:root {
  --bg-primary: #0f1117;
  --bg-secondary: #161822;
  --bg-tertiary: #1c1f2e;
  --bg-elevated: #232638;
  --bg-input: #0c0d12;
  --border: #2a2d3e;
  --border-focus: #5b6abf;
  --text-primary: #e2e4ed;
  --text-secondary: #8b8fa4;
  --text-muted: #5c6078;
  --accent: #6c7bd4;
  --accent-hover: #7d8be0;
  --accent-subtle: rgba(108, 123, 212, 0.12);
  --accent-glow: rgba(108, 123, 212, 0.25);
  --success: #5bad78;
  --warning: #d4a55c;
  --danger: #c95f5f;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
  --font-sans: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.5);
}

@media (prefers-color-scheme: light) {
  :root {
    --bg-primary: #f5f6fa;
    --bg-secondary: #ffffff;
    --bg-tertiary: #ecedf3;
    --bg-elevated: #ffffff;
    --bg-input: #ffffff;
    --border: #d8dae5;
    --border-focus: #6c7bd4;
    --text-primary: #1a1c2e;
    --text-secondary: #5c6078;
    --text-muted: #8b8fa4;
    --accent: #5b6abf;
    --accent-hover: #4a59b0;
    --accent-subtle: rgba(91, 106, 191, 0.08);
    --accent-glow: rgba(91, 106, 191, 0.15);
    --success: #3d8a5a;
    --warning: #b8863a;
    --danger: #b84545;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
    --shadow-lg: 0 8px 30px rgba(0,0,0,0.12);
  }
}

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

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  min-height: 100vh;
}

.app-container {
  max-width: 960px;
  margin: 0 auto;
  padding: 24px 20px 40px;
}

/* Header */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border);
}
.header-left { display: flex; align-items: baseline; gap: 10px; }
.header h1 {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 600;
  letter-spacing: -0.5px;
  color: var(--text-primary);
}
.header .badge {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-subtle);
  padding: 2px 8px;
  border-radius: 20px;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}
.header-actions { display: flex; gap: 6px; align-items: center; }

/* Buttons */
.btn {
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 500;
  padding: 7px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-elevated);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
  white-space: nowrap;
  user-select: none;
}
.btn:hover { background: var(--bg-tertiary); color: var(--text-primary); border-color: var(--border-focus); }
.btn:active { transform: scale(0.97); }
.btn:disabled { opacity: 0.35; cursor: not-allowed; }
.btn:disabled:hover { background: var(--bg-elevated); color: var(--text-secondary); border-color: var(--border); }
.btn-accent {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.btn-accent:hover { background: var(--accent-hover); border-color: var(--accent-hover); color: #fff; }
.btn-sm { font-size: 12px; padding: 5px 10px; }
.btn-icon {
  padding: 7px 9px;
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 34px;
}
.btn-icon svg { width: 16px; height: 16px; }

/* Textarea */
.textarea-wrapper {
  position: relative;
  margin-bottom: 8px;
}
.main-textarea {
  width: 100%;
  min-height: 280px;
  max-height: 60vh;
  padding: 16px 18px;
  font-family: var(--font-mono);
  font-size: 13.5px;
  line-height: 1.65;
  color: var(--text-primary);
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  resize: vertical;
  outline: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
  tab-size: 4;
}
.main-textarea:focus {
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--accent-glow);
}
.main-textarea::placeholder { color: var(--text-muted); }

/* Stats bar */
.stats-bar {
  display: flex;
  gap: 20px;
  padding: 6px 4px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  color: var(--text-muted);
  margin-bottom: 20px;
}
.stats-bar span strong {
  color: var(--text-secondary);
  font-weight: 500;
}

/* Status message */
.status-msg {
  font-family: var(--font-mono);
  font-size: 12px;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  margin-bottom: 16px;
  animation: fadeIn 0.2s ease;
  border: 1px solid;
}
.status-msg.success { color: var(--success); background: rgba(93,173,120,0.08); border-color: rgba(93,173,120,0.2); }
.status-msg.error { color: var(--danger); background: rgba(201,95,95,0.08); border-color: rgba(201,95,95,0.2); }

