/* ==========================================
   CSS Variables & Warm Theme
   ========================================== */
@import url('https://fonts.googleapis.com/css2?family=Nunito:wght@400;500;600;700;800&family=JetBrains+Mono:wght@400;500;600&display=swap');

:root {
    /* Warm Theme Colors - Inspired by Mood Diary */
    --bg-primary: #f5efe6;
    --bg-secondary: #fff8f0;
    --bg-tertiary: #fefaf6;
    --bg-hover: #f0e6d8;
    --bg-card: #ffffff;
    
    /* Text Colors */
    --text-primary: #4a3f35;
    --text-secondary: #7a6b5e;
    --text-muted: #a89a8c;
    
    /* Accent Colors - Warm Orange/Yellow Palette */
    --accent-primary: #e07b39;
    --accent-secondary: #f4a261;
    --accent-success: #7cb342;
    --accent-warning: #ffb74d;
    --accent-error: #e57373;
    --accent-purple: #9575cd;
    --accent-teal: #4db6ac;
    --accent-cream: #fff3e0;
    
    /* Match Highlight Colors */
    --match-bg: rgba(224, 123, 57, 0.2);
    --match-border: #e07b39;
    --group-1: rgba(149, 117, 205, 0.25);
    --group-2: rgba(77, 182, 172, 0.25);
    --group-3: rgba(124, 179, 66, 0.25);
    --group-4: rgba(255, 183, 77, 0.25);
    
    /* Border & Shadow */
    --border-primary: #e8ddd0;
    --border-secondary: #f0e6d8;
    --shadow-sm: 0 2px 4px rgba(74, 63, 53, 0.08);
    --shadow-md: 0 4px 12px rgba(74, 63, 53, 0.12);
    --shadow-lg: 0 8px 24px rgba(74, 63, 53, 0.16);
    
    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 50px;
    
    /* Typography */
    --font-sans: 'Nunito', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', 'SF Mono', Consolas, monospace;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 350ms ease;
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    background: linear-gradient(135deg, #f5efe6 0%, #fff8f0 50%, #fef6eb 100%);
    background-attachment: fixed;
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

/* ==========================================
   App Container
   ========================================== */
.app-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-md);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ==========================================
   Header
   ========================================== */
.header {
    text-align: center;
    padding: var(--spacing-lg) 0;
    margin-bottom: var(--spacing-md);
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xs);
}

.logo-icon {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 700;
    color: #fff;
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
}

.header h1 {
    font-size: 1.75rem;
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.tagline {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    font-weight: 500;
}

/* ==========================================
   Main Content - Three Column Layout
   ========================================== */
.main-content {
    flex: 1;
    display: grid;
    grid-template-columns: 280px 1fr 320px;
    gap: var(--spacing-md);
    align-items: start;
}

.left-panel {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    position: sticky;
    top: var(--spacing-md);
    max-height: calc(100vh - 120px);
    overflow-y: auto;
}

.middle-panel {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.right-panel {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    position: sticky;
    top: var(--spacing-md);
    max-height: calc(100vh - 120px);
    overflow-y: auto;
}

/* ==========================================
   Sections - Card Style
   ========================================== */
.section {
    background: #ffffff;
    border: 2px solid var(--border-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
}

.section:hover {
    box-shadow: var(--shadow-md);
}

.section:focus-within {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(224, 123, 57, 0.12);
}

.section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-sm);
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.section-header h2 {
    font-size: 0.8125rem;
    font-weight: 700;
    color: var(--text-primary);
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

/* ==========================================
   Function Tabs
   ========================================== */
.function-tabs {
    display: flex;
    gap: var(--spacing-xs);
    flex-wrap: wrap;
}

.function-tab {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    font-family: var(--font-sans);
    font-size: 0.8125rem;
    font-weight: 600;
    background: var(--bg-primary);
    border: 2px solid var(--border-primary);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.function-tab:hover {
    background: var(--accent-cream);
    border-color: var(--accent-secondary);
}

.function-tab.active {
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    border-color: var(--accent-primary);
    color: #fff;
    box-shadow: var(--shadow-sm);
}

