/* Modern CSS Variables */
:root {
    /* Modern color palette */
    --primary: #6366f1;
    --primary-light: #818cf8;
    --primary-dark: #4f46e5;
    --secondary: #8b5cf6;
    --accent: #06b6d4;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    
    /* Radius & Transitions (shared) */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* Dark Theme (default) */
[data-theme="dark"] {
    --bg-primary: #0f0f23;
    --bg-secondary: #1a1a2e;
    --bg-card: rgba(255, 255, 255, 0.03);
    --bg-glass: rgba(255, 255, 255, 0.05);
    --border-color: rgba(255, 255, 255, 0.1);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 8px 32px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.15);
    --bg-gradient: radial-gradient(ellipse at top, rgba(99, 102, 241, 0.1) 0%, transparent 50%),
                   radial-gradient(ellipse at bottom right, rgba(139, 92, 246, 0.08) 0%, transparent 50%);
}

/* Light Theme */
[data-theme="light"] {
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-card: rgba(255, 255, 255, 0.8);
    --bg-glass: rgba(255, 255, 255, 0.7);
    --border-color: rgba(0, 0, 0, 0.1);
    --text-primary: #1e293b;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 8px 32px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.15);
    --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.1);
    --bg-gradient: radial-gradient(ellipse at top, rgba(99, 102, 241, 0.05) 0%, transparent 50%),
                   radial-gradient(ellipse at bottom right, rgba(139, 92, 246, 0.04) 0%, transparent 50%);
}

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

/* Base */
body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-primary);
    background-image: var(--bg-gradient);
    background-attachment: fixed;
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    line-height: 1.6;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* Theme Toggle */
.theme-toggle {
    position: fixed;
    top: 1rem;
    right: 1rem;
    z-index: 200;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 0.75rem;
    background: var(--bg-glass);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-normal);
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.theme-toggle:hover {
    background: rgba(99, 102, 241, 0.1);
    border-color: var(--primary);
    color: var(--text-primary);
}

.theme-toggle .icon {
    font-size: 1.1rem;
    transition: transform var(--transition-normal);
}

.theme-toggle:hover .icon {
    transform: rotate(20deg);
}

/* Header */
header {
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    padding: 1.25rem 2rem;
    text-align: center;
    position: sticky;
    top: 0;
    z-index: 100;
}

header h1 {
    font-size: 1.75rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-light), var(--secondary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.02em;
}

header .subtitle {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-top: 0.25rem;
    font-weight: 400;
}

/* Main */
main {
    flex: 1;
    padding: 1.5rem;
    max-width: 1800px;
    margin: 0 auto;
    width: 100%;
}

/* Toolbar */
.toolbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
    padding: 1rem;
    background: var(--bg-glass);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.toolbar-left,
.toolbar-right {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

/* Modern Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.65rem 1.25rem;
    font-size: 0.875rem;
    font-weight: 500;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-normal);
    text-decoration: none;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(180deg, rgba(255,255,255,0.1) 0%, transparent 100%);
    opacity: 0;
    transition: opacity var(--transition-fast);
}

.btn:hover::before {
    opacity: 1;
}

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

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

.btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
    transform: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover:not(:disabled) {
    box-shadow: 0 6px 25px rgba(99, 102, 241, 0.4);
}

.btn-success {
    background: linear-gradient(135deg, var(--success), #059669);
    color: white;
    box-shadow: 0 4px 15px rgba(16, 185, 129, 0.3);
}

.btn-success:hover:not(:disabled) {
    box-shadow: 0 6px 25px rgba(16, 185, 129, 0.4);
}

.btn-info {
    background: linear-gradient(135deg, var(--accent), #0891b2);
    color: white;
    box-shadow: 0 4px 15px rgba(6, 182, 212, 0.3);
}

.btn-info:hover:not(:disabled) {
    box-shadow: 0 6px 25px rgba(6, 182, 212, 0.4);
}

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

.btn-secondary:hover:not(:disabled) {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
    border-color: rgba(255, 255, 255, 0.2);
}

