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

:root {
    /* Color Palette */
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --primary-light: #dbeafe;
    --secondary-color: #8b5cf6;
    --secondary-hover: #7c3aed;
    --success-color: #10b981;
    --error-color: #ef4444;
    --warning-color: #f59e0b;
    
    /* Neutral Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --border-color: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-tertiary: #94a3b8;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background: #f8fafc;
    min-height: 100vh;
    color: var(--text-primary);
    line-height: 1.6;
}

/* Container */
.container {
    max-width: 1600px;
    margin: 0 auto;
    padding: var(--spacing-xl);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background: var(--bg-primary);
    box-shadow: 0 0 50px rgba(0, 0, 0, 0.05);
}

/* Header */
.header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-xl) 0;
    background: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    color: white;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
}

.logo-icon {
    width: 72px;
    height: 72px;
    filter: drop-shadow(0 4px 8px rgba(255, 255, 255, 0.3));
    animation: logoFloat 3s ease-in-out infinite;
}

@keyframes logoFloat {
    0%, 100% {
        transform: translateY(0px);
    }
    50% {
        transform: translateY(-5px);
    }
}

.logo-icon svg {
    width: 100%;
    height: 100%;
}

.logo-text {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.logo-tagline {
    font-size: 0.875rem;
    color: rgba(255, 255, 255, 0.9);
    font-weight: 400;
    letter-spacing: 2px;
    text-transform: uppercase;
    margin: 0;
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin: 0;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.subtitle {
    font-size: 1.125rem;
    opacity: 0.95;
    font-weight: 400;
}

/* Toolbar */
.toolbar {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.toolbar-left {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.toolbar-right {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: 0.625rem 1.25rem;
    font-size: 0.9375rem;
    font-weight: 500;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: inherit;
    white-space: nowrap;
}

.btn-icon {
    width: 18px;
    height: 18px;
}

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

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

.btn-secondary {
    background: var(--secondary-color);
    color: white;
    box-shadow: var(--shadow-sm);
}

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

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

.btn-outline:hover {
    background: var(--bg-tertiary);
    border-color: var(--text-tertiary);
    transform: translateY(-1px);
}

.btn-small {
    padding: 0.375rem 0.875rem;
    font-size: 0.875rem;
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-weight: 500;
}

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

/* Indent Control */
.indent-control {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.9375rem;
    color: var(--text-secondary);
}

.indent-control select {
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 0.9375rem;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.indent-control select:hover {
    border-color: var(--primary-color);
}

.indent-control select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--primary-light);
}

/* Content Area */
.content {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: var(--spacing-lg);
    flex: 1;
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-xl);
    min-height: 600px;
}

/* Divider */
.divider {
    width: 2px;
    background: linear-gradient(to bottom, transparent, var(--border-color), transparent);
    position: relative;
}

.divider::before {
    content: '→';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: var(--bg-primary);
    color: var(--text-tertiary);
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--border-color);
    font-size: 1.25rem;
}

/* Editor Panel */
.editor-panel {
    display: flex;
    flex-direction: column;
    min-width: 0;
    flex: 1;
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--border-color);
}

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

.header-buttons {
    display: flex;
    gap: var(--spacing-sm);
}

.status-indicator {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.875rem;
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--text-tertiary);
    animation: pulse 2s ease-in-out infinite;
}

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

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

.status-indicator.processing .status-dot {
    background: var(--warning-color);
}

@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.status-text {
    color: var(--text-secondary);
    font-weight: 500;
}

/* Editor Wrapper */
.editor-wrapper {
    position: relative;
    flex: 1;
    min-width: 0;
    min-height: 400px;
    display: flex;
    flex-direction: row;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    overflow: hidden;
    background: var(--bg-secondary);
    transition: border-color var(--transition-fast);
}

.editor-wrapper:focus-within {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--primary-light);
}

/* Line Numbers */
.line-numbers {
    background: var(--bg-tertiary);
    color: var(--text-tertiary);
    padding: var(--spacing-md);
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
    font-size: 0.875rem;
    line-height: 1.6;
    text-align: right;
    user-select: none;
    border-right: 1px solid var(--border-color);
    min-width: 48px;
    max-width: 60px;
    overflow: hidden;
    white-space: pre;
    flex-shrink: 0;
}

/* Editor */
.editor {
    flex: 1;
    min-width: 0;
    padding: var(--spacing-md);
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
    font-size: 0.875rem;
    line-height: 1.6;
    border: none;
    outline: none;
    resize: none;
    background: var(--bg-secondary);
    color: var(--text-primary);
    overflow: auto;
    white-space: pre;
    overflow-wrap: normal;
}

.editor::placeholder {
    color: var(--text-tertiary);
}

.output-editor {
    background: #282c34;
    color: #abb2bf;
    cursor: default;
    white-space: pre;
    overflow-wrap: normal;
    min-width: 0;
    flex: 1;
}

/* Syntax Highlighting for Output */
.output-editor .xml-tag {
    color: #e06c75;
}

