:root {
    /* Modern color palette */
    --primary-color: #667eea;
    --primary-dark: #5a67d8;
    --primary-light: #7c3aed;
    --secondary-color: #4fd1c7;
    --accent-color: #f093fb;
    --success-color: #48bb78;
    --warning-color: #ed8936;
    --danger-color: #f56565;
    
    /* Background gradients and surfaces */
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --surface-gradient: linear-gradient(145deg, #ffffff 0%, #f7fafc 100%);
    --card-bg: rgba(255, 255, 255, 0.95);
    --glass-bg: rgba(255, 255, 255, 0.25);
    --glass-border: rgba(255, 255, 255, 0.18);
    
    /* Text colors */
    --text-primary: #2d3748;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    --text-inverse: #ffffff;
    
    /* Shadows */
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --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);
    
    /* Modern 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;
    --radius-full: 9999px;
}

* {
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    margin: 0;
    padding: 0;
    background: var(--bg-gradient);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Header */
header {
    background: var(--glass-bg);
    backdrop-filter: blur(20px) saturate(180%);
    border-bottom: 1px solid var(--glass-border);
    padding: var(--spacing-lg) var(--spacing-xl);
    position: sticky;
    top: 0;
    z-index: 100;
}

header h1 {
    margin: 0;
    font-size: 1.875rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-align: center;
}

main {
    display: flex;
    min-height: calc(100vh - 140px);
    gap: var(--spacing-lg);
    padding: var(--spacing-lg);
}

/* Modern Left Panel */
.left-panel {
    width: 280px;
    background: var(--glass-bg);
    backdrop-filter: blur(20px) saturate(180%);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-lg);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    flex-shrink: 0;
}

.nav-button {
    background: transparent;
    border: none;
    padding: var(--spacing-md) var(--spacing-lg);
    text-align: left;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: var(--radius-lg);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

.nav-button::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
    transition: left 0.5s ease;
}

.nav-button:hover::before {
    left: 100%;
}

.nav-button:hover {
    background: rgba(102, 126, 234, 0.1);
    color: var(--primary-color);
    transform: translateX(4px);
}

.nav-button.active {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: var(--text-inverse);
    box-shadow: var(--shadow-md);
    transform: translateX(4px);
}

/* Content Area */
.content-area {
    flex: 1;
    background: var(--card-bg);
    backdrop-filter: blur(20px) saturate(180%);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-lg);
    overflow-y: auto;
    min-width: 0;
}

.tab-content {
    display: none;
    animation: fadeIn 0.3s ease-in-out;
}

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

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Typography */
h2 {
    font-size: 1.875rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0 0 var(--spacing-lg) 0;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: var(--spacing-lg) 0 var(--spacing-md) 0;
}

h4 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin: var(--spacing-md) 0 var(--spacing-sm) 0;
}

/* Modern Form Elements */
label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

input[type="text"],
input[type="number"],
textarea,
select {
    width: 100%;
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    border: 2px solid rgba(102, 126, 234, 0.1);
    border-radius: var(--radius-lg);
    font-size: 0.95rem;
    background: rgba(255, 255, 255, 0.8);
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

input[type="text"]:focus,
input[type="number"]:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
    background: rgba(255, 255, 255, 1);
}

/* Modern Buttons */
.button {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: var(--text-inverse);
    padding: var(--spacing-md) var(--spacing-xl);
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    margin-right: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
}

.button::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
    transition: left 0.5s ease;
}

.button:hover::before {
    left: 100%;
}

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

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

.button-small {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.875rem;
    margin-right: var(--spacing-sm);
}

.reset-button {
    background: linear-gradient(135deg, var(--danger-color), #e53e3e);
}

/* File Upload Area */
.file-upload-area,
.paste-area {
    border: 2px dashed rgba(102, 126, 234, 0.3);
    padding: var(--spacing-2xl);
    text-align: center;
    margin-bottom: var(--spacing-lg);
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-xl);
    transition: all 0.3s ease;
}

.file-upload-area:hover,
#drop-area.highlight {
    border-color: var(--primary-color);
    background: rgba(102, 126, 234, 0.05);
    transform: translateY(-2px);
}

#csv-file-input {
    display: none;
}

/* Config Sections */
.config-section {
    background: var(--surface-gradient);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(102, 126, 234, 0.1);
}

/* Tables */
.preview-table,
#csv-preview table {
    width: 100%;
    border-collapse: collapse;
    margin: var(--spacing-md) 0;
    background: white;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.preview-table th,
.preview-table td,
#csv-preview th,
#csv-preview td {
    padding: var(--spacing-md);
    text-align: left;
    border-bottom: 1px solid rgba(102, 126, 234, 0.1);
}

.preview-table th,
#csv-preview th {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: var(--text-inverse);
    font-weight: 600;
    font-size: 0.875rem;
}

.preview-table tr:hover,
#csv-preview tr:hover {
    background: rgba(102, 126, 234, 0.05);
}

/* Column Mapping */
.column-mapping-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
    padding: var(--spacing-xl);
    border: 1px solid rgba(102, 126, 234, 0.1);
    border-radius: var(--radius-xl);
    background: var(--surface-gradient);
    margin-bottom: var(--spacing-md);
    box-shadow: var(--shadow-sm);
}

.column-mapping-row:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-1px);
    transition: all 0.3s ease;
}

/* Prefix Entry */
.prefix-entry {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    align-items: end;
}

.prefix-entry input {
    margin-bottom: 0;
    flex: 1;
}

/* Graph Container */
.graph-container {
    background: white;
    border: 1px solid rgba(102, 126, 234, 0.1);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    height: 600px;
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    margin: var(--spacing-lg) 0;
}

#rdf-graph {
    width: 100%;
    height: 100%;
    border-radius: var(--radius-lg);
}

