/* CSS Variables for theming */
:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --secondary-color: #6b7280;
    --secondary-hover: #4b5563;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;

    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --bg-card: #1e293b;

    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;

    --border-color: #334155;
    --border-radius: 8px;
    --border-radius-lg: 12px;

    --added-bg: rgba(16, 185, 129, 0.2);
    --added-border: #10b981;
    --removed-bg: rgba(239, 68, 68, 0.2);
    --removed-border: #ef4444;
    --modified-bg: rgba(245, 158, 11, 0.2);
    --modified-border: #f59e0b;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);

    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
}

/* Reset and base styles */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

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

/* App container */
.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Header styles */
.header {
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-tertiary) 100%);
    border-bottom: 1px solid var(--border-color);
    padding: 1.5rem;
}

.header-content {
    max-width: 1600px;
    margin: 0 auto;
    text-align: center;
}

.logo-section {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
}

.logo {
    width: 40px;
    height: 40px;
    object-fit: contain;
}

.header h1 {
    font-size: 1.75rem;
    font-weight: 700;
    background: linear-gradient(135deg, #818cf8 0%, #c084fc 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.tagline {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Main content */
.main-content {
    flex: 1;
    max-width: 1600px;
    margin: 0 auto;
    padding: 1.5rem;
    width: 100%;
}

/* Controls bar */
.controls-bar {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    background: var(--bg-card);
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--border-color);
    margin-bottom: 1.5rem;
}

.control-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.control-group label {
    color: var(--text-secondary);
    font-size: 0.875rem;
    white-space: nowrap;
}

.checkbox-group {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
}

.checkbox-group label {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    cursor: pointer;
}

.checkbox-group input[type="checkbox"] {
    width: 16px;
    height: 16px;
    accent-color: var(--primary-color);
    cursor: pointer;
}

select {
    padding: 0.5rem 2rem 0.5rem 0.75rem;
    font-size: 0.875rem;
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' fill='%2394a3b8' viewBox='0 0 16 16'%3E%3Cpath d='M8 11L3 6h10l-5 5z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.5rem center;
}

select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(79, 70, 229, 0.3);
}

.button-group {
    display: flex;
    gap: 0.5rem;
    margin-left: auto;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
    font-weight: 500;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

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

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

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

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

.btn-small {
    padding: 0.375rem 0.75rem;
    font-size: 0.8rem;
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-small:hover {
    background: var(--secondary-hover);
}

.btn-icon {
    font-size: 1rem;
}

.btn-icon-only {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: 1rem;
}

.btn-icon-only:hover {
    background: var(--bg-tertiary);
    border-color: var(--text-muted);
}

/* Editor section */
.editor-section {
    margin-bottom: 1.5rem;
}

.input-panels {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.input-panel {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem 1rem;
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
}

.panel-header h3 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
}

.panel-actions {
    display: flex;
    gap: 0.5rem;
}

.hidden-file-input {
    display: none;
}

textarea {
    width: 100%;
    min-height: 250px;
    padding: 1rem;
    font-family: 'Fira Code', 'Monaco', 'Consolas', monospace;
    font-size: 0.875rem;
    line-height: 1.5;
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: none;
    resize: vertical;
}

textarea:focus {
    outline: none;
    background: rgba(30, 41, 59, 0.8);
}

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

/* Diff section */
.diff-section {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    display: none;
}

.diff-section.visible {
    display: block;
}

.diff-header {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
}

.diff-header h2 {
    font-size: 1rem;
    font-weight: 600;
}

.diff-stats {
    display: flex;
    gap: 1rem;
    font-size: 0.85rem;
}

.diff-stats .stat {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.diff-stats .added {
    color: var(--success-color);
}

.diff-stats .removed {
    color: var(--danger-color);
}

.diff-stats .modified {
    color: var(--warning-color);
}

.diff-actions {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-left: auto;
}

.change-counter {
    font-size: 0.85rem;
    color: var(--text-secondary);
    padding: 0 0.5rem;
}

.diff-legend {
    display: flex;
    gap: 1.5rem;
    padding: 0.75rem 1rem;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    font-size: 0.8rem;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    color: var(--text-secondary);
}

.legend-color {
    width: 12px;
    height: 12px;
    border-radius: 2px;
}

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

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

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

.diff-output {
    padding: 1rem;
    overflow-x: auto;
}

/* Diff view styles */
.diff-container {
    font-family: 'Fira Code', 'Monaco', 'Consolas', monospace;
    font-size: 0.85rem;
    line-height: 1.6;
}

