:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --bg: #f8fafc;
  --card-bg: #ffffff;
  --text: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --border: #e2e8f0;
  --radius: 10px;
  --radius-sm: 6px;
  --shadow: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-hover: 0 4px 12px rgba(0,0,0,0.1);
}

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

html { font-size: 16px; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 20px;
  width: 100%;
}

/* Header */
.site-header {
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  padding: 14px 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

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

.site-title {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--primary);
  text-decoration: none;
  letter-spacing: -0.5px;
}

.site-title:hover {
  color: var(--primary-hover);
}

.lang-switch a {
  font-size: 0.875rem;
  color: var(--text-secondary);
  text-decoration: none;
  padding: 6px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  transition: all 0.2s;
}

.lang-switch a:hover {
  color: var(--primary);
  border-color: var(--primary);
}

/* Breadcrumb */
.breadcrumb {
  padding: 16px 20px;
  font-size: 0.875rem;
  color: var(--text-muted);
}

.breadcrumb a {
  color: var(--text-secondary);
  text-decoration: none;
}

.breadcrumb a:hover {
  color: var(--primary);
}

/* Main Content */
main {
  flex: 1;
  padding-bottom: 40px;
}

h1 {
  font-size: 1.75rem;
  font-weight: 700;
  margin: 24px 0 8px;
  line-height: 1.3;
}

.site-desc, .tool-description {
  color: var(--text-secondary);
  font-size: 1rem;
  margin-bottom: 24px;
  max-width: 720px;
}

/* Ad slot - hidden until AdSense is active */
.ad-slot {
  display: none;
}

/* Tool Grid */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
}

.tool-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  text-decoration: none;
  color: var(--text);
  transition: all 0.2s;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 8px;
  box-shadow: var(--shadow);
}

.tool-card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
}

.tool-icon {
  font-size: 2rem;
  line-height: 1;
}

.tool-name {
  font-weight: 600;
  font-size: 0.95rem;
}

.tool-desc {
  font-size: 0.8rem;
  color: var(--text-muted);
  line-height: 1.4;
}

/* Tool Page */
.tool-page h1 {
  margin-top: 8px;
}

.tool-area {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.tool-input, .tool-output {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  line-height: 1.5;
  resize: vertical;
  transition: border-color 0.2s;
  background: var(--bg);
  color: var(--text);
}

.tool-input:focus, .tool-output:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37,99,235,0.1);
}

.font-mono {
  font-family: "SF Mono", "Fira Code", "Fira Mono", "Menlo", Consolas, monospace;
  font-size: 0.8rem;
}

.tool-output {
  background: #f1f5f9;
  cursor: default;
}

.diff-inputs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 12px;
}

.diff-inputs .tool-input {
  min-height: 200px;
}

.tool-extra, .tool-options {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 12px 0;
  align-items: center;
}

.tool-options label {
  font-size: 0.875rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 4px;
  cursor: pointer;
}

.tool-options input[type="checkbox"] {
  width: 16px;
  height: 16px;
  cursor: pointer;
}

.tool-options input[type="text"], .tool-options input[type="number"] {
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  background: var(--bg);
  color: var(--text);
}

.tool-options select {
  padding: 6px 10px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  background: var(--card-bg);
  color: var(--text);
  cursor: pointer;
}

.inline-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}

.inline-actions .btn {
  flex: 0 0 auto;
  padding: 8px 16px;
  font-size: 0.85rem;
}

.input-sm {
  width: 72px;
  padding: 6px 8px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  text-align: center;
}

/* Buttons */
.tool-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 16px 0;
}

.btn {
  padding: 10px 24px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  background: var(--card-bg);
  color: var(--text);
}

.btn:hover {
  border-color: var(--text-muted);
}

.btn-primary {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

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

.btn-secondary {
  background: var(--card-bg);
  color: var(--text-secondary);
}

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

.btn-clear:hover {
  color: #dc2626;
  border-color: #dc2626;
}

/* Related Tools */
.related-tools {
  margin-top: 40px;
}

.related-tools h2, .faq-section h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 16px;
}

.related-tools .tool-grid {
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
}

.related-tools .tool-card {
  padding: 14px;
}

.related-tools .tool-card .tool-icon {
  font-size: 1.5rem;
}

.related-tools .tool-card .tool-desc {
  display: none;
}

/* Usage Section (SEO) */
.usage-section {
  margin: 16px 0;
  padding: 16px 20px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  line-height: 1.7;
}

.usage-section h2 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.usage-section p {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* FAQ */
.faq-section {
  margin-top: 40px;
}

.faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  margin-bottom: 8px;
  overflow: hidden;
}

.faq-item summary {
  padding: 14px 18px;
  font-weight: 500;
  font-size: 0.925rem;
  cursor: pointer;
  background: var(--card-bg);
  user-select: none;
}

.faq-item summary:hover {
  background: #f1f5f9;
}

.faq-item p {
  padding: 0 18px 14px;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 20px 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.8rem;
  margin-top: auto;
}

/* 404 */
.error-page {
  text-align: center;
  padding: 80px 20px;
}

.error-page h1 {
  font-size: 4rem;
  color: var(--primary);
}

.error-page p {
  color: var(--text-secondary);
  margin-bottom: 24px;
}

/* Toast */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  background: #1e293b;
  color: #fff;
  padding: 10px 24px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  opacity: 0;
  transition: opacity 0.3s;
  z-index: 999;
  pointer-events: none;
}

.toast.show {
  opacity: 1;
}

/* Responsive */
@media (max-width: 640px) {
  h1 { font-size: 1.4rem; }
  .tool-grid { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .tool-card { padding: 14px; }
  .tool-card .tool-icon { font-size: 1.5rem; }
  .tool-card .tool-desc { display: none; }
  .tool-area { padding: 16px; }
  .diff-inputs { grid-template-columns: 1fr; }
  .tool-actions { flex-direction: column; }
  .tool-actions .btn { width: 100%; }
  .inline-actions .btn { flex: 1 1 auto; min-width: 0; font-size: 0.8rem; padding: 8px 10px; }
  .related-tools .tool-grid { grid-template-columns: repeat(2, 1fr); }
  .tool-options { flex-direction: column; align-items: stretch; }
  .tool-options label { flex-wrap: wrap; }
}