/* Chart Controls */
.chart-controls {
    background: var(--surface-gradient);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(102, 126, 234, 0.1);
    margin: var(--spacing-lg) 0;
}

.button-group {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.chart-btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border: 1px solid rgba(102, 126, 234, 0.2);
    border-radius: var(--radius-full);
    background: white;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
    font-size: 0.875rem;
}

.chart-btn:hover {
    background: rgba(102, 126, 234, 0.1);
    border-color: var(--primary-color);
    transform: translateY(-1px);
}

.chart-btn.active {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: white;
    border-color: var(--primary-color);
    box-shadow: var(--shadow-sm);
}

/* Radio Groups */
.radio-group {
    display: flex;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-sm);
}

.radio-group label {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    cursor: pointer;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-lg);
    transition: all 0.3s ease;
}

.radio-group label:hover {
    background: rgba(102, 126, 234, 0.05);
}

.radio-group input[type="radio"] {
    margin: 0;
    cursor: pointer;
    accent-color: var(--primary-color);
}

/* Object Type Selector */
.object-type-selector {
    background: var(--surface-gradient);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    border: 1px solid rgba(102, 126, 234, 0.1);
    box-shadow: var(--shadow-sm);
    margin: var(--spacing-lg) 0;
}

/* Code/Text Areas */
#rdf-output-editor,
#sparql-query-input {
    width: 100%;
    min-height: 400px;
    font-family: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
    background: #1a202c;
    color: #e2e8f0;
    border: 1px solid rgba(102, 126, 234, 0.2);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    line-height: 1.5;
    font-size: 0.875rem;
}

#sparql-query-input {
    min-height: 200px;
}

/* SPARQL Results */
#sparql-results {
    background: white;
    border: 1px solid rgba(102, 126, 234, 0.1);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-top: var(--spacing-md);
    box-shadow: var(--shadow-sm);
    overflow-x: auto;
}

#sparql-results table {
    width: 100%;
    border-collapse: collapse;
    border-radius: var(--radius-lg);
    overflow: hidden;
}

#sparql-results th,
#sparql-results td {
    padding: var(--spacing-md);
    text-align: left;
    border-bottom: 1px solid rgba(102, 126, 234, 0.1);
}

#sparql-results th {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: white;
    font-weight: 600;
}

/* Bottom Bar */
.bottom-bar {
    background: var(--glass-bg);
    backdrop-filter: blur(20px) saturate(180%);
    border-top: 1px solid var(--glass-border);
    padding: var(--spacing-lg) var(--spacing-xl);
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

/* Progress Bar */
#progress-bar {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    z-index: 9999;
    background: linear-gradient(90deg, var(--primary-color), var(--primary-light));
    box-shadow: 0 0 10px rgba(102, 126, 234, 0.5);
}

/* Graph Message */
#graph-message {
    margin-bottom: var(--spacing-lg);
    color: var(--text-muted);
    text-align: center;
    font-style: italic;
}

/* Filter Group */
.filter-group {
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 1px solid rgba(102, 126, 234, 0.1);
}

.filter-group select {
    margin-bottom: 0;
    width: auto;
    min-width: 200px;
}

/* Node and Link Styles */
.node circle {
    stroke: var(--primary-color);
    stroke-width: 2px;
    cursor: pointer;
    fill: white;
    filter: drop-shadow(2px 2px 4px rgba(0,0,0,0.1));
    transition: all 0.3s ease;
}

.node circle:hover {
    stroke-width: 3px;
    filter: drop-shadow(3px 3px 6px rgba(0,0,0,0.2));
}

.link {
    stroke: var(--text-muted);
    stroke-opacity: 0.8;
    stroke-width: 2px;
    transition: all 0.3s ease;
}

.link:hover {
    stroke: var(--primary-color);
    stroke-width: 3px;
}

.node text {
    font-size: 11px;
    pointer-events: none;
    text-anchor: middle;
    fill: var(--text-primary);
    font-weight: 500;
}

.link-label {
    font-size: 9px;
    fill: var(--text-secondary);
    text-anchor: middle;
    font-weight: 500;
}

.node.highlighted circle {
    stroke: var(--secondary-color);
    stroke-width: 4px;
    filter: drop-shadow(0 0 8px rgba(79, 209, 199, 0.5));
}

.link.highlighted {
    stroke: var(--secondary-color);
    stroke-width: 4px;
}

/* Responsive Design */
@media (max-width: 1024px) {
    main {
        flex-direction: column;
        gap: var(--spacing-md);
        padding: var(--spacing-md);
    }
    
    .left-panel {
        width: 100%;
        flex-direction: row;
        overflow-x: auto;
        padding: var(--spacing-md);
    }
    
    .nav-button {
        flex-shrink: 0;
        white-space: nowrap;
    }
    
    .content-area {
        padding: var(--spacing-lg);
    }
}

@media (max-width: 768px) {
    header h1 {
        font-size: 1.5rem;
    }
    
    .column-mapping-row {
        grid-template-columns: 1fr;
    }
    
    .radio-group {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .button-group {
        flex-direction: column;
    }
    
    .chart-btn {
        width: 100%;
        text-align: center;
    }
    
    .bottom-bar {
        flex-direction: column;
        padding: var(--spacing-md);
    }
    
    .graph-container {
        height: 400px;
    }
}

/* Loading Animation */
@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.loading {
    animation: pulse 2s infinite;
}

/* Smooth transitions for all interactive elements */
* {
    transition: color 0.3s ease, background-color 0.3s ease, border-color 0.3s ease, transform 0.3s ease, box-shadow 0.3s ease;
}

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

::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb {
    background: rgba(102, 126, 234, 0.3);
    border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
    background: rgba(102, 126, 234, 0.5);
}