/* Split view */
.diff-split {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.diff-pane {
    background: var(--bg-secondary);
    border-radius: var(--border-radius);
    overflow: hidden;
}

.diff-pane-header {
    padding: 0.5rem 1rem;
    background: var(--bg-tertiary);
    font-weight: 600;
    font-size: 0.8rem;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border-color);
}

.diff-pane-content {
    padding: 0.5rem 0;
    max-height: 500px;
    overflow-y: auto;
}

/* Unified and inline views */
.diff-unified,
.diff-inline {
    background: var(--bg-secondary);
    border-radius: var(--border-radius);
    padding: 0.5rem 0;
    max-height: 600px;
    overflow-y: auto;
}

/* Diff lines */
.diff-line {
    display: flex;
    padding: 0 1rem;
    min-height: 1.6em;
    transition: background var(--transition-fast);
}

.diff-line:hover {
    background: rgba(255, 255, 255, 0.03);
}

.diff-line.highlight {
    background: rgba(79, 70, 229, 0.2) !important;
}

.line-number {
    flex-shrink: 0;
    width: 40px;
    padding-right: 0.75rem;
    text-align: right;
    color: var(--text-muted);
    user-select: none;
    font-size: 0.8rem;
}

.line-number.hidden {
    visibility: hidden;
}

.line-prefix {
    flex-shrink: 0;
    width: 20px;
    text-align: center;
    font-weight: 600;
    user-select: none;
}

.line-content {
    flex: 1;
    white-space: pre-wrap;
    word-break: break-all;
    padding-left: 0.5rem;
}

/* Line types */
.diff-line.added {
    background: var(--added-bg);
}

.diff-line.added .line-prefix {
    color: var(--success-color);
}

.diff-line.removed {
    background: var(--removed-bg);
}

.diff-line.removed .line-prefix {
    color: var(--danger-color);
}

.diff-line.modified {
    background: var(--modified-bg);
}

.diff-line.modified .line-prefix {
    color: var(--warning-color);
}

/* Character-level highlighting */
.char-added {
    background: rgba(16, 185, 129, 0.4);
    border-radius: 2px;
}

.char-removed {
    background: rgba(239, 68, 68, 0.4);
    border-radius: 2px;
}

/* Empty state */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-muted);
}

.empty-state-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.empty-state h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

/* No difference state */
.no-diff {
    text-align: center;
    padding: 2rem;
    color: var(--success-color);
}

.no-diff-icon {
    font-size: 2.5rem;
    margin-bottom: 0.75rem;
}

/* Footer */
.footer {
    text-align: center;
    padding: 1.5rem;
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    margin-top: auto;
}

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

.footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition-fast);
}

.footer a:hover {
    color: #818cf8;
    text-decoration: underline;
}

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

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

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

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

/* Toast notifications */
.toast {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    padding: 0.75rem 1.25rem;
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
    z-index: 1000;
    animation: slideIn 0.3s ease, fadeOut 0.3s ease 2.7s;
}

.toast.success {
    border-color: var(--success-color);
}

.toast.error {
    border-color: var(--danger-color);
}

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

@keyframes fadeOut {
    to {
        opacity: 0;
    }
}

/* Responsive design */
@media (max-width: 1024px) {
    .controls-bar {
        flex-direction: column;
        align-items: stretch;
    }

    .button-group {
        margin-left: 0;
        justify-content: center;
    }

    .checkbox-group {
        justify-content: center;
    }

    .control-group {
        justify-content: center;
    }

    .diff-split {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .header {
        padding: 1rem;
    }

    .header h1 {
        font-size: 1.4rem;
    }

    .main-content {
        padding: 1rem;
    }

    .input-panels {
        grid-template-columns: 1fr;
    }

    textarea {
        min-height: 180px;
    }

    .diff-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .diff-actions {
        margin-left: 0;
        flex-wrap: wrap;
    }

    .diff-legend {
        flex-wrap: wrap;
        gap: 0.75rem;
    }

    .btn {
        padding: 0.5rem 0.75rem;
        font-size: 0.8rem;
    }

    .line-number {
        width: 30px;
        font-size: 0.7rem;
    }
}

@media (max-width: 480px) {
    .logo-section {
        flex-direction: column;
        gap: 0.5rem;
    }

    .header h1 {
        font-size: 1.2rem;
    }

    .tagline {
        font-size: 0.85rem;
    }

    .panel-header {
        flex-direction: column;
        gap: 0.5rem;
        align-items: flex-start;
    }

    .button-group {
        flex-wrap: wrap;
    }

    .diff-stats {
        flex-wrap: wrap;
        gap: 0.5rem;
    }
}