.assignments-day-preview-backdrop {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: var(--z-popover);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease;
}

.assignments-day-preview-backdrop.is-open {
    opacity: 1;
    pointer-events: auto;
}

.assignments-day-preview {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%) scale(0.95);
    width: 90%;
    max-width: 400px;
    max-height: 80vh;
    display: flex;
    flex-direction: column;
    background: var(--color-card-bg);
    border-radius: var(--radius-lg);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    z-index: var(--z-overlay-top);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease, transform 0.2s ease;
    overflow: hidden;
}

.assignments-day-preview.is-open {
    opacity: 1;
    pointer-events: auto;
    transform: translate(-50%, -50%) scale(1);
}

.assignments-day-preview__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-smd) var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
    flex-shrink: 0;
}

.assignments-day-preview__label {
    font-weight: 700;
    font-size: var(--font-size-lg);
    color: var(--color-text);
}

.assignments-day-preview__close {
    background: none;
    border: none;
    font-size: 1.35rem;
    line-height: 1;
    color: var(--color-text-light);
    cursor: pointer;
    padding: var(--spacing-2xs) var(--spacing-xs);
    border-radius: var(--radius-sm);
}

.assignments-day-preview__close:hover {
    color: var(--color-text);
    background: var(--color-surface-hover);
}

.assignments-day-preview__timeline {
    overflow-y: auto;
    overscroll-behavior: contain;
    padding: var(--spacing-xs) 0;
    flex: 1;
}

.assignments-day-preview__row {
    display: flex;
    align-items: stretch;
    min-height: 2.25rem;
}

.assignments-day-preview__hour {
    flex-shrink: 0;
    width: 3.25rem;
    padding: var(--spacing-xsm) var(--spacing-sm) var(--spacing-xsm) var(--spacing-smd);
    font-size: var(--font-size-2xs);
    font-weight: var(--font-weight-medium);
    color: var(--color-text-light);
    text-align: right;
    line-height: 1;
    white-space: nowrap;
}

.assignments-day-preview__slot {
    flex: 1;
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-2xs) var(--spacing-sm) var(--spacing-2xs) var(--spacing-sm);
    min-height: 2.25rem;
}

.assignments-day-preview__row:last-child .assignments-day-preview__slot {
    border-bottom: 1px solid var(--color-border);
}

.assignments-day-preview__event {
    display: flex;
    align-items: center;
    gap: var(--spacing-xsm);
    padding: var(--spacing-xs) var(--spacing-sm);
    margin: var(--spacing-2xs) 0;
    border-radius: var(--radius-md);
    background: #f3f4f6;
    font-size: var(--font-size-xs);
    line-height: 1.3;
    border-left: 3px solid var(--color-text-muted);
}

.assignments-day-preview__event--target {
    background: color-mix(in srgb, var(--color-action) 10%, transparent);
    border-left-color: var(--color-action);
}

.assignments-day-preview__event-time {
    flex-shrink: 0;
    font-weight: var(--font-weight-medium);
    color: var(--color-text);
    font-size: var(--font-size-xs);
}

.assignments-day-preview__event--target .assignments-day-preview__event-time {
    color: var(--color-action);
}

.assignments-day-preview__event-label {
    flex: 1;
    min-width: 0;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    color: var(--color-text);
    font-weight: 500;
}

.assignments-day-preview__event--target .assignments-day-preview__event-label {
    color: var(--color-text);
    font-weight: var(--font-weight-medium);
}

@media (max-width: 480px) {
    .assignments-day-preview {
        width: 95%;
        max-height: 85vh;
    }
}

/* ── Phone (<768px) ─────────────────────────────────────────────────────────
   The centred card becomes a full sheet under the header: no translate, so
   the open transition is opacity only. Stays LAST in the file. */
@media (max-width: 767.98px) {
    .assignments-day-preview {
        inset: var(--header-bottom) 0 0 0;
        width: auto;
        max-height: none;
        transform: none;
        border-radius: var(--radius-none);
    }

    .assignments-day-preview.is-open {
        transform: none;
    }

    .assignments-day-preview__close {
        min-width: var(--control-h-touch);
        min-height: var(--control-h-touch);
    }
}