:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --bg: #ffffff;
  --bg-secondary: #f8fafc;
  --card: #ffffff;
  --text: #0f172a;
  --text-secondary: #64748b;
  --border: #e2e8f0;
  --shadow: 0 1px 3px rgba(0,0,0,0.1);
  --radius: 12px;
}
[data-theme="dark"] {
  --primary: #818cf8;
  --primary-dark: #6366f1;
  --bg: #0f172a;
  --bg-secondary: #1e293b;
  --card: #1e293b;
  --text: #f1f5f9;
  --text-secondary: #94a3b8;
  --border: #334155;
  --shadow: 0 1px 3px rgba(0,0,0,0.4);
}
*, *::before, *::after { margin:0; padding:0; box-sizing:border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: background 0.3s, color 0.3s;
}
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* Header */
.header {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 100;
  backdrop-filter: blur(10px);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 0; gap: 20px;
}
.logo { font-size: 1.5rem; font-weight: 800; color: var(--primary); }
.logo span { color: var(--text); }
.search-box {
  flex: 1; max-width: 400px; position: relative;
}
.search-box input {
  width: 100%; padding: 10px 16px 10px 40px;
  border: 1px solid var(--border); border-radius: 8px;
  background: var(--bg-secondary); color: var(--text);
  font-size: 0.9rem;
}
.search-box input:focus { outline: none; border-color: var(--primary); }
.search-icon { position: absolute; left: 12px; top: 50%; transform: translateY(-50%); color: var(--text-secondary); }
.theme-toggle {
  background: none; border: 1px solid var(--border);
  padding: 8px 12px; border-radius: 8px; cursor: pointer;
  color: var(--text); font-size: 1.2rem;
}

/* Categories */
.categories-bar {
  display: flex; gap: 8px; overflow-x: auto; padding: 16px 0;
  -webkit-overflow-scrolling: touch;
}
.cat-btn {
  white-space: nowrap; padding: 8px 20px;
  background: var(--bg-secondary); border: 1px solid var(--border);
  border-radius: 20px; color: var(--text-secondary); cursor: pointer;
  font-weight: 500; transition: all 0.2s; font-size: 0.9rem;
}
.cat-btn:hover, .cat-btn.active { background: var(--primary); color: #fff; border-color: var(--primary); }

/* Hero */
.hero {
  text-align: center; padding: 60px 0 40px;
}
.hero h1 { font-size: 2.5rem; font-weight: 800; margin-bottom: 12px; }
.hero h1 span { color: var(--primary); }
.hero p { color: var(--text-secondary); font-size: 1.1rem; max-width: 600px; margin: 0 auto; }

/* Tools Grid */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px; padding-bottom: 60px;
}
.tool-card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px;
  transition: all 0.2s; cursor: pointer;
  box-shadow: var(--shadow);
}
.tool-card:hover {
  transform: translateY(-2px); box-shadow: 0 4px 12px rgba(99,102,241,0.15);
  border-color: var(--primary);
}
.tool-icon { font-size: 2rem; margin-bottom: 12px; }
.tool-card h3 { font-size: 1.1rem; margin-bottom: 4px; }
.tool-card p { color: var(--text-secondary); font-size: 0.85rem; }

