:root {
    /* Dark theme (default) */
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #3d3d3d;
    --text-primary: #ffffff;
    --text-secondary: #cccccc;
    --accent-primary: #4a9eff;
    --accent-success: #28a745;
    --accent-warning: #ffc107;
    --accent-danger: #dc3545;
    --accent-info: #17a2b8;
    --border-color: #555555;
    --tape-bg: #2d2d2d;
    --tape-cell-bg: #3d3d3d;
    --tape-head-bg: #ff6b6b;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

[data-theme="light"] {
    --bg-primary: #f8f9fa;
    --bg-secondary: #ffffff;
    --bg-tertiary: #e9ecef;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --accent-primary: #007bff;
    --accent-success: #28a745;
    --accent-warning: #ffc107;
    --accent-danger: #dc3545;
    --accent-info: #17a2b8;
    --border-color: #dee2e6;
    --tape-bg: #ffffff;
    --tape-cell-bg: #f8f9fa;
    --tape-head-bg: #dc3545;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: all 0.3s ease;
}

#app {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
header {
    margin-bottom: 30px;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 20px;
}

.header-text {
    flex: 1;
}

header h1 {
    color: var(--accent-primary);
    margin-bottom: 5px;
    font-size: 2rem;
    font-weight: 700;
}

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

/* Theme Switch */
.theme-switch {
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    padding: 10px;
    border-radius: 25px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
}

.theme-switch:hover {
    background: var(--bg-tertiary);
}

.theme-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* Switch Slider */
.slider {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 24px;
    background-color: #ccc;
    border-radius: 24px;
    transition: all 0.3s ease;
}

.slider:before {
    content: "";
    position: absolute;
    height: 20px;
    width: 20px;
    left: 2px;
    bottom: 2px;
    background-color: white;
    border-radius: 50%;
    transition: all 0.3s ease;
}

#theme-toggle {
    display: none;
}

#theme-toggle:checked + .slider {
    background-color: var(--accent-primary);
}

#theme-toggle:checked + .slider:before {
    transform: translateX(26px);
}

/* Sections */
section {
    background: var(--bg-secondary);
    padding: 20px;
    margin-bottom: 20px;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow);
}

section h2 {
    color: var(--accent-primary);
    margin-bottom: 15px;
    font-size: 1.3rem;
    font-weight: 600;
    border-bottom: 2px solid var(--accent-primary);
    padding-bottom: 8px;
}

/* Compact Panel */
.compact-panel {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

section.compact {
    margin-bottom: 0;
}

/* Configuration */
.config-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 15px;
    margin-bottom: 15px;
}

.config-group {
    display: flex;
    flex-direction: column;
}

.config-group label {
    margin-bottom: 5px;
    font-weight: 500;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.config-group input,
.config-group select {
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 0.95rem;
    transition: border-color 0.3s ease;
}

.config-group input:focus,
.config-group select:focus {
    outline: none;
    border-color: var(--accent-primary);
}

/* Tape Visualization */
.tape-container {
    background: var(--tape-bg);
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 15px;
    overflow-x: auto;
}

.tape {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 2px;
    min-height: 80px;
    position: relative;
}

.tape-cell {
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--tape-cell-bg);
    border: 2px solid var(--border-color);
    border-radius: 6px;
    font-size: 1.2rem;
    font-weight: bold;
    position: relative;
    transition: all 0.3s ease;
}

.tape-cell.active {
    background: var(--tape-head-bg);
    color: white;
    border-color: var(--tape-head-bg);
    transform: scale(1.1);
    z-index: 2;
    box-shadow: 0 0 10px rgba(255, 107, 107, 0.5);
}

.tape-index {
    position: absolute;
    bottom: -25px;
    font-size: 0.75rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.tape-controls {
    display: flex;
    gap: 10px;
    justify-content: center;
}


.tape-editor {
    margin-bottom: 20px;
    padding: 15px;
    background: var(--bg-primary);
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.tape-editor label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text-secondary);
}

.tape-input-group {
    display: flex;
    gap: 10px;
    align-items: center;
}

#tape-input {
    flex: 1;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1rem;
}

