#structures {
    text-align: center;
    margin: 1rem auto;
    position: relative;
    max-width: 400px;
}

#twoD-viewer {
    min-height: 250px;
}

#rdkit-loader-text {
    color: #6c757d;
    font-size: 0.9rem;
}

#fg-checklist {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
    max-width: 480px;
    margin: 1rem auto 1.5rem;
    min-height: 130px;
}

@media (max-width: 500px) {
    #fg-checklist {
        grid-template-columns: repeat(2, 1fr);
    }
}

.fg-option {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 12px;
    border: 2px solid #dee2e6;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.95rem;
    transition: all 0.15s;
    user-select: none;
}

.fg-option:hover {
    border-color: #6153cc;
}

.fg-option.checked {
    background: #f0eeff;
    border-color: #6153cc;
    font-weight: 600;
}

.fg-option.correct {
    background: #d4edda;
    border-color: #28a745;
}

.fg-option.incorrect {
    background: #f8d7da;
    border-color: #dc3545;
}

.fg-option.missed {
    background: #fff3cd;
    border-color: #ffc107;
}

.fg-option input[type="checkbox"] {
    accent-color: #6153cc;
}

#fg-legend {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
    margin: 0.5rem auto 0;
    max-width: 480px;
}

.fg-legend-item {
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 0.82rem;
    color: #495057;
}

.fg-legend-swatch {
    display: inline-block;
    width: 14px;
    height: 14px;
    border-radius: 3px;
    border: 1px solid rgba(0,0,0,0.15);
}

#primary-controls {
    display: flex;
    justify-content: center;
    gap: 8px;
    align-items: center;
}