.tab-icon {
    font-size: 0.875rem;
}

/* ==========================================
   Regex Input Section
   ========================================== */
.flags-container {
    display: flex;
    gap: var(--spacing-xs);
}

.flag-label {
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    position: relative;
}

.flag-label input {
    position: absolute;
    opacity: 0;
    width: 0;
    height: 0;
}

.flag-label span {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    font-weight: 600;
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--bg-primary);
    border: 2px solid var(--border-primary);
    border-radius: var(--radius-sm);
    color: var(--text-muted);
    transition: all var(--transition-fast);
}

.flag-label input:checked + span {
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    border-color: var(--accent-primary);
    color: #fff;
    box-shadow: var(--shadow-sm);
}

.flag-label:hover span {
    border-color: var(--accent-secondary);
    background: var(--accent-cream);
}

.regex-input-wrapper {
    display: flex;
    align-items: center;
    background: var(--bg-tertiary);
    border: 2px solid var(--border-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-sm) var(--spacing-md);
    transition: all var(--transition-fast);
}

.regex-input-wrapper:focus-within {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 4px rgba(224, 123, 57, 0.12);
    background: #fff;
}

.regex-delimiter {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    color: var(--accent-primary);
    font-weight: 600;
}

.regex-input {
    flex: 1;
    font-family: var(--font-mono);
    font-size: 1.125rem;
    background: transparent;
    border: none;
    outline: none;
    color: var(--text-primary);
    padding: var(--spacing-sm);
}

.regex-input::placeholder {
    color: var(--text-muted);
}

.flags-display {
    font-family: var(--font-mono);
    font-size: 1rem;
    color: var(--accent-purple);
    font-weight: 600;
    padding-left: var(--spacing-xs);
}

.error-message {
    margin-top: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background: rgba(229, 115, 115, 0.15);
    border: 2px solid var(--accent-error);
    border-radius: var(--radius-md);
    color: var(--accent-error);
    font-family: var(--font-mono);
    font-size: 0.875rem;
    font-weight: 500;
    display: none;
}

.error-message.visible {
    display: block;
}

/* ==========================================
   Replace Input
   ========================================== */
.replace-input {
    width: 100%;
    font-family: var(--font-mono);
    font-size: 0.9375rem;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
    border: 2px solid var(--border-primary);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    outline: none;
    transition: all var(--transition-fast);
}

.replace-input:focus {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(224, 123, 57, 0.12);
    background: #fff;
}

/* ==========================================
   Action Bar
   ========================================== */
.action-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-md);
    flex-wrap: wrap;
    padding: var(--spacing-sm) 0;
}

.action-buttons {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.export-buttons {
    display: flex;
    gap: var(--spacing-xs);
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    font-family: var(--font-sans);
    font-size: 0.8125rem;
    font-weight: 700;
    border: 2px solid transparent;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-fast);
    text-transform: uppercase;
    letter-spacing: 0.02em;
}

.btn-icon {
    font-size: 0.75rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    color: #fff;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-primary:active {
    transform: translateY(0);
}

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

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

.btn-export {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    border-color: var(--border-primary);
    font-size: 0.6875rem;
    padding: var(--spacing-xs) var(--spacing-sm);
}

.btn-export:hover {
    background: var(--accent-cream);
    border-color: var(--accent-secondary);
    color: var(--accent-primary);
}

.btn-small {
    font-size: 0.6875rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--accent-cream);
    color: var(--accent-primary);
    border-color: var(--border-primary);
}

.btn-small:hover {
    background: var(--accent-primary);
    color: #fff;
}

/* ==========================================
   Test String Section - Fixed Overlay
   ========================================== */
.string-info {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-family: var(--font-mono);
    font-weight: 500;
    background: var(--accent-success);
    color: #fff;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
}

.textarea-container {
    position: relative;
    min-height: 180px;
}

.test-textarea {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    line-height: 1.6;
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    width: 100%;
    min-height: 180px;
    resize: vertical;
    white-space: pre-wrap;
    word-wrap: break-word;
    overflow-wrap: break-word;
    background: #fff;
    border: 2px solid var(--border-primary);
    color: var(--text-primary);
    outline: none;
    transition: all var(--transition-fast);
    position: relative;
    z-index: 2;
}

