/* CSS Variables */
:root {
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --secondary-color: #6b7280;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;

    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;

    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-muted: #9ca3af;

    --border-color: #e5e7eb;
    --border-hover: #d1d5db;

    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);

    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;

    --font-mono: 'Courier New', monospace;
}

/* Dark Theme */
[data-theme="dark"] {
    --bg-primary: #1f2937;
    --bg-secondary: #111827;
    --bg-tertiary: #0f172a;

    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --text-muted: #9ca3af;

    --border-color: #374151;
    --border-hover: #4b5563;
}

/* Reset & Base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: all 0.3s ease;
}

.container {
    max-width: 100vw;
    height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.header {
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow-sm);
}

.header-left {
    display: flex;
    align-items: center;
}

.header-left h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    display: flex;
    gap: 5px;
}

.header-left i {
    margin-right: 0.5rem;
}

.header-right {
    display: flex;
    gap: 0.75rem;
    align-items: center;
}

/* Buttons */
.btn {
    padding: 0.5rem;
    border: none;
    border-radius: var(--radius-md);
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
}

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

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

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

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

.theme-toggle {
    padding: 0.5rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all 0.2s ease;
    color: var(--text-primary);
}

.theme-toggle:hover {
    background: var(--border-color);
    transform: translateY(-1px);
}

/* Mode Toggle */
.mode-toggle {
    padding: 1rem 2rem;
    display: flex;
    justify-content: center;
    gap: 0.5rem;
}

.mode-btn {
    padding: 0.5rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all 0.2s ease;
    color: var(--text-secondary);
    font-weight: 500;
}

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

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

.mode-btn i {
    margin: 0rem;
}

/* Main Content */
.main-content {
    flex: 1;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1px;
    background: var(--border-color);
    overflow: hidden;
}

.main-content.editor-only {
    grid-template-columns: 1fr;
}

.main-content.preview-only {
    grid-template-columns: 1fr;
}

.main-content.editor-only .preview-panel,
.main-content.preview-only .editor-panel {
    display: none;
}

/* Editor Panel */
.editor-panel {
    background: var(--bg-primary);
    display: flex;
    flex-direction: column;
}

.toolbar {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 0.75rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.toolbar-group {
    display: flex;
    gap: 0.25rem;
    padding-right: 0.75rem;
    border-right: 1px solid var(--border-color);
}

.toolbar-group:last-child {
    border-right: none;
}

.tool-btn {
    padding: 0.5rem;
    background: transparent;
    border: 1px solid transparent;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.2s ease;
    color: var(--text-secondary);
    font-weight: 600;
    min-width: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

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

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

/* Editor Textarea */
#editor {
    flex: 1;
    padding: 1.5rem;
    border: none;
    outline: none;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-mono);
    font-size: 0.875rem;
    line-height: 1.6;
    resize: none;
    tab-size: 2;
}

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

/* Quick Help */
.quick-help {
    background: linear-gradient(135deg, #dbeafe 0%, #bfdbfe 100%);
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--border-color);
}

[data-theme="dark"] .quick-help {
    background: linear-gradient(135deg, #1e3a8a 0%, #1e40af 100%);
}

.quick-help h3 {
    color: #1e40af;
    margin-bottom: 0.75rem;
    font-size: 0.875rem;
    font-weight: 600;
}

[data-theme="dark"] .quick-help h3 {
    color: #93c5fd;
}

.help-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 0.5rem;
    font-size: 0.75rem;
}

.help-grid code {
    background: rgba(59, 130, 246, 0.1);
    padding: 0.125rem 0.25rem;
    border-radius: var(--radius-sm);
    font-family: var(--font-mono);
    color: #1e40af;
}

[data-theme="dark"] .help-grid code {
    color: #93c5fd;
}

/* Preview Panel */
.preview-panel {
    background: var(--bg-primary);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.preview-panel h2 {
    padding: 0.888rem 0;
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
}

.preview-panel h2.title {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 0.888rem 1.5rem;
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
}

.preview-panel h2 i {
    margin-right: 0.5rem;
    color: var(--primary-color);
}

.preview-content {
    flex: 1;
    padding: 1.5rem;
    overflow-y: auto;
    line-height: 1.7;
}

/* Markdown Styles */
.preview-content h1,
.preview-content h2,
.preview-content h3,
.preview-content h4,
.preview-content h5,
.preview-content h6 {
    margin: 0.75rem 0 1rem 0;
    font-weight: 700;
    line-height: 1.3;
    color: var(--text-primary);
}

.preview-content h1 {
    font-size: 2rem;
    padding-bottom: 0.5rem;
}

.preview-content h2 {
    font-size: 1.4rem;
    padding-bottom: 0.2rem;
}


.preview-content h3 {
    font-size: 1.3rem;
}

.preview-content p {
    margin: 0;
    color: var(--text-primary);
}

.preview-content strong {
    font-weight: 700;
    color: var(--text-primary);
}

