:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --secondary-color: #10b981;
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --card-border: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --input-bg: #0f172a;
    --success-color: #22c55e;
    --error-color: #ef4444;
    --warning-color: #f59e0b;
    --diff-added-bg: #dcfce7;
    --diff-removed-bg: #fee2e2;
    --diff-added-text: #166534;
    --diff-removed-text: #991b1b;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #fff;
    color: #181818;
    min-height: 100vh;
    line-height: 1.6;
    transition: background 0.3s, color 0.3s;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 20px;
    padding: 20px;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

/* Compare Section - Two Panel Layout */
.compare-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 20px;
}

@media (max-width: 900px) {
    .compare-section {
        grid-template-columns: 1fr;
    }
}

.input-panel {
    background: #fff;
    border: 1px solid #e5e7eb;
    border-radius: 12px;
    padding: 20px;
    transition: background 0.3s, border-color 0.3s;
}

.dark-mode .input-panel {
    background: #23272b !important;
    border-color: #2d3237 !important;
}

.panel-header {
    margin-bottom: 15px;
}

.panel-header h2 {
    font-size: 1.1rem;
    margin-bottom: 10px;
    color: #181818;
    font-weight: 700;
}

.dark-mode .panel-header h2 {
    color: #e5e7eb !important;
}

/* Input Type Selector */
.input-type-selector {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.input-type-selector label {
    display: flex;
    align-items: center;
    gap: 6px;
    cursor: pointer;
    padding: 8px 14px;
    background: #f3f4f6;
    border: 2px solid #e5e7eb;
    border-radius: 6px;
    color: #181818;
    font-weight: 500;
    font-size: 0.85rem;
    transition: all 0.3s;
}

.input-type-selector label:hover {
    border-color: #6366f1;
    background: #e0e7ff;
}

.input-type-selector input {
    accent-color: #6366f1;
}

.input-type-selector input:checked + span {
    color: #6366f1;
    font-weight: 700;
}

.dark-mode .input-type-selector label {
    background: #181c1f !important;
    border-color: #2d3237 !important;
    color: #e5e7eb !important;
}

.dark-mode .input-type-selector label:hover {
    background: #333a41 !important;
    border-color: #6366f1 !important;
}

.dark-mode .input-type-selector input:checked + span {
    color: #a5b4fc !important;
}

/* Text Areas */
.input-area textarea {
    width: 100%;
    min-height: 200px;
    padding: 15px;
    font-family: 'Consolas', 'Monaco', monospace;
    font-size: 0.9rem;
    background: #fff;
    border: 2px solid #e5e7eb;
    border-radius: 8px;
    color: #181818;
    resize: vertical;
    transition: border-color 0.3s ease;
}

.input-area textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

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

.dark-mode .input-area textarea {
    background: #181c1f !important;
    color: #e5e7eb !important;
    border-color: #2d3237 !important;
}

/* File Drop Zone */
.file-drop-zone {
    position: relative;
    border: 2px dashed #e5e7eb;
    border-radius: 12px;
    padding: 40px 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background: #f3f4f6;
}

.file-drop-zone:hover,
.file-drop-zone.dragover {
    border-color: var(--primary-color);
    background: rgba(99, 102, 241, 0.1);
}

.file-drop-zone input[type="file"] {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    cursor: pointer;
}

.drop-content .icon {
    font-size: 3rem;
    display: block;
    margin-bottom: 10px;
}

.drop-content p {
    color: #181818;
    font-size: 0.95rem;
    margin-bottom: 5px;
}

.drop-content small {
    color: var(--text-secondary);
}

.dark-mode .file-drop-zone {
    background: #23272b !important;
    border-color: #2d3237 !important;
}

.dark-mode .file-drop-zone:hover,
.dark-mode .file-drop-zone.dragover {
    background: rgba(99, 102, 241, 0.15) !important;
}

.dark-mode .drop-content p {
    color: #e5e7eb !important;
}

/* File Preview */
.file-preview {
    margin-top: 15px;
    padding: 15px;
    background: #f8fafc;
    border-radius: 8px;
    border: 1px solid #e5e7eb;
}

.dark-mode .file-preview {
    background: #181c1f !important;
    border-color: #2d3237 !important;
}

.file-preview .file-details {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
}

.file-preview .file-name {
    font-weight: 600;
    color: #181818;
}

.dark-mode .file-preview .file-name {
    color: #e5e7eb !important;
}

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

.file-preview .remove-file {
    padding: 5px 15px;
    background: var(--error-color);
    border: none;
    border-radius: 5px;
    color: white;
    cursor: pointer;
    font-size: 0.9rem;
}

/* Options Section */
.options-section {
    margin: 0 0 20px 0;
    padding: 15px 20px;
    background: #f8fafc;
    border-radius: 10px;
    border: 1px solid #e5e7eb;
}

.dark-mode .options-section {
    background: #181c1f !important;
    border-color: #2d3237 !important;
}

.options-section h3 {
    font-size: 1rem;
    margin-bottom: 12px;
    color: #181818;
    font-weight: 600;
}

