none;
  height: 100%;
  justify-content: center;
  left: 0;
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 200;
}

.modal-content {
  background: var(--bg-secondary);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  max-height: 85vh;
  max-width: 600px;
  padding: 2rem;
  position: relative;
  width: 90%;
}

.close-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 1.5rem;
  position: absolute;
  right: 1.5rem;
  top: 1.5rem;
  transition: color 0.2s ease;
}

.close-btn:hover {
  color: var(--text-primary);
}

.modal-header {
  margin-bottom: 1.5rem;
}

.form-group {
  margin-bottom: 1.25rem;
}

.form-group label {
  color: var(--text-secondary);
  display: block;
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 0.5rem;
}

.form-group input, .form-group textarea, .form-group select {
  background: var(--bg-tertiary);
  border: 1px solid var(--glass-border);
  border-radius: 8px;
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 0.95rem;
  padding: 0.75rem;
  transition: all 0.3s ease;
  width: 100%;
}

.form-group input:focus, .form-group textarea:focus, .form-group select:focus {
  border-color: var(--accent-color);
  outline: none;
}

.form-actions {
  display: flex;
  justify-content: flex-end;
  gap: 1rem;
  margin-top: 1.5rem;
}

.detail-answers {
  border-top: 1px solid var(--glass-border);
  margin-top: 2rem;
  padding-top: 1.5rem;
}

.answers-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
}

.answer-card {
  background: var(--bg-tertiary);
  border: 1px solid var(--glass-border);
  border-radius: 8px;
  margin-bottom: 1rem;
  padding: 1.2rem;
}

.answer-meta {
  color: var(--text-muted);
  font-size: 0.8rem;
  margin-bottom: 0.5rem;
}

.answer-author {
  color: var(--text-secondary);
  font-weight: 500;
}

.answer-body {
  color: var(--text-primary);
  font-size: 0.9rem;
}

.add-answer-form {
  margin-top: 2rem;
}

.modal-footer-link {
  text-align: center;
  margin-top: 1rem;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.modal-footer-link a {
  color: var(--accent-color);
  font-weight: 600;
}

.modal-footer-link a:hover {
  text-decoration: underline;
}

footer {
  border-top: 1px solid var(--glass-border);
  color: var(--text-muted);
  margin-top: 4rem;
  padding: 2rem 0;
  text-align: center;
}

@media (max-width: 768px) {
  .main-layout {
    grid-template-columns: 1fr;
  }
  .sidebar {
    display: none;
  }
  .header-container {
    flex-wrap: wrap;
  }
  .search-bar {
    order: 3;
    width: 100%;
    max-width: 100%;
  }
}