.preview-content em {
    font-style: italic;
    padding: .1em .2em;
    border-radius: 2px;
    background-color: var(--warning-color);
}

.preview-content em.warning {
    font-style: italic;
    padding: 20px;
    border-radius: 6px;
    background-color: var(--warning-color);
}

.preview-content ul,
.preview-content ol {
    margin: 1rem 0;
    padding-left: 2rem;
}

.preview-content li {
    margin: 0.5rem 0;
}

.preview-content blockquote {
    margin: 1.5rem 0;
    padding: 1rem 1.5rem;
    background: var(--bg-secondary);
    border-left: 4px solid var(--primary-color);
    font-style: italic;
    color: var(--text-secondary);
}

.preview-content code {
    background: var(--bg-secondary);
    padding: 0.125rem 0.375rem;
    border-radius: var(--radius-sm);
    font-family: var(--font-mono);
    font-size: 0.875em;
    color: var(--danger-color);
}

.preview-content pre {
    background: var(--bg-secondary);
    padding: 1rem;
    border-radius: var(--radius-md);
    overflow-x: auto;
    margin: 1rem 0;
    border: 1px solid var(--border-color);
}

.preview-content pre code {
    background: none;
    padding: 0;
    color: var(--text-primary);
}

.preview-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    border: 1px solid var(--border-color);
    overflow: hidden;
}

.preview-content th,
.preview-content td {
    padding: 0.5rem 0.75rem;
    text-align: left;
    border: 1px solid var(--border-color);
}

.preview-content th {
    background: var(--bg-secondary);
    font-weight: 600;
    color: var(--text-primary);
}

.preview-content img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    margin: 1rem 0;
}

.preview-content a {
    color: var(--primary-color);
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: border-color 0.2s ease;
}

.preview-content a:hover {
    border-bottom-color: var(--primary-color);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    backdrop-filter: blur(4px);
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    width: 90%;
    max-width: 500px;
    max-height: 80vh;
    overflow: hidden;
    animation: modalSlideIn 0.3s ease;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: translateY(-20px) scale(0.95);
    }

    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

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

.modal-header h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
}

.close-btn {
    background: none;
    border: none;
    font-size: 1.25rem;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 0.25rem;
    border-radius: var(--radius-sm);
    transition: all 0.2s ease;
}

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

.modal-body {
    padding: 1.5rem;
}

.modal-footer {
    padding: 1.5rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
    gap: 0.75rem;
}

/* Tabs */
.tabs {
    display: flex;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.tab-btn {
    padding: 0.75rem 1rem;
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    cursor: pointer;
    color: var(--text-secondary);
    font-weight: 500;
    transition: all 0.2s ease;
}

.tab-btn:hover {
    color: var(--text-primary);
}

.tab-btn.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* Upload Area */
.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: var(--radius-lg);
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s ease;
    margin-bottom: 1rem;
}

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

.upload-area i {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.upload-area p {
    color: var(--text-secondary);
    margin: 0;
}

/* Image Preview */
.image-preview {
    text-align: center;
    margin-top: 1rem;
}

.image-preview img {
    max-width: 100%;
    max-height: 200px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    margin-bottom: 1rem;
}

/* Input */
.input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 0.875rem;
    transition: border-color 0.2s ease;
    margin-bottom: 1rem;
}

.input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

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

/* Responsive */
@media (max-width: 768px) {
    .header {
        padding: 1rem;
        flex-direction: column;
        gap: 1rem;
    }

    .header-right {
        width: 100%;
        justify-content: center;
    }

    .mode-toggle {
        padding: 1rem;
    }

    .main-content {
        grid-template-columns: 1fr;
    }

    .toolbar {
        padding: 0.5rem;
    }

    .toolbar-group {
        padding-right: 0.5rem;
    }

    #editor {
        padding: 1rem;
        font-size: 0.8rem;
    }

    .preview-content {
        padding: 1rem;
    }

    .help-grid {
        grid-template-columns: 1fr;
        font-size: 0.7rem;
    }

    .modal-content {
        width: 95%;
        margin: 1rem;
    }

    .modal-header,
    .modal-body,
    .modal-footer {
        padding: 1rem;
    }
}

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

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

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

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

/* Loading Animation */
.loading {
    display: inline-block;
    width: 1rem;
    height: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Success/Error Messages */
.message {
    padding: 0.75rem 1rem;
    border-radius: var(--radius-md);
    margin: 1rem 0;
    font-weight: 500;
}

.message.success {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success-color);
    border: 1px solid rgba(16, 185, 129, 0.2);
}

.message.error {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger-color);
    border: 1px solid rgba(239, 68, 68, 0.2);
}

/* Animations */
.fade-in {
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

.slide-up {
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from {
        transform: translateY(20px);
        opacity: 0;
    }

    to {
        transform: translateY(0);
        opacity: 1;
    }
}