/* === Reset & Base === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0f172a;
  --bg-card: #1e293b;
  --bg-input: #0f172a;
  --border: #334155;
  --border-focus: #3b82f6;
  --text: #e2e8f0;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --secondary: #475569;
  --secondary-hover: #64748b;
  --success: #22c55e;
  --error: #ef4444;
  --warning: #f59e0b;
  --diff-add: rgba(34,197,94,0.15);
  --diff-remove: rgba(239,68,68,0.15);
  --radius: 8px;
  --radius-sm: 6px;
  --font-mono: 'SF Mono', 'Fira Code', 'Cascadia Code', 'JetBrains Mono', monospace;
  --font-ui: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

html { font-size: 15px; }
body {
  font-family: var(--font-ui);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}

.container { max-width: 1100px; margin: 0 auto; padding: 0 20px; }

/* === Header === */
.header {
  border-bottom: 1px solid var(--border);
  padding: 20px 0;
  background: linear-gradient(135deg, #0f172a 0%, #1a2a4a 100%);
}
.header-inner { display: flex; align-items: baseline; gap: 16px; flex-wrap: wrap; }
.logo { font-size: 1.5rem; font-weight: 700; color: var(--text); letter-spacing: -0.5px; }
.tagline { color: var(--text-muted); font-size: 0.9rem; }

/* === Tabs === */
.tabs {
  display: flex; gap: 2px; margin-top: 24px;
  background: var(--bg-card); border-radius: var(--radius) var(--radius) 0 0; padding: 4px;
  overflow-x: auto;
}
.tab {
  display: flex; align-items: center; gap: 6px;
  padding: 10px 18px; border: none; background: transparent; color: var(--text-muted);
  font-size: 0.9rem; font-family: var(--font-ui); cursor: pointer; border-radius: var(--radius-sm);
  white-space: nowrap; transition: all 0.15s;
}
.tab:hover { color: var(--text); background: rgba(255,255,255,0.05); }
.tab.active {
  color: #fff; background: var(--primary);
  box-shadow: 0 2px 8px rgba(59,130,246,0.3);
}
.tab:focus-visible { outline: 2px solid var(--primary); outline-offset: -2px; }
.tab-icon { font-size: 1.1rem; }

/* === Tab Panels === */
.tab-panel { display: none; }
.tab-panel.active { display: block; }

.panel-header { padding: 20px 0 12px; }
.panel-header h2 { font-size: 1.15rem; font-weight: 600; margin-bottom: 4px; }
.panel-header p { color: var(--text-muted); font-size: 0.85rem; }

/* === Tool Layout === */
.tool-layout {
  display: flex; flex-direction: column; gap: 12px;
  background: var(--bg-card); padding: 16px; border-radius: var(--radius);
  border: 1px solid var(--border);
}
.compare-layout {
  flex-direction: row;
}
@media (max-width: 700px) {
  .compare-layout { flex-direction: column; }
}

/* === Editor === */
.editor-section { flex: 1; min-width: 0; }
.editor-header {
  display: flex; justify-content: space-between; align-items: center;
  margin-bottom: 6px;
}
.editor-header label { font-size: 0.82rem; font-weight: 600; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.5px; }
.editor-actions { display: flex; gap: 6px; align-items: center; }

.code-editor {
  width: 100%; min-height: 280px; padding: 14px;
  background: var(--bg-input); color: var(--text);
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  font-family: var(--font-mono); font-size: 0.85rem; line-height: 1.5;
  resize: vertical; tab-size: 4;
  transition: border-color 0.15s;
}
.code-editor:focus { outline: none; border-color: var(--border-focus); box-shadow: 0 0 0 2px rgba(59,130,246,0.15); }
.code-editor[readonly] { cursor: default; }
.code-editor[readonly]:focus { border-color: var(--border); box-shadow: none; }
.code-editor::placeholder { color: var(--text-dim); }
.code-editor-half { min-height: 220px; }

/* === Controls === */
.controls {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap; padding: 4px 0;
}
.control-group {
  display: flex; align-items: center; gap: 8px;
}
.control-group label { font-size: 0.82rem; color: var(--text-muted); }

select {
  padding: 6px 10px; background: var(--bg-input); color: var(--text);
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  font-size: 0.85rem; cursor: pointer;
}
select:focus { outline: none; border-color: var(--border-focus); }