.test-textarea:focus {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(224, 123, 57, 0.12);
}

.test-textarea::placeholder {
    color: var(--text-muted);
}

.highlighted-layer {
    position: absolute;
    top: 2px;
    left: 2px;
    right: 2px;
    bottom: 2px;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    line-height: 1.6;
    padding: var(--spacing-md);
    border-radius: calc(var(--radius-md) - 2px);
    white-space: pre-wrap;
    word-wrap: break-word;
    overflow-wrap: break-word;
    overflow: hidden;
    pointer-events: none;
    z-index: 1;
    color: transparent;
    background: transparent;
}

.highlighted-layer .match {
    background: var(--match-bg);
    border-bottom: 2px solid var(--match-border);
    border-radius: 2px;
    color: transparent;
}

.highlighted-layer .group-1 { background: var(--group-1); }
.highlighted-layer .group-2 { background: var(--group-2); }
.highlighted-layer .group-3 { background: var(--group-3); }
.highlighted-layer .group-4 { background: var(--group-4); }

/* ==========================================
   Result Preview
   ========================================== */
.result-preview {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    line-height: 1.6;
    padding: var(--spacing-md);
    background: var(--bg-tertiary);
    border: 2px solid var(--border-secondary);
    border-radius: var(--radius-md);
    max-height: 200px;
    overflow-y: auto;
    white-space: pre-wrap;
    word-break: break-all;
}

/* ==========================================
   Stats Section
   ========================================== */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-sm);
}

.stat-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-sm);
    background: var(--bg-tertiary);
    border: 2px solid var(--border-secondary);
    border-radius: var(--radius-md);
}

.stat-card .stat-value {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--accent-primary);
}

.stat-card .stat-label {
    font-size: 0.6875rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
}

/* ==========================================
   Matches Section
   ========================================== */
.matches-container {
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    padding: var(--spacing-sm);
    max-height: 280px;
    overflow-y: auto;
    border: 2px solid var(--border-secondary);
}

.empty-state {
    text-align: center;
    padding: var(--spacing-lg);
    color: var(--text-muted);
}

.empty-icon {
    font-size: 2rem;
    margin-bottom: var(--spacing-xs);
}

.empty-state p {
    font-weight: 500;
    font-size: 0.8125rem;
}

.match-item {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm);
    background: #ffffff;
    border: 2px solid var(--border-primary);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-xs);
    transition: all var(--transition-fast);
}

.match-item:hover {
    border-color: var(--accent-secondary);
}

.match-item:last-child {
    margin-bottom: 0;
}

.match-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.match-number {
    font-family: var(--font-mono);
    font-size: 0.6875rem;
    font-weight: 700;
    color: #fff;
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    padding: 2px 8px;
    border-radius: var(--radius-full);
}

.match-position {
    font-family: var(--font-mono);
    font-size: 0.6875rem;
    font-weight: 500;
    color: var(--text-muted);
    background: var(--bg-primary);
    padding: 2px 6px;
    border-radius: var(--radius-sm);
}

.match-value {
    font-family: var(--font-mono);
    font-size: 0.8125rem;
    background: var(--match-bg);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    border-left: 3px solid var(--match-border);
    word-break: break-all;
    font-weight: 500;
}

.match-groups {
    display: flex;
    flex-direction: column;
    gap: 2px;
    padding-left: var(--spacing-sm);
    border-left: 2px solid var(--border-primary);
    margin-left: var(--spacing-xs);
}

.group-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-family: var(--font-mono);
    font-size: 0.75rem;
}

.group-label {
    color: var(--accent-purple);
    font-weight: 600;
    min-width: 50px;
}

.group-value {
    color: var(--text-primary);
    background: var(--bg-primary);
    padding: 2px 10px;
    border-radius: var(--radius-sm);
    font-weight: 500;
}

/* ==========================================
   Explanation Section
   ========================================== */
.explanation-container {
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    padding: var(--spacing-sm);
    max-height: 250px;
    overflow-y: auto;
    border: 2px solid var(--border-secondary);
}