/* Tool Page */
.tool-page { padding: 32px 0 60px; }
.tool-header { margin-bottom: 24px; }
.tool-header h1 { font-size: 2rem; font-weight: 700; margin-bottom: 8px; }
.tool-header p { color: var(--text-secondary); }
.tool-box {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 32px;
  box-shadow: var(--shadow); max-width: 600px; margin-bottom: 32px;
}
.form-group { margin-bottom: 16px; }
.form-group label { display: block; font-weight: 600; margin-bottom: 6px; font-size: 0.9rem; }
.form-group input, .form-group select, .form-group textarea {
  width: 100%; padding: 10px 14px;
  border: 1px solid var(--border); border-radius: 8px;
  background: var(--bg); color: var(--text); font-size: 1rem;
}
.form-group input:focus, .form-group select:focus, .form-group textarea:focus {
  outline: none; border-color: var(--primary);
}
.form-group textarea { min-height: 100px; resize: vertical; font-family: monospace; }
.btn {
  padding: 12px 24px; background: var(--primary); color: #fff;
  border: none; border-radius: 8px; cursor: pointer; font-weight: 600;
  font-size: 1rem; transition: background 0.2s;
}
.btn:hover { background: var(--primary-dark); }
.btn-block { width: 100%; }
.result-box {
  background: var(--bg-secondary); border: 1px solid var(--border);
  border-radius: 8px; padding: 16px; margin-top: 16px;
  font-size: 1.1rem; font-weight: 600; text-align: center;
}
.result-box .value { color: var(--primary); font-size: 1.5rem; }
.result-box .label { color: var(--text-secondary); font-size: 0.85rem; font-weight: 400; }
.result-box .desc { font-size: 0.9rem; font-weight: 400; color: var(--text-secondary); margin-top: 4px; }

/* Article / SEO */
.article { max-width: 800px; margin: 40px auto; }
.article h2 { font-size: 1.5rem; margin: 24px 0 12px; }
.article p { color: var(--text-secondary); margin-bottom: 12px; }
.article ul { color: var(--text-secondary); padding-left: 20px; margin-bottom: 12px; }
.article ul li { margin-bottom: 6px; }

/* Footer */
.footer {
  border-top: 1px solid var(--border); padding: 32px 0;
  text-align: center; color: var(--text-secondary); font-size: 0.85rem;
}

/* Breadcrumb */
.breadcrumb { display: flex; gap: 8px; margin-bottom: 16px; font-size: 0.85rem; color: var(--text-secondary); }
.breadcrumb a { color: var(--text-secondary); }
.breadcrumb a:hover { color: var(--primary); }

/* Responsive */
@media (max-width: 768px) {
  .hero h1 { font-size: 1.8rem; }
  .hero p { font-size: 1rem; }
  .tools-grid { grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); }
  .tool-box { padding: 20px; }
  .header-inner { flex-wrap: wrap; }
  .search-box { order: 3; flex: 100%; max-width: 100%; }
}
@media (max-width: 480px) {
  .tools-grid { grid-template-columns: 1fr; }
}

/* Row for multi-column forms */
.row { display: flex; gap: 12px; }
.row .form-group { flex: 1; }

/* Copy button */
.copy-btn {
  background: var(--bg-secondary); border: 1px solid var(--border);
  padding: 8px 16px; border-radius: 6px; cursor: pointer;
  color: var(--text); font-size: 0.85rem; margin-top: 8px;
}
.copy-btn:hover { border-color: var(--primary); color: var(--primary); }

/* Output area */
.output-box {
  background: var(--bg-secondary); border: 1px solid var(--border);
  border-radius: 8px; padding: 16px; margin-top: 16px;
  font-family: monospace; white-space: pre-wrap; word-break: break-all;
  font-size: 0.9rem; min-height: 50px;
}

/* Tool page description */
.tool-desc { margin-bottom: 24px; color: var(--text-secondary); }

/* Filter / sort */
.filter-bar { display: flex; gap: 8px; margin-bottom: 24px; flex-wrap: wrap; }
.filter-btn {
  padding: 6px 16px; border: 1px solid var(--border);
  border-radius: 16px; background: var(--bg); color: var(--text-secondary);
  cursor: pointer; font-size: 0.8rem; transition: all 0.2s;
}
.filter-btn:hover, .filter-btn.active { background: var(--primary); color: #fff; border-color: var(--primary); }

/* Ad placeholder */
.ad-placeholder {
  background: var(--bg-secondary); border: 1px solid var(--border);
  border-radius: 8px; padding: 60px 20px; text-align: center;
  color: var(--text-secondary); font-size: 0.85rem; margin: 16px 0;
}