/* === Buttons === */
.btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 8px 16px; border: none; border-radius: var(--radius-sm);
  font-size: 0.85rem; font-family: var(--font-ui); font-weight: 500;
  cursor: pointer; transition: all 0.15s; white-space: nowrap;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-hover); box-shadow: 0 2px 8px rgba(59,130,246,0.3); }
.btn-secondary { background: var(--secondary); color: #fff; }
.btn-secondary:hover { background: var(--secondary-hover); }
.btn-sm { padding: 4px 10px; font-size: 0.78rem; background: var(--secondary); color: #e2e8f0; }
.btn-sm:hover { background: var(--secondary-hover); }

.checkbox-label {
  display: flex; align-items: center; gap: 6px;
  font-size: 0.82rem; color: var(--text-muted); cursor: pointer;
}

/* === Status Bar === */
.status-bar {
  margin-top: 8px; padding: 10px 14px; border-radius: var(--radius-sm);
  font-size: 0.85rem; min-height: 0; transition: all 0.2s;
  display: none;
}
.status-bar.visible { display: block; }
.status-success { background: rgba(34,197,94,0.1); color: var(--success); border: 1px solid rgba(34,197,94,0.2); }
.status-error { background: rgba(239,68,68,0.1); color: var(--error); border: 1px solid rgba(239,68,68,0.2); }
.status-info { background: rgba(59,130,246,0.1); color: var(--primary); border: 1px solid rgba(59,130,246,0.2); }

/* === Compare Result === */
.compare-result {
  margin-top: 12px;
  background: var(--bg-card); padding: 16px; border-radius: var(--radius);
  border: 1px solid var(--border);
  font-family: var(--font-mono); font-size: 0.82rem; line-height: 1.5;
  white-space: pre-wrap; overflow-x: auto; display: none;
}
.compare-result.visible { display: block; }
.diff-added { background: var(--diff-add); display: inline; }
.diff-removed { background: var(--diff-remove); display: inline; }

/* === Size Badge === */
.size-badge {
  font-size: 0.75rem; color: var(--text-dim);
  background: var(--bg-input); padding: 2px 8px; border-radius: 10px;
  border: 1px solid var(--border);
}

/* === Footer === */
.footer {
  text-align: center; padding: 32px 0; margin-top: 40px;
  border-top: 1px solid var(--border); color: var(--text-dim); font-size: 0.82rem;
}
.footer-small { margin-top: 4px; font-size: 0.75rem; }

/* === Toast Notification === */
.toast {
  position: fixed; bottom: 24px; left: 50%; transform: translateX(-50%);
  padding: 10px 24px; border-radius: var(--radius); background: var(--bg-card);
  border: 1px solid var(--border); color: var(--text); font-size: 0.85rem;
  box-shadow: 0 4px 20px rgba(0,0,0,0.3); z-index: 100;
  animation: toastIn 0.3s ease;
}
@keyframes toastIn {
  from { opacity: 0; transform: translateX(-50%) translateY(10px); }
  to { opacity: 1; transform: translateX(-50%) translateY(0); }
}
/* === SEO / GEO Content === */
.language-switcher { margin-left: auto; display: inline-flex; gap: 4px; padding: 3px; border: 1px solid var(--border); border-radius: var(--radius-xs); background: rgba(15,23,42,0.35); }
.language-switcher a { color: var(--text-muted); text-decoration: none; font-size: 0.76rem; line-height: 1; padding: 6px 8px; border-radius: 5px; }
.language-switcher a:hover, .language-switcher a.active { color: #fff; background: var(--primary); }
.seo-content { margin-top: 28px; display: flex; flex-direction: column; gap: 16px; color: var(--text-muted); }
.seo-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
.seo-block { background: rgba(255,255,255,0.03); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 18px; }
.seo-block h2 { color: var(--text); font-size: 1rem; line-height: 1.35; margin: 0 0 10px; letter-spacing: 0; }
.seo-block p { margin: 0; }
.seo-block ul { margin: 0; padding-left: 18px; }
.seo-block li + li { margin-top: 6px; }
.faq-list details { border-top: 1px solid var(--border); padding: 10px 0; }
.faq-list details:first-of-type { border-top: 0; }
.faq-list summary { color: var(--text); cursor: pointer; font-weight: 600; }
.faq-list details p { margin-top: 8px; }
@media (max-width: 720px) { .language-switcher { margin-left: 0; } .seo-grid { grid-template-columns: 1fr; } }
.related-links { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 10px; }
.related-links a { color: var(--text); text-decoration: none; border: 1px solid var(--border); border-radius: var(--radius-xs); padding: 7px 10px; background: rgba(255,255,255,0.04); }
.related-links a:hover { border-color: var(--primary); color: #fff; }