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

:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #edf5ff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --accent-primary: #0f4ba5;
    --accent-hover: #0098ff;
    --added: #4a7c59;
    --added-bg: rgba(74, 124, 89, 0.3);
    --removed: #c75450;
    --removed-bg: rgba(199, 84, 80, 0.3);
    --unchanged: transparent;
    --border-color: #e2e8f0;
    --success: #4ec9b0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--accent-primary), var(--success));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.toolbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--bg-secondary);
    padding: 1rem 1.5rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.comparison-modes {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.comparison-modes label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.mode-btn {
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.5rem 1rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s ease;
}

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

.mode-btn.active {
    background-color: var(--accent-primary);
    border-color: var(--accent-primary);
    color: white;
}

.actions {
    display: flex;
    gap: 0.75rem;
}

.btn-primary, .btn-secondary {
    padding: 0.6rem 1.5rem;
    border: none;
    border-radius: 6px;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all 0.2s ease;
    font-weight: 500;
}

.btn-primary {
    background-color: var(--accent-primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--accent-hover);
    transform: translateY(-1px);
}

.btn-secondary {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

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

.input-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

@media (max-width: 968px) {
    .input-section {
        grid-template-columns: 1fr;
    }
    
    .toolbar {
        flex-direction: column;
        align-items: stretch;
    }
    
    .comparison-modes {
        justify-content: center;
    }
}

.input-group {
    background-color: var(--bg-secondary);
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid var(--border-color);
}

.input-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.25rem;
    background-color: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
}

.input-header label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.95rem;
}

.file-upload {
    position: relative;
}

.file-upload input[type="file"] {
    position: absolute;
    opacity: 0;
    width: 0;
    height: 0;
}

.file-label {
    display: inline-block;
    padding: 0.4rem 0.75rem;
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.85rem;
    color: var(--text-secondary);
    transition: all 0.2s ease;
}

.file-label:hover {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    border-color: var(--accent-primary);
}

textarea {
    width: 100%;
    min-height: 250px;
    padding: 1rem;
    border: none;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
    font-size: 0.9rem;
    resize: vertical;
    outline: none;
    line-height: 1.7;
}

textarea::placeholder {
    color: var(--text-secondary);
}

textarea:focus {
    background-color: var(--bg-primary);
}

.input-stats {
    padding: 0.75rem 1.25rem;
    background-color: var(--bg-tertiary);
    border-top: 1px solid var(--border-color);
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.results-section {
    background-color: var(--bg-secondary);
    border-radius: 8px;
    padding: 1.5rem;
    border: 1px solid var(--border-color);
    animation: fadeIn 0.3s ease;
}

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

.results-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.results-header h2 {
    font-size: 1.4rem;
    font-weight: 600;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1rem;
    margin-bottom: 1.5rem;
}

@media (max-width: 768px) {
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.stat-card {
    background-color: var(--bg-tertiary);
    padding: 1.25rem;
    border-radius: 8px;
    text-align: center;
    border: 1px solid var(--border-color);
    transition: transform 0.2s ease;
}

.stat-card:hover {
    transform: translateY(-2px);
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-primary);
    margin-bottom: 0.25rem;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.legend {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
    padding: 1rem;
    background-color: var(--bg-tertiary);
    border-radius: 6px;
    justify-content: center;
    flex-wrap: wrap;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.legend-color {
    width: 20px;
    height: 20px;
    border-radius: 4px;
}

.legend-color.added {
    background-color: var(--added);
}

.legend-color.removed {
    background-color: var(--removed);
}

.legend-color.unchanged {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
}

.comparison-output {
    background-color: var(--bg-primary);
    border-radius: 8px;
    padding: 1.5rem;
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.8;
    max-height: 500px;
    overflow-y: auto;
    border: 1px solid var(--border-color);
}

.comparison-output::-webkit-scrollbar {
    width: 10px;
}

.comparison-output::-webkit-scrollbar-track {
    background: var(--bg-secondary);
    border-radius: 4px;
}

.comparison-output::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

.comparison-output::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}

.diff-word {
    display: inline;
    padding: 0.1rem 0.25rem;
    border-radius: 3px;
    margin: 0 1px;
}

.diff-word.added {
    background-color: var(--added-bg);
    color: #7ee787;
    text-decoration: none;
}

.diff-word.removed {
    background-color: var(--removed-bg);
    color: #ffa198;
    text-decoration: line-through;
}

.diff-word.unchanged {
    background-color: var(--unchanged);
    color: var(--text-primary);
}

.diff-char {
    display: inline;
    padding: 0;
    margin: 0;
}

.diff-char.added {
    background-color: var(--added);
    color: white;
}

.diff-char.removed {
    background-color: var(--removed);
    color: white;
    text-decoration: line-through;
}

.diff-line {
    margin: 0.25rem 0;
    padding: 0.25rem 0;
}

.notification {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 1rem 1.5rem;
    background-color: var(--success);
    color: var(--bg-primary);
    border-radius: 6px;
    font-weight: 500;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    animation: slideIn 0.3s ease;
    z-index: 1000;
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.empty-state {
    text-align: center;
    padding: 3rem;
    color: var(--text-secondary);
}

.empty-state svg {
    width: 64px;
    height: 64px;
    margin-bottom: 1rem;
    opacity: 0.5;
}