@keyframes fadeIn { from { opacity: 0; transform: translateY(-4px); } to { opacity: 1; transform: translateY(0); } }

/* Category tabs */
.category-tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 12px;
  flex-wrap: wrap;
  padding: 4px;
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
}
.cat-tab {
  font-family: var(--font-sans);
  font-size: 12.5px;
  font-weight: 500;
  padding: 7px 14px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}
.cat-tab:hover { color: var(--text-primary); background: var(--bg-tertiary); }
.cat-tab.active {
  color: var(--text-primary);
  background: var(--bg-elevated);
  box-shadow: var(--shadow-sm);
}

/* Operation buttons grid */
.ops-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 20px;
}
.op-btn {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 400;
  padding: 8px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-secondary);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}
.op-btn:hover {
  background: var(--accent-subtle);
  border-color: var(--accent);
  color: var(--text-primary);
}
.op-btn:active { transform: scale(0.97); }

/* Regex panel */
.regex-panel {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px;
  margin-bottom: 20px;
}
.regex-panel h3 {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.8px;
  margin-bottom: 14px;
}
.regex-row {
  display: flex;
  gap: 10px;
  margin-bottom: 10px;
  align-items: center;
}
.regex-row label {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-muted);
  min-width: 65px;
  flex-shrink: 0;
}
.regex-input {
  flex: 1;
  font-family: var(--font-mono);
  font-size: 13px;
  padding: 8px 12px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  outline: none;
  transition: border-color 0.15s ease;
}
.regex-input:focus { border-color: var(--border-focus); }
.regex-input::placeholder { color: var(--text-muted); }

.regex-flags { display: flex; gap: 12px; align-items: center; }
.regex-flags label {
  display: flex;
  align-items: center;
  gap: 5px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-secondary);
  cursor: pointer;
  min-width: auto;
}
.regex-flags input[type="checkbox"] {
  accent-color: var(--accent);
  width: 14px;
  height: 14px;
}

.regex-actions {
  display: flex;
  gap: 8px;
  align-items: center;
  margin-top: 12px;
}
.match-count {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-muted);
  margin-left: auto;
}

.regex-error {
  font-family: var(--font-mono);
  font-size: 11.5px;
  color: var(--danger);
  margin-top: 6px;
}

/* Common patterns dropdown */
.patterns-row {
  display: flex;
  gap: 8px;
  align-items: center;
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
}
.patterns-row label { min-width: 65px; }
.pattern-select {
  font-family: var(--font-mono);
  font-size: 12px;
  padding: 6px 10px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  outline: none;
  cursor: pointer;
}
.pattern-select:focus { border-color: var(--border-focus); }

/* Keyboard shortcuts help */
.shortcuts-panel {
  font-family: var(--font-mono);
  font-size: 11.5px;
  color: var(--text-muted);
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  padding: 10px 4px;
}
.shortcuts-panel kbd {
  font-family: var(--font-mono);
  font-size: 10.5px;
  padding: 2px 6px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--text-secondary);
}

/* Privacy note */
.privacy-note {
  font-family: var(--font-mono);
  font-size: 10.5px;
  color: var(--text-muted);
  text-align: center;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  margin-top: 16px;
}
.privacy-note .lock { opacity: 0.6; }

/* Copy button */
.copy-float {
  position: absolute;
  top: 10px;
  right: 10px;
  z-index: 2;
}

/* Tab width config */
.config-row {
  display: flex;
  gap: 8px;
  align-items: center;
  margin-bottom: 10px;
}
.config-row label {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-muted);
}
.config-input {
  font-family: var(--font-mono);
  font-size: 12px;
  width: 50px;
  padding: 4px 8px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  outline: none;
  text-align: center;
}
.config-input:focus { border-color: var(--border-focus); }

/* Responsive */
@media (max-width: 640px) {
  .app-container { padding: 16px 12px 32px; }
  .header h1 { font-size: 18px; }
  .main-textarea { min-height: 200px; font-size: 13px; }
  .stats-bar { gap: 12px; font-size: 11px; }
  .cat-tab { font-size: 11.5px; padding: 6px 10px; }
  .op-btn { font-size: 11px; padding: 6px 10px; }
}