.dark-mode .options-section h3 {
    color: #e5e7eb !important;
}

.options-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 10px;
}

.option-item {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    padding: 8px 14px;
    background: #fff;
    border: 2px solid #e5e7eb;
    border-radius: 6px;
    font-size: 0.85rem;
    color: #181818;
    font-weight: 500;
    transition: all 0.3s;
}

.option-item:hover {
    border-color: #6366f1;
    background: #e0e7ff;
}

.option-item input[type="checkbox"] {
    width: 16px;
    height: 16px;
    accent-color: #6366f1;
    cursor: pointer;
}

.dark-mode .option-item {
    background: #23272b !important;
    border-color: #2d3237 !important;
    color: #e5e7eb !important;
}

.dark-mode .option-item:hover {
    background: #333a41 !important;
    border-color: #6366f1 !important;
}

/* Action Button */
.action-btn {
    width: 100%;
    padding: 15px 30px;
    font-size: 1.1rem;
    font-weight: 600;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    border: none;
    border-radius: 10px;
    color: white;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-bottom: 20px;
}

.action-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(99, 102, 241, 0.3);
}

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

/* Output Section */
.output-section {
    background: #fff;
    border: 1px solid #e5e7eb;
    border-radius: 12px;
    padding: 20px;
    transition: background 0.3s, border-color 0.3s;
}

.dark-mode .output-section {
    background: #23272b !important;
    border-color: #2d3237 !important;
}

.output-section h2 {
    font-size: 1.2rem;
    margin-bottom: 15px;
    color: #181818;
    font-weight: 700;
}

.dark-mode .output-section h2 {
    color: #e5e7eb !important;
}

/* Stats Bar */
.stats-bar {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    padding: 12px;
    background: #f3f4f6;
    border-radius: 8px;
    margin-bottom: 15px;
    border: 1px solid #e5e7eb;
}

.dark-mode .stats-bar {
    background: #181c1f !important;
    border-color: #2d3237 !important;
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    background: #fff;
    border-radius: 6px;
    border: 1px solid #e5e7eb;
}

.dark-mode .stat-item {
    background: #23272b !important;
    border-color: #2d3237 !important;
}

.stat-label {
    font-size: 0.8rem;
    color: #64748b;
    font-weight: 500;
}

.dark-mode .stat-label {
    color: #94a3b8 !important;
}

.stat-value {
    font-size: 0.95rem;
    font-weight: 700;
    color: #6366f1;
}

.stat-value.additions {
    color: #16a34a;
}

.stat-value.deletions {
    color: #dc2626;
}

.dark-mode .stat-value {
    color: #a5b4fc !important;
}

.dark-mode .stat-value.additions {
    color: #4ade80 !important;
}

.dark-mode .stat-value.deletions {
    color: #f87171 !important;
}

/* Diff Output */
.diff-output {
    background: #f8fafc;
    border: 1px solid #e5e7eb;
    border-radius: 8px;
    min-height: 200px;
    max-height: 500px;
    overflow: auto;
    font-family: 'Consolas', 'Monaco', monospace;
    font-size: 0.85rem;
}

.dark-mode .diff-output {
    background: #181c1f !important;
    border-color: #2d3237 !important;
}

.diff-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 200px;
    color: #94a3b8;
    text-align: center;
    padding: 20px;
}

.diff-lines {
    padding: 10px 0;
}

.diff-line {
    display: flex;
    align-items: stretch;
    padding: 2px 10px;
    border-left: 3px solid transparent;
}

.diff-line.unchanged {
    background: transparent;
    border-left-color: transparent;
}

.diff-line.added {
    background: var(--diff-added-bg);
    border-left-color: #16a34a;
}

.diff-line.removed {
    background: var(--diff-removed-bg);
    border-left-color: #dc2626;
}

.dark-mode .diff-line.added {
    background: rgba(34, 197, 94, 0.15) !important;
    border-left-color: #4ade80 !important;
}

.dark-mode .diff-line.removed {
    background: rgba(239, 68, 68, 0.15) !important;
    border-left-color: #f87171 !important;
}

.line-nums {
    display: flex;
    gap: 5px;
    min-width: 60px;
    padding-right: 10px;
    color: #94a3b8;
    font-size: 0.8rem;
    user-select: none;
}

.line-num {
    min-width: 25px;
    text-align: right;
}

.diff-prefix {
    min-width: 20px;
    font-weight: 600;
    user-select: none;
}

.diff-line.added .diff-prefix {
    color: #16a34a;
}

.diff-line.removed .diff-prefix {
    color: #dc2626;
}

.diff-line.unchanged .diff-prefix {
    color: #94a3b8;
}

.dark-mode .diff-line.added .diff-prefix {
    color: #4ade80 !important;
}

.dark-mode .diff-line.removed .diff-prefix {
    color: #f87171 !important;
}

.diff-content {
    flex: 1;
    white-space: pre-wrap;
    word-break: break-all;
    color: #181818;
}