.explanation-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.explanation-item {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-sm);
    padding: var(--spacing-xs) var(--spacing-sm);
    background: #ffffff;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-primary);
}

.explanation-token {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--accent-primary);
    background: var(--accent-cream);
    padding: 2px var(--spacing-xs);
    border-radius: var(--radius-sm);
    min-width: 50px;
    text-align: center;
    flex-shrink: 0;
}

.explanation-text {
    color: var(--text-secondary);
    font-size: 0.75rem;
    line-height: 1.4;
    font-weight: 500;
}

.token-anchor { color: var(--accent-warning); background: rgba(255, 183, 77, 0.2); }
.token-quantifier { color: var(--accent-success); background: rgba(124, 179, 66, 0.2); }
.token-group { color: var(--accent-purple); background: rgba(149, 117, 205, 0.2); }
.token-class { color: var(--accent-teal); background: rgba(77, 182, 172, 0.2); }
.token-escape { color: var(--accent-warning); background: rgba(255, 183, 77, 0.2); }

/* ==========================================
   Quick Reference Section
   ========================================== */
.toggle-btn {
    background: var(--bg-primary);
    border: 2px solid var(--border-primary);
    border-radius: var(--radius-sm);
    padding: var(--spacing-xs) var(--spacing-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.toggle-btn:hover {
    background: var(--accent-cream);
    border-color: var(--accent-secondary);
}

.toggle-icon {
    color: var(--text-secondary);
    font-size: 0.75rem;
    display: inline-block;
    transition: transform var(--transition-fast);
}

.toggle-icon.collapsed {
    transform: rotate(-90deg);
}

.reference-content {
    overflow-y: auto;
    transition: all var(--transition-normal);
    max-height: 350px;
}

.reference-content.collapsed {
    max-height: 0;
    padding: 0;
    overflow: hidden;
}

.explanation-content {
    overflow-y: auto;
    transition: all var(--transition-normal);
    max-height: 300px;
}

.explanation-content.collapsed {
    max-height: 0;
    padding: 0;
    overflow: hidden;
}

.reference-search {
    margin-bottom: var(--spacing-sm);
}

.reference-search-input {
    width: 100%;
    font-family: var(--font-sans);
    font-size: 0.8125rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--bg-tertiary);
    border: 2px solid var(--border-primary);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    outline: none;
}

.reference-search-input:focus {
    border-color: var(--accent-primary);
}

.reference-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.reference-category {
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    padding: var(--spacing-sm);
    border: 1px solid var(--border-secondary);
}

.reference-category h3 {
    font-size: 0.6875rem;
    font-weight: 700;
    color: var(--accent-primary);
    margin-bottom: var(--spacing-xs);
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.reference-category ul {
    list-style: none;
}

.reference-category li {
    font-size: 0.75rem;
    color: var(--text-secondary);
    padding: 2px 0;
    display: flex;
    gap: var(--spacing-xs);
    align-items: flex-start;
    font-weight: 500;
}

.reference-category code {
    font-family: var(--font-mono);
    font-size: 0.6875rem;
    background: var(--accent-cream);
    color: var(--accent-primary);
    padding: 1px 4px;
    border-radius: var(--radius-sm);
    white-space: nowrap;
    font-weight: 600;
}

/* ==========================================
   Footer
   ========================================== */
.footer {
    text-align: center;
    padding: var(--spacing-lg);
    margin-top: var(--spacing-lg);
    color: var(--text-muted);
    font-size: 0.875rem;
    font-weight: 500;
}

/* ==========================================
   Scrollbar Styling
   ========================================== */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: var(--border-primary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-secondary);
}

/* ==========================================
   Responsive Design
   ========================================== */
@media (max-width: 1200px) {
    .main-content {
        grid-template-columns: 250px 1fr 280px;
    }
}

@media (max-width: 1024px) {
    .main-content {
        grid-template-columns: 1fr 1fr;
        grid-template-rows: auto auto;
    }
    