.btn-preview {
    background: linear-gradient(135deg, var(--secondary), #7c3aed);
    color: white;
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.3);
}

.btn-preview:hover:not(:disabled) {
    box-shadow: 0 6px 25px rgba(139, 92, 246, 0.4);
}

.btn-readonly {
    background: linear-gradient(135deg, #ec4899, #f43f5e);
    color: white;
    box-shadow: 0 4px 15px rgba(236, 72, 153, 0.3);
}

.btn-readonly:hover:not(:disabled) {
    box-shadow: 0 6px 25px rgba(236, 72, 153, 0.4);
}

.btn.loading {
    opacity: 0.6;
    pointer-events: none;
}

/* Container */
.container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    height: calc(100vh - 280px);
    min-height: 450px;
}

/* Modern Panels */
.panel {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-sm);
}

.panel:hover {
    border-color: rgba(255, 255, 255, 0.15);
    box-shadow: var(--shadow-glow);
}

.panel-header {
    padding: 1rem 1.25rem;
    background: var(--bg-glass);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.panel-header h2 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: -0.01em;
}

/* Editor */
#markdown-input {
    flex: 1;
    padding: 1.25rem;
    border: none;
    resize: none;
    font-family: 'JetBrains Mono', 'Fira Code', 'Monaco', monospace;
    font-size: 0.9rem;
    line-height: 1.7;
    color: var(--text-primary);
    background: transparent;
    caret-color: var(--primary-light);
}

#markdown-input:focus {
    outline: none;
}

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

#markdown-input::selection {
    background: rgba(99, 102, 241, 0.3);
}

/* Preview */
.preview-content {
    flex: 1;
    padding: 1.25rem;
    overflow-y: auto;
    line-height: 1.7;
}

.preview-content::-webkit-scrollbar {
    width: 6px;
}

.preview-content::-webkit-scrollbar-track {
    background: transparent;
}

.preview-content::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 3px;
}

.preview-content::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.2);
}

.placeholder-text {
    color: var(--text-muted);
    font-style: italic;
}

/* Markdown Rendered Styles */
.preview-content h1,
.preview-content h2,
.preview-content h3,
.preview-content h4,
.preview-content h5,
.preview-content h6 {
    margin-top: 1.75rem;
    margin-bottom: 0.75rem;
    font-weight: 600;
    line-height: 1.3;
    color: var(--text-primary);
}

.preview-content h1 {
    font-size: 2rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
    background: linear-gradient(135deg, var(--text-primary), var(--text-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.preview-content h2 {
    font-size: 1.5rem;
    padding-bottom: 0.4rem;
    border-bottom: 1px solid var(--border-color);
}

.preview-content h3 { font-size: 1.25rem; }
.preview-content h4 { font-size: 1.1rem; }

.preview-content p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

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

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

.preview-content ul,
.preview-content ol {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
    color: var(--text-secondary);
}

.preview-content li {
    margin-bottom: 0.4rem;
}

.preview-content li::marker {
    color: var(--primary);
}

.preview-content blockquote {
    margin: 1.25rem 0;
    padding: 1rem 1.25rem;
    border-left: 3px solid var(--primary);
    background: var(--bg-glass);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    color: var(--text-secondary);
    font-style: italic;
}

.preview-content code {
    font-family: 'JetBrains Mono', 'Fira Code', monospace;
    font-size: 0.85em;
    padding: 0.2rem 0.5rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--accent);
}

.preview-content pre {
    margin: 1.25rem 0;
    padding: 1.25rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    overflow-x: auto;
}

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

.preview-content table {
    width: 100%;
    margin: 1.25rem 0;
    border-collapse: collapse;
    border-radius: var(--radius-md);
    overflow: hidden;
}

.preview-content th,
.preview-content td {
    padding: 0.875rem 1rem;
    border: 1px solid var(--border-color);
    text-align: left;
}

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

.preview-content td {
    color: var(--text-secondary);
}

.preview-content tr:hover td {
    background: var(--bg-glass);
}

.preview-content img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.preview-content hr {
    margin: 2rem 0;
    border: none;
    border-top: 1px solid var(--border-color);
}