#tape-input:focus {
    outline: none;
    border-color: var(--accent-primary);
}

#apply-tape {
    min-width: 120px;
}

/* Buttons */
button {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    transition: all 0.3s ease;
    min-width: 100px;
}

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

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

.btn-warning {
    background: var(--accent-warning);
    color: black;
}

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

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

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

button:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

/* Control Section Compact */
.control-section.compact .control-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    margin-bottom: 20px;
}

.control-section.compact .control-buttons button {
    min-width: auto;
    padding: 12px 8px;
    font-size: 0.9rem;
}

/* Simulation Info Compact */
.simulation-info.compact {
    background: var(--bg-primary);
    padding: 15px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.info-group h3 {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 8px;
    font-weight: 600;
}

.command-display {
    background: var(--bg-tertiary);
    padding: 10px;
    border-radius: 6px;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    color: var(--accent-primary);
    border: 1px solid var(--border-color);
    min-height: 20px;
}

.info-stats {
    display: grid;
    grid-template-columns: 1fr;
    gap: 8px;
    margin-top: 15px;
}

.stat-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 6px 0;
    border-bottom: 1px solid var(--border-color);
}

.stat-item:last-child {
    border-bottom: none;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.stat-value {
    font-weight: 600;
    color: var(--accent-primary);
}

.stat-value.ready {
    color: var(--accent-success);
}

.stat-value.running {
    color: var(--accent-warning);
}

.stat-value.completed {
    color: var(--accent-success);
}

/* Library Section Compact */
.library-section.compact .library-controls {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.library-section.compact select {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 0.9rem;
}

.library-section.compact button {
    width: 100%;
}

/* IO Section Compact */
.io-section.compact .io-controls {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.import-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

#import-file {
    display: none;
}

#import-trigger {
    width: 100%;
}

.file-name {
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-align: center;
    font-style: italic;
}

/* Transition Table */
.transitions-container {
    overflow-x: auto;
}

#transition-table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 15px;
    background: var(--bg-primary);
    border-radius: 6px;
    overflow: hidden;
}

#transition-table th,
#transition-table td {
    padding: 12px;
    text-align: left;
    border: 1px solid var(--border-color);
    font-size: 0.9rem;
}

#transition-table th {
    background: var(--bg-tertiary);
    font-weight: 600;
    color: var(--accent-primary);
}

#transition-table tr:nth-child(even) {
    background: var(--bg-secondary);
}

#transition-table select,
#transition-table input {
    width: 100%;
    padding: 6px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 0.85rem;
}

/* Animation for tape head */
@keyframes pulse {
    0% { transform: scale(1); box-shadow: 0 0 0 rgba(255, 107, 107, 0.4); }
    50% { transform: scale(1.05); box-shadow: 0 0 10px rgba(255, 107, 107, 0.8); }
    100% { transform: scale(1); box-shadow: 0 0 0 rgba(255, 107, 107, 0.4); }
}

.tape-cell.active {
    animation: pulse 0.6s ease-in-out;
}

/* Responsive Design */
@media (max-width: 968px) {
    .compact-panel {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    #app {
        padding: 10px;
    }
    
    .header-content {
        flex-direction: column;
        gap: 15px;
    }
    
    header h1 {
        font-size: 1.6rem;
    }
    
    .config-grid {
        grid-template-columns: 1fr;
    }
    
    .control-section.compact .control-buttons {
        grid-template-columns: 1fr;
    }
    
    .tape-cell {
        width: 50px;
        height: 50px;
        font-size: 1rem;
    }
    
    section {
        padding: 15px;
    }
}

@media (max-width: 480px) {
    .header-text h1 {
        font-size: 1.4rem;
    }
    
    .header-text p {
        font-size: 1rem;
    }
    
    .theme-switch {
        align-self: stretch;
        justify-content: center;
    }
    
    .tape-cell {
        width: 40px;
        height: 40px;
        font-size: 0.9rem;
    }
    
    button {
        min-width: 80px;
        padding: 8px 12px;
        font-size: 0.85rem;
    }
}