:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f0f2f5;
  --bg-sidebar: #1a1d23;
  --bg-sidebar-hover: #2a2d35;
  --bg-card: #ffffff;
  --bg-input: #f7f8fa;
  --text-primary: #1a1d23;
  --text-secondary: #5f6368;
  --text-sidebar: #e8eaed;
  --text-sidebar-dim: #9aa0a6;
  --border-color: #dadce0;
  --accent: #4f6ef7;
  --accent-hover: #3b5de7;
  --accent-light: #e8ecff;
  --success: #34a853;
  --danger: #ea4335;
  --warning: #fbbc04;
  --shadow: 0 1px 3px rgba(0,0,0,0.1);
  --shadow-lg: 0 4px 12px rgba(0,0,0,0.12);
  --radius: 10px;
  --radius-sm: 6px;
  --sidebar-width: 280px;
  --topbar-height: 60px;
  --transition: 0.25s ease;
}
[data-theme="dark"] {
  --bg-primary: #1a1d23;
  --bg-secondary: #22252b;
  --bg-sidebar: #121418;
  --bg-sidebar-hover: #1e2028;
  --bg-card: #262930;
  --bg-input: #2d3038;
  --text-primary: #e8eaed;
  --text-secondary: #9aa0a6;
  --text-sidebar: #e8eaed;
  --text-sidebar-dim: #6b7280;
  --border-color: #3a3d45;
  --accent-light: #1e2440;
  --shadow: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-lg: 0 4px 12px rgba(0,0,0,0.4);
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, sans-serif;
  background: var(--bg-secondary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}
a { color: var(--accent); text-decoration: none; }
button { cursor: pointer; font-family: inherit; border: none; background: none; }
input, textarea, select {
  font-family: inherit;
  font-size: 0.9rem;
  padding: 10px 14px;
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-sm);
  background: var(--bg-input);
  color: var(--text-primary);
  transition: border-color var(--transition);
  width: 100%;
}
input:focus, textarea:focus, select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-light);
}
textarea { resize: vertical; min-height: 120px; }

#app { display: flex; min-height: 100vh; }

.sidebar {
  position: fixed;
  top: 0; left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  background: var(--bg-sidebar);
  color: var(--text-sidebar);
  display: flex;
  flex-direction: column;
  z-index: 1000;
  transform: translateX(0);
  transition: transform var(--transition);
  overflow: hidden;
}
.sidebar.closed { transform: translateX(-100%); }
.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid rgba(255,255,255,0.08);
}
.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text-sidebar) !important;
  font-size: 1.2rem;
  font-weight: 700;
}
.logo-icon { font-size: 1.5rem; }
.sidebar-close {
  color: var(--text-sidebar-dim);
  font-size: 1.5rem;
  padding: 4px;
  display: none;
}
.sidebar-search {
  position: relative;
  padding: 12px 16px;
}
.sidebar-search input {
  background: var(--bg-sidebar-hover);
  border-color: transparent;
  color: var(--text-sidebar);
  padding-left: 36px;
}
.sidebar-search input::placeholder { color: var(--text-sidebar-dim); }
.sidebar-search input:focus { border-color: var(--accent); }
.search-icon {
  position: absolute;
  left: 26px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-sidebar-dim);
  font-size: 0.85rem;
}
.sidebar-nav {
  flex: 1;
  overflow-y: auto;
  padding: 8px 0 20px;
}
.sidebar-nav::-webkit-scrollbar { width: 4px; }
.sidebar-nav::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.15); border-radius: 2px; }
.nav-category { padding: 0 16px; }
.nav-category-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 12px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-sidebar-dim);
  cursor: pointer;
  user-select: none;
  border-radius: var(--radius-sm);
  transition: background var(--transition);
}
.nav-category-header:hover { background: var(--bg-sidebar-hover); }
.nav-category-header .arrow {
  margin-left: auto;
  font-size: 0.7rem;
  transition: transform var(--transition);
}
.nav-category-header .arrow.open { transform: rotate(90deg); }
.nav-items { overflow: hidden; max-height: 0; transition: max-height 0.3s ease; }
.nav-items.open { max-height: 1000px; }
.nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px 8px 28px;
  font-size: 0.88rem;
  color: var(--text-sidebar);
  border-radius: var(--radius-sm);
  transition: background var(--transition);
  text-decoration: none;
}
.nav-item:hover { background: var(--bg-sidebar-hover); }
.nav-item.active { background: var(--accent); color: #fff; }
.nav-item .nav-icon { font-size: 1rem; width: 20px; text-align: center; }

.sidebar-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 999;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition);
}
.sidebar-overlay.visible { opacity: 1; pointer-events: auto; }

.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  transition: margin-left var(--transition);
}
.sidebar.closed ~ .main-content,
.sidebar.closed + .sidebar-overlay + .main-content { margin-left: 0; }

.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--topbar-height);
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 24px;
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow);
}
.menu-btn {
  font-size: 1.3rem;
  color: var(--text-primary);
  padding: 8px;
  border-radius: var(--radius-sm);
  display: none;
}
.menu-btn:hover { background: var(--bg-secondary); }
.page-title {
  font-size: 1.15rem;
  font-weight: 600;
  flex: 1;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.topbar-actions { display: flex; gap: 8px; }
.icon-btn {
  width: 38px;
  height: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 1.2rem;
  transition: background var(--transition);
}
.icon-btn:hover { background: var(--bg-secondary); }

.content-area {
  flex: 1;
  padding: 24px;
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
}