/* Modern Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(8px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal.hidden {
    display: none;
}

.modal-content {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    width: 90%;
    max-width: 550px;
    box-shadow: var(--shadow-lg);
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from { 
        opacity: 0;
        transform: translateY(-20px) scale(0.95);
    }
    to { 
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.btn-close {
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    width: 32px;
    height: 32px;
    border-radius: var(--radius-sm);
    font-size: 1.25rem;
    cursor: pointer;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.btn-close:hover {
    background: rgba(239, 68, 68, 0.2);
    border-color: rgba(239, 68, 68, 0.3);
    color: var(--danger);
}

.modal-body {
    padding: 1.5rem;
}

.modal-body p {
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.share-link-container {
    display: flex;
    gap: 0.75rem;
    margin: 1rem 0;
}

.share-link-container input {
    flex: 1;
    padding: 0.875rem 1rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    color: var(--text-primary);
    font-family: 'JetBrains Mono', monospace;
}

.share-link-container input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.share-note {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 1rem;
    padding: 0.75rem;
    background: rgba(245, 158, 11, 0.1);
    border: 1px solid rgba(245, 158, 11, 0.2);
    border-radius: var(--radius-sm);
}

/* Mode Selector */
.mode-selector {
    margin-bottom: 1.25rem;
}

.mode-selector > label {
    display: block;
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
}

.mode-options {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.mode-option {
    display: block;
    cursor: pointer;
}

.mode-option input[type="radio"] {
    display: none;
}

.mode-label {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.875rem 1rem;
    background: var(--bg-glass);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.mode-option input[type="radio"]:checked + .mode-label {
    border-color: var(--primary);
    background: rgba(99, 102, 241, 0.1);
}

.mode-option:hover .mode-label {
    border-color: var(--primary-light);
    background: rgba(99, 102, 241, 0.05);
}

.mode-icon {
    font-size: 1.25rem;
    width: 2rem;
    text-align: center;
}

.mode-text {
    display: flex;
    flex-direction: column;
}

.mode-text strong {
    color: var(--text-primary);
    font-size: 0.9rem;
}

.mode-text small {
    color: var(--text-muted);
    font-size: 0.75rem;
}

/* Generate Button */
.btn-generate {
    width: 100%;
    padding: 0.875rem;
    font-size: 1rem;
    margin-bottom: 1rem;
}

/* Link Result */
.link-result {
    padding: 1rem;
    background: rgba(16, 185, 129, 0.1);
    border: 1px solid rgba(16, 185, 129, 0.2);
    border-radius: var(--radius-md);
    margin-bottom: 1rem;
}

.link-result.hidden {
    display: none;
}

.link-result p {
    color: var(--success);
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.link-result .share-link-container {
    margin: 0.75rem 0;
}

.link-result .expiration-info {
    margin-top: 0.75rem;
    margin-bottom: 0;
}

/* Expiration Selector */
.expiration-selector {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1.25rem;
    padding: 1rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
}

.expiration-selector label {
    color: var(--text-secondary);
    font-size: 0.9rem;
    white-space: nowrap;
}

.expiration-selector select {
    flex: 1;
    padding: 0.625rem 1rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-size: 0.875rem;
    font-family: inherit;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.expiration-selector select:hover {
    border-color: var(--primary);
}

.expiration-selector select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.expiration-info {
    font-size: 0.85rem;
    color: var(--accent);
    padding: 0.75rem;
    background: rgba(6, 182, 212, 0.1);
    border: 1px solid rgba(6, 182, 212, 0.2);
    border-radius: var(--radius-sm);
    margin-top: 0.75rem;
}

.expiration-info.hidden {
    display: none;
}

/* Expired Message */
.expired-message {
    text-align: center;
    padding: 3rem 2rem;
}

.expired-message h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.expired-message h2 {
    color: var(--danger);
    margin-bottom: 1rem;
    border: none;
    padding: 0;
}