.dark-mode .diff-content {
    color: #e5e7eb !important;
}

.diff-line.added .diff-content {
    color: var(--diff-added-text);
}

.diff-line.removed .diff-content {
    color: var(--diff-removed-text);
}

.dark-mode .diff-line.added .diff-content {
    color: #4ade80 !important;
}

.dark-mode .diff-line.removed .diff-content {
    color: #f87171 !important;
}

/* Output Action Buttons */
.output-actions {
    display: flex;
    gap: 10px;
    margin-top: 15px;
    flex-wrap: wrap;
}

.copy-btn,
.download-btn,
.swap-btn,
.clear-btn {
    padding: 10px 20px;
    font-size: 0.9rem;
    font-weight: 500;
    border: 2px solid #e5e7eb;
    background: #f3f4f6;
    color: #181818;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.copy-btn:hover {
    border-color: var(--primary-color) !important;
    background: #e0e7ff !important;
}

.download-btn:hover {
    border-color: var(--secondary-color) !important;
    background: #d1fae5 !important;
}

.swap-btn:hover {
    border-color: #f59e0b !important;
    background: #fef3c7 !important;
}

.clear-btn:hover {
    border-color: #ef4444 !important;
    background: #fee2e2 !important;
}

.dark-mode .copy-btn,
.dark-mode .download-btn,
.dark-mode .swap-btn,
.dark-mode .clear-btn {
    background: #181c1f !important;
    color: #e5e7eb !important;
    border-color: #2d3237 !important;
}

.dark-mode .copy-btn:hover {
    border-color: var(--primary-color) !important;
    background: #333a41 !important;
}

.dark-mode .download-btn:hover {
    border-color: var(--secondary-color) !important;
    background: #333a41 !important;
}

.dark-mode .swap-btn:hover {
    border-color: #f59e0b !important;
    background: #333a41 !important;
}

.dark-mode .clear-btn:hover {
    border-color: #ef4444 !important;
    background: #333a41 !important;
}

.copy-btn.copied {
    background: #10b981 !important;
    border-color: #10b981 !important;
    color: white !important;
}

/* Status Messages */
.status {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    padding: 15px 30px;
    border-radius: 10px;
    font-weight: 500;
    z-index: 1000;
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from { opacity: 0; transform: translateX(-50%) translateY(20px); }
    to { opacity: 1; transform: translateX(-50%) translateY(0); }
}

.status.success {
    background: var(--success-color);
    color: white;
}

.status.error {
    background: var(--error-color);
    color: white;
}

.status.warning {
    background: var(--warning-color);
    color: white;
}

/* Hidden Class */
.hidden {
    display: none !important;
}

/* Visually Hidden */
.visually-hidden {
    position: absolute !important;
    height: 1px;
    width: 1px;
    overflow: hidden;
    clip: rect(1px, 1px, 1px, 1px);
    white-space: nowrap;
}

/* Topbar */
.topbar {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: 1.2rem;
    margin-top: 1.2rem;
    padding: 0 20px;
}

.github-link svg {
    width: 28px !important;
    height: 28px !important;
    display: block;
    color: #181818;
    fill: #181818;
    transition: color 0.2s, fill 0.2s;
}

.dark-mode .github-link svg {
    color: #fff !important;
    fill: #fff !important;
}

/* Theme Toggle */
.theme-toggle {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.theme-toggle-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0.2em;
    border-radius: 50%;
    background: none;
    border: none;
    cursor: pointer;
    transition: background 0.2s;
}

.theme-toggle-btn:focus {
    outline: none;
}

#theme-icon svg {
    width: 28px !important;
    height: 28px !important;
    display: block;
    color: #181818;
    fill: #181818;
    transition: color 0.2s, fill 0.2s;
}

.dark-mode #theme-icon svg {
    color: #fff !important;
    fill: #fff !important;
}

/* Client-side note */
.client-side-note {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-top: 10px;
    padding: 8px 16px;
    background: rgba(99, 102, 241, 0.1);
    border-radius: 8px;
    display: inline-block;
}

.dark-mode .client-side-note {
    background: rgba(99, 102, 241, 0.15);
    color: #a5b4fc;
}

/* Footer */
footer {
    color: #181818;
    background: transparent;
    text-align: center;
    padding: 30px 0 10px 0;
    font-size: 0.95rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 0.3em;
}

footer a {
    color: #6366f1;
    text-decoration: underline;
    font-weight: 600;
    transition: color 0.2s;
}

footer .copyright {
    color: #222;
    font-size: 0.98em;
    font-weight: 500;
    letter-spacing: 0.01em;
    margin-top: 0.5em;
    margin-bottom: 0;
    display: block;
}

.dark-mode footer {
    color: #e5e7eb !important;
}

.dark-mode footer a {
    color: #a5b4fc !important;
}

.dark-mode footer .copyright {
    color: #e5e7eb !important;
}

/* Dark Mode */
.dark-mode {
    background: #181c1f !important;
    color: #e5e7eb !important;
}

/* Responsive */
@media (max-width: 600px) {
    .options-grid {
        grid-template-columns: 1fr;
    }

    .stats-bar {
        flex-direction: column;
        gap: 8px;
    }

    .stat-item {
        justify-content: space-between;
    }

    header h1 {
        font-size: 2rem;
    }

    .container {
        padding: 10px;
    }
}