/* Homepage */
.homepage { padding: 0 0 40px; }
.homepage-header {
  text-align: center;
  padding: 40px 20px 32px;
}
.homepage-header h1 { font-size: 2rem; font-weight: 700; margin-bottom: 8px; }
.homepage-header p { color: var(--text-secondary); font-size: 1.05rem; max-width: 600px; margin: 0 auto; }
.homepage-stats {
  display: flex;
  justify-content: center;
  gap: 40px;
  margin-top: 20px;
  flex-wrap: wrap;
}
.stat { text-align: center; }
.stat-number { font-size: 1.8rem; font-weight: 700; color: var(--accent); }
.stat-label { font-size: 0.85rem; color: var(--text-secondary); }

.homepage-categories {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 20px;
  margin-top: 8px;
}
.homepage-category {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border-color);
}
.homepage-category h2 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.homepage-category .category-icon { font-size: 1.2rem; }
.homepage-category .tool-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 6px;
}
.homepage-category .tool-link {
  display: block;
  padding: 8px 10px;
  font-size: 0.85rem;
  color: var(--text-primary);
  background: var(--bg-secondary);
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}
.homepage-category .tool-link:hover {
  background: var(--accent-light);
  color: var(--accent);
}

/* Tool page container */
.tool-page { padding: 0 0 40px; }
.tool-page-header { margin-bottom: 24px; }
.tool-page-header h2 { font-size: 1.5rem; font-weight: 600; }
.tool-page-header p { color: var(--text-secondary); font-size: 0.95rem; margin-top: 4px; }

.tool-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  margin-bottom: 20px;
}
.tool-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.form-row {
  display: flex;
  gap: 12px;
  margin-bottom: 12px;
  flex-wrap: wrap;
}
.form-row > * { flex: 1; min-width: 140px; }
.form-group { margin-bottom: 14px; }
.form-group label {
  display: block;
  font-size: 0.85rem;
  font-weight: 500;
  margin-bottom: 4px;
  color: var(--text-secondary);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  font-size: 0.9rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
  border: 1.5px solid transparent;
}
.btn-primary {
  background: var(--accent);
  color: #fff;
}
.btn-primary:hover { background: var(--accent-hover); }
.btn-success {
  background: var(--success);
  color: #fff;
}
.btn-success:hover { opacity: 0.9; }
.btn-danger {
  background: var(--danger);
  color: #fff;
}
.btn-danger:hover { opacity: 0.9; }
.btn-outline {
  background: transparent;
  border-color: var(--border-color);
  color: var(--text-primary);
}
.btn-outline:hover { background: var(--bg-secondary); }
.btn-sm { padding: 6px 14px; font-size: 0.82rem; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

.output-area {
  margin-top: 16px;
  padding: 16px;
  background: var(--bg-secondary);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  min-height: 40px;
  white-space: pre-wrap;
  word-break: break-word;
  font-size: 0.9rem;
  position: relative;
}
.output-area .copy-btn {
  position: absolute;
  top: 8px;
  right: 8px;
}
.copy-btn {
  padding: 4px 10px;
  font-size: 0.75rem;
  background: var(--accent);
  color: #fff;
  border-radius: 4px;
  opacity: 0.7;
  transition: opacity var(--transition);
}
.copy-btn:hover { opacity: 1; }

.file-drop {
  border: 2px dashed var(--border-color);
  border-radius: var(--radius);
  padding: 40px 20px;
  text-align: center;
  transition: all var(--transition);
  cursor: pointer;
}
.file-drop:hover, .file-drop.dragover {
  border-color: var(--accent);
  background: var(--accent-light);
}
.file-drop-icon { font-size: 2.5rem; margin-bottom: 8px; }
.file-drop-text { color: var(--text-secondary); font-size: 0.9rem; }
.file-drop-text strong { color: var(--accent); }

.upload-preview {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 12px;
}
.upload-preview img {
  max-width: 120px;
  max-height: 120px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  object-fit: cover;
}

.alert {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  margin-bottom: 12px;
  font-size: 0.9rem;
}
.alert-success { background: #d4edda; color: #155724; border: 1px solid #c3e6cb; }
.alert-error { background: #f8d7da; color: #721c24; border: 1px solid #f5c6cb; }
.alert-info { background: #d1ecf1; color: #0c5460; border: 1px solid #bee5eb; }

[data-theme="dark"] .alert-success { background: #1e3a1e; color: #8bc34a; border-color: #2e5a2e; }
[data-theme="dark"] .alert-error { background: #3a1e1e; color: #ef9a9a; border-color: #5a2e2e; }
[data-theme="dark"] .alert-info { background: #1e2a3a; color: #81d4fa; border-color: #2e3a5a; }

.range-group { display: flex; align-items: center; gap: 12px; }
.range-group input[type="range"] { flex: 1; padding: 0; border: none; background: none; }
.range-value { min-width: 50px; text-align: center; font-weight: 600; }

.tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 16px;
  border-bottom: 2px solid var(--border-color);
  padding-bottom: 0;
  flex-wrap: wrap;
}
.tab {
  padding: 10px 20px;
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--text-secondary);
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: all var(--transition);
}
.tab:hover { color: var(--text-primary); }
.tab.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

@media (max-width: 768px) {
  .sidebar { transform: translateX(-100%); }
  .sidebar.open { transform: translateX(0); }
  .sidebar-close { display: block; }
  .menu-btn { display: block; }
  .main-content { margin-left: 0 !important; }
  .content-area { padding: 16px; }
  .homepage-categories { grid-template-columns: 1fr; }
  .homepage-category .tool-list { grid-template-columns: 1fr; }
  .form-row > * { min-width: 100%; }
  .homepage-header h1 { font-size: 1.5rem; }
  .stat-number { font-size: 1.4rem; }
}

@media (min-width: 769px) {
  .sidebar.closed { transform: translateX(-100%); }
}