.expired-message p {
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.expired-message .expired-date {
    font-family: 'JetBrains Mono', monospace;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.expired-message a {
    display: inline-block;
    margin-top: 1.5rem;
    padding: 0.75rem 1.5rem;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    border-radius: var(--radius-md);
    font-weight: 500;
    text-decoration: none;
    transition: all var(--transition-normal);
}

.expired-message a:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(99, 102, 241, 0.4);
}

/* Modern Toast */
.toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.875rem 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    z-index: 1001;
    animation: toastIn 0.4s ease;
    backdrop-filter: blur(10px);
}

.toast.hidden {
    display: none;
}

@keyframes toastIn {
    from {
        opacity: 0;
        transform: translate(-50%, 20px);
    }
    to {
        opacity: 1;
        transform: translate(-50%, 0);
    }
}

/* Footer */
footer {
    text-align: center;
    padding: 1.25rem;
    background: var(--bg-glass);
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
    font-size: 0.8rem;
}

footer a {
    color: var(--primary-light);
    text-decoration: none;
    transition: color var(--transition-fast);
}

footer a:hover {
    color: var(--accent);
}

/* Preview Mode */
body.preview-mode .toolbar {
    display: none;
}

body.preview-mode .editor-panel {
    display: none;
}

body.preview-mode .container {
    grid-template-columns: 1fr;
    max-width: 900px;
    margin: 0 auto;
}

body.preview-mode .preview-panel {
    min-height: calc(100vh - 200px);
}

body.preview-mode .back-button {
    display: block !important;
}

.back-button {
    text-align: center;
    margin-bottom: 1rem;
}

.back-button.hidden {
    display: none;
}

/* Responsive */
@media (max-width: 768px) {
    .toolbar {
        flex-direction: column;
        align-items: stretch;
        gap: 0.75rem;
    }

    .toolbar-left,
    .toolbar-right {
        justify-content: center;
    }

    header h1 {
        font-size: 1.5rem;
    }

    .btn {
        padding: 0.6rem 1rem;
        font-size: 0.8rem;
    }
}

@media (max-width: 480px) {
    main {
        padding: 1rem;
    }

    header {
        padding: 1rem;
    }

    .toolbar {
        padding: 0.75rem;
        margin-bottom: 1rem;
    }

    .toolbar-right {
        flex-wrap: wrap;
    }

    .btn {
        flex: 1;
        min-width: 100px;
    }

    .theme-toggle {
        top: 0.75rem;
        left: 0.75rem;
        padding: 0.4rem 0.6rem;
        font-size: 0.75rem;
    }
}

/* Print Styles */
@media print {
    body {
        background: white !important;
        color: black !important;
    }
    
    header, footer, .toolbar, .back-button {
        display: none !important;
    }
    
    .container {
        display: block !important;
    }
    
    .panel {
        border: none !important;
        box-shadow: none !important;
        background: white !important;
    }
    
    .preview-content {
        color: black !important;
    }
    
    .preview-content h1,
    .preview-content h2,
    .preview-content h3,
    .preview-content h4,
    .preview-content h5,
    .preview-content h6 {
        color: black !important;
        -webkit-text-fill-color: black !important;
        background: none !important;
    }
    
    .preview-content p,
    .preview-content li,
    .preview-content td {
        color: #333 !important;
    }
    
    .preview-content a {
        color: #0066cc !important;
    }
    
    .preview-content code {
        background: #f5f5f5 !important;
        border-color: #ddd !important;
        color: #333 !important;
    }
    
    .preview-content pre {
        background: #f5f5f5 !important;
        border-color: #ddd !important;
    }
    
    .preview-content blockquote {
        background: #f9f9f9 !important;
        border-left-color: #666 !important;
    }
    
    .preview-content p,
    .preview-content li,
    .preview-content pre,
    .preview-content blockquote,
    .preview-content table {
        break-inside: avoid;
    }
    
    .preview-content h1,
    .preview-content h2,
    .preview-content h3,
    .preview-content h4,
    .preview-content h5,
    .preview-content h6 {
        break-after: avoid;
    }
}