.ql-keyscale-card {
    display: block;
    position: relative;
    margin: 1.5rem auto;
    padding: 0; 
    /* Theme-aware borders and backgrounds */
    border: 1px solid var(--sandbox-card-border, var(--bs-border-color));
    border-radius: 8px;
    background-color: var(--sandbox-card-bg, var(--bs-body-bg));
    box-shadow: 0 4px 12px rgba(var(--bs-black-rgb), 0.15);
    
    width: 100%; 
    max-width: 800px;
    /* Height is now a suggestion; the controller should manage the aspect ratio */
    min-height: 400px;
    text-align: center;
    overflow: hidden; 
}

/* Focus state when the blot is selected in Quill */
.ql-keyscale-card.ql-selected {
    outline: 2px solid var(--sandbox-accent, var(--bs-primary));
    box-shadow: 0 0 10px rgba(var(--bs-primary-rgb), 0.4);
}