.output-editor .xml-attr-name {
    color: #d19a66;
}

.output-editor .xml-attr-value {
    color: #98c379;
}

.output-editor .xml-comment {
    color: #5c6370;
    font-style: italic;
}

.output-editor .xml-text {
    color: #abb2bf;
}

.output-editor .xml-declaration {
    color: #c678dd;
}

/* Panel Footer */
.panel-footer {
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color);
}

.stats {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* Toast Notification */
.toast {
    position: fixed;
    bottom: -100px;
    right: var(--spacing-xl);
    background: var(--text-primary);
    color: white;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    transition: bottom var(--transition-normal);
    z-index: 1000;
    font-weight: 500;
}

.toast.show {
    bottom: var(--spacing-xl);
}

.toast-icon {
    width: 24px;
    height: 24px;
}

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

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

/* XML Introduction Section */
.intro-section {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-2xl);
    margin-top: var(--spacing-2xl);
    box-shadow: var(--shadow-md);
}

.intro-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 3px solid var(--primary-color);
}

.intro-icon {
    width: 40px;
    height: 40px;
    color: var(--primary-color);
}

.intro-header h2 {
    font-size: 1.875rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
}

.intro-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-lg);
}

.intro-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
}

.intro-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}

.intro-card h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: 0 0 var(--spacing-md) 0;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.intro-card p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin: 0;
}

.intro-card ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.intro-card li {
    color: var(--text-secondary);
    line-height: 1.8;
    padding-left: var(--spacing-lg);
    position: relative;
    margin-bottom: var(--spacing-sm);
}

.intro-card li::before {
    content: '▸';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

.code-example {
    background: #282c34;
    border-radius: var(--radius-sm);
    overflow: hidden;
    margin-top: var(--spacing-md);
}

.code-example pre {
    margin: 0;
    padding: var(--spacing-md);
    overflow-x: auto;
}

.code-example code {
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
    font-size: 0.875rem;
    line-height: 1.6;
    color: #abb2bf;
}

.comparison {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.comparison-item {
    background: var(--bg-tertiary);
    padding: var(--spacing-md);
    border-radius: var(--radius-sm);
}

.comparison-item strong {
    color: var(--text-primary);
    display: block;
    margin-bottom: var(--spacing-sm);
}

.comparison-item ul {
    list-style: none;
    padding: 0;
    margin: var(--spacing-sm) 0 0 0;
}

.comparison-item li {
    color: var(--text-secondary);
    font-size: 0.875rem;
    line-height: 1.6;
    padding-left: var(--spacing-md);
    margin-bottom: var(--spacing-xs);
}

.comparison-item li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--success-color);
    font-weight: bold;
}

.highlight-card {
    background: linear-gradient(135deg, #dbeafe 0%, #eff6ff 100%);
    border-color: var(--primary-color);
    grid-column: 1 / -1;
}

.highlight-card h3 {
    color: var(--primary-color);
}

/* Footer */
.footer {
    text-align: center;
    margin-top: var(--spacing-xl);
    padding: var(--spacing-xl) 0;
    color: var(--text-secondary);
    font-size: 0.875rem;
    border-top: 1px solid var(--border-color);
}

/* Responsive Design */
@media (max-width: 1200px) {
    .content {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }
    
    .divider {
        display: none;
    }
    
    .header h1 {
        font-size: 2rem;
    }
}

@media (max-width: 768px) {
    .container {
        padding: var(--spacing-md);
    }
    
    .header h1 {
        font-size: 1.75rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .toolbar {
        padding: var(--spacing-md);
    }
    
    .toolbar-left,
    .toolbar-right {
        width: 100%;
    }
    
    .btn {
        flex: 1;
        justify-content: center;
    }
    
    .content {
        padding: var(--spacing-md);
    }
    
    .toast {
        right: var(--spacing-md);
        left: var(--spacing-md);
    }
    
    .toast.show {
        bottom: var(--spacing-md);
    }
    
    .intro-section {
        padding: var(--spacing-lg);
    }
    
    .intro-header h2 {
        font-size: 1.5rem;
    }
    
    .intro-content {
        grid-template-columns: 1fr;
    }
    
    .comparison {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .logo {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .logo-icon {
        width: 60px;
        height: 60px;
    }
    
    .logo-text {
        align-items: center;
        text-align: center;
    }
    
    .header h1 {
        font-size: 1.5rem;
    }
    
    .logo-tagline {
        font-size: 0.75rem;
        letter-spacing: 1px;
    }
    
    .btn {
        font-size: 0.875rem;
        padding: 0.5rem 1rem;
    }
}

/* Scrollbar Styling */
.editor::-webkit-scrollbar,
.line-numbers::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

.editor::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
}

.editor::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: var(--radius-sm);
}

.editor::-webkit-scrollbar-thumb:hover {
    background: var(--text-tertiary);
}

.output-editor::-webkit-scrollbar-track {
    background: #21252b;
}

.output-editor::-webkit-scrollbar-thumb {
    background: #4b5263;
    border-radius: var(--radius-sm);
}

.output-editor::-webkit-scrollbar-thumb:hover {
    background: #5c6370;
}

/* Loading Animation */
@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.processing .btn-icon {
    animation: spin 1s linear infinite;
}