    .left-panel {
        grid-column: 1 / 2;
        grid-row: 2 / 3;
        position: static;
        max-height: none;
    }
    
    .middle-panel {
        grid-column: 1 / 3;
        grid-row: 1 / 2;
    }
    
    .right-panel {
        grid-column: 2 / 3;
        grid-row: 2 / 3;
        position: static;
        max-height: none;
    }
}

@media (max-width: 768px) {
    .main-content {
        grid-template-columns: 1fr;
    }
    
    .left-panel,
    .middle-panel,
    .right-panel {
        grid-column: 1;
        grid-row: auto;
    }
    
    .app-container {
        padding: var(--spacing-sm);
    }
    
    .header {
        padding: var(--spacing-md) 0;
    }
    
    .header h1 {
        font-size: 1.5rem;
    }
    
    .logo-icon {
        font-size: 1.25rem;
        padding: var(--spacing-xs) var(--spacing-sm);
    }
    
    .section {
        padding: var(--spacing-sm);
    }
    
    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .flags-container {
        flex-wrap: wrap;
    }
    
    .regex-input-wrapper {
        flex-wrap: wrap;
    }
    
    .regex-input {
        font-size: 0.9375rem;
        min-width: 0;
    }
    
    .function-tabs {
        flex-wrap: wrap;
    }
    
    .function-tab {
        flex: 1;
        min-width: 80px;
        justify-content: center;
    }
    
    .action-bar {
        flex-direction: column;
    }
    
    .action-buttons,
    .export-buttons {
        width: 100%;
        justify-content: center;
    }
    
    .btn {
        flex: 1;
        justify-content: center;
    }
    
    .stats-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 1.25rem;
    }
    
    .tagline {
        font-size: 0.8125rem;
    }
    
    .regex-delimiter {
        font-size: 1.25rem;
    }
    
    .flags-display {
        font-size: 0.75rem;
    }
    
    .logo {
        flex-direction: column;
        gap: var(--spacing-xs);
    }
    
    .function-tab {
        font-size: 0.6875rem;
        padding: var(--spacing-xs) var(--spacing-sm);
    }
    
    .tab-icon {
        display: none;
    }
}

/* ==========================================
   Animations
   ========================================== */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.02);
    }
}

.match-item {
    animation: fadeIn var(--transition-normal);
}

.btn-primary:active {
    animation: pulse 0.2s ease;
}

/* ==========================================
   Test Result Styling
   ========================================== */
.test-result {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    font-size: 1.25rem;
    font-weight: 600;
    text-align: center;
}

.test-result.success {
    background: linear-gradient(135deg, rgba(46, 160, 67, 0.15), rgba(46, 160, 67, 0.05));
    border: 2px solid rgba(46, 160, 67, 0.3);
    color: #2ea043;
}

.test-result.failure {
    background: linear-gradient(135deg, rgba(248, 81, 73, 0.15), rgba(248, 81, 73, 0.05));
    border: 2px solid rgba(248, 81, 73, 0.3);
    color: #f85149;
}

.test-result .result-icon {
    font-size: 2rem;
}

/* ==========================================
   Result Preview Styling
   ========================================== */
.result-preview {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    font-family: var(--font-mono);
    font-size: 0.875rem;
    line-height: 1.6;
    white-space: pre-wrap;
    word-break: break-word;
    color: var(--text-primary);
    max-height: 200px;
    overflow-y: auto;
}

.split-items {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.split-item {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    font-family: var(--font-mono);
    font-size: 0.8125rem;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.split-index {
    background: var(--accent-primary);
    color: white;
    font-size: 0.6875rem;
    font-weight: 600;
    padding: 2px 6px;
    border-radius: var(--radius-sm);
    font-family: var(--font-sans);
}

/* ==========================================
   Selection Styling
   ========================================== */
::selection {
    background: rgba(224, 123, 57, 0.3);
    color: var(--text-primary);
}

/* ==========================================
   Focus Visible
   ========================================== */
:focus-visible {
    outline: 3px solid var(--accent-primary);
    outline-offset: 2px;
}

input:focus-visible,
textarea:focus-visible,
button:focus-visible {
    outline: none;
}