livewire-material/resources/css/components/menu.css

/*
 * The menus: the exposed dropdown a field drops open, and what `<x-menu>` cannot say in utilities.
 *
 * Two lists wear the dropdown, so a form reads as one family:
 *
 *   - `<x-select>`'s: the native <select>, opted into the browser's customizable select
 *     (`appearance: base-select`). `::picker(select)` is the menu and each <option> a row, while the
 *     keyboard, type-to-find, the screen reader and the form value stay the browser's own.
 *   - `<x-choices searchable>`'s listbox, which Alpine draws, as `.field-menu` and `.field-option`.
 *
 * M3's menu as its tokens have it: surface-container at elevation 2, extra-small corner, 48px rows in
 * body-large, the chosen row in secondary-container with a tick at its end (so it is not told by colour
 * alone), and the state layer on hover (only where a pointer can hover) and focus.
 *
 * Unlayered, as the rest of the package's component CSS, so a utility on the call site cannot half-undo
 * a row.
 *
 * Where the browser has no customizable select, the select keeps its native list, which
 * `color-scheme` themes. Every rule for the select's own rows is inside `@supports`: a browser that
 * paints option colours into its native list would otherwise show a half-painted one.
 */

/*
 * `<x-menu>` and the submenus inside it.
 *
 * A submenu is a popover of its own nested in the menu's, so it cannot take the container colour
 * from a class the item knows nothing about: the menu declares the pair as custom properties,
 * which a nested popover inherits down the DOM whatever the top layer does with its painting. The
 * fallbacks are the standard menu's, for a submenu in some other list (a FAB menu's).
 */
[data-menu] {
    --material-menu-surface: var(--md-sys-color-surface-container-low);
    --material-menu-ink: var(--md-sys-color-on-surface);
}

[data-menu][data-vibrant] {
    --material-menu-surface: var(--md-sys-color-tertiary-container);
    --material-menu-ink: var(--md-sys-color-on-tertiary-container);
}

[data-submenu] {
    background: var(--material-menu-surface, var(--md-sys-color-surface-container-low));
    color: var(--material-menu-ink, var(--md-sys-color-on-surface));
}

.field-menu {
    max-block-size: 18rem;
    overflow-y: auto;
    padding-block: 0.5rem;
    border-radius: var(--md-sys-shape-corner-xs);
    background: var(--md-sys-color-surface-container);
    box-shadow: var(--md-sys-elevation-2);
}

/* As a popover (`<x-choices searchable>`), it hangs under its field, as wide, and goes above only
   when there is no room below. */
.field-menu[popover] {
    inset: auto;
    top: anchor(bottom);
    left: anchor(left);
    width: anchor-size(width);
    margin: 0.25rem 0;
    border: 0;
    padding-inline: 0;
    color: var(--md-sys-color-on-surface);
    position-try-fallbacks: flip-block;
}

.field-option[aria-disabled="true"] {
    color: color-mix(in srgb, var(--md-sys-color-on-surface) 38%, transparent);
    cursor: default;
}

.field-option {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    min-block-size: 3rem;
    padding-inline: 1rem;
    color: var(--md-sys-color-on-surface);
    font: var(--md-sys-typescale-body-lg);
    letter-spacing: var(--md-sys-typescale-body-lg-tracking);
    cursor: pointer;
}

/* `data-active` is the row the arrow keys or the pointer are on. */
.field-option[data-active] {
    background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent);
}

.field-option[aria-selected="true"] {
    background: var(--md-sys-color-secondary-container);
    color: var(--md-sys-color-on-secondary-container);
}

.field-option[aria-selected="true"][data-active] {
    background: color-mix(in srgb, var(--md-sys-color-on-secondary-container) 8%, var(--md-sys-color-secondary-container));
}

.field-check {
    margin-inline-start: auto;
}

.field-option:not([aria-selected="true"]) .field-check {
    visibility: hidden;
}

@supports (appearance: base-select) {
    select.field-control,
    select.field-control::picker(select) {
        appearance: base-select;
    }

    /* The menu. The browser anchors it to the select; the select covers its whole
       field (field.css), so the menu is at least the field's width. It hangs under
       the field and goes above only when it does not fit there — the browser's own
       order tries the roomier side first, which opened a menu upwards with room to
       spare under it. It opens with a fade and a grow on the spatial spring and
       closes with a fade, as `<x-menu>` does. */
    select.field-control::picker(select) {
        position-try-order: normal;
        max-block-size: 18rem;
        max-inline-size: calc(100vw - 2rem);
        margin-block: 0.25rem;
        padding-block: 0.5rem;
        border: 0;
        border-radius: var(--md-sys-shape-corner-xs);
        background: var(--md-sys-color-surface-container);
        color: var(--md-sys-color-on-surface);
        box-shadow: var(--md-sys-elevation-2);
        opacity: 0;
        transform-origin: top;
        transition-property: opacity, display, overlay;
        transition-duration: var(--md-sys-motion-effects-fast-duration);
        transition-timing-function: var(--md-sys-motion-effects-fast);
        transition-behavior: allow-discrete;
    }

    select.field-control:open::picker(select) {
        opacity: 1;
        transition-property: opacity, scale, display, overlay;
        transition-duration: var(--md-sys-motion-spatial-fast-duration);
        transition-timing-function: var(--md-sys-motion-spatial-fast);
    }

    @starting-style {
        select.field-control:open::picker(select) {
            opacity: 0;
            scale: 0.95;
        }
    }

    select.field-control option {
        display: flex;
        align-items: center;
        gap: 0.75rem;
        min-block-size: 3rem;
        padding-block: 0;
        padding-inline: 1rem;
        background: transparent;
        color: var(--md-sys-color-on-surface);
        font: var(--md-sys-typescale-body-lg);
        letter-spacing: var(--md-sys-typescale-body-lg-tracking);
        outline: none;
        cursor: pointer;
    }

    @media (hover: hover) {
        select.field-control option:hover {
            background: color-mix(in srgb, var(--md-sys-color-on-surface) 8%, transparent);
        }
    }

    select.field-control option:focus-visible {
        background: color-mix(in srgb, var(--md-sys-color-on-surface) 10%, transparent);
    }

    select.field-control option:checked {
        background: var(--md-sys-color-secondary-container);
        color: var(--md-sys-color-on-secondary-container);
    }

    @media (hover: hover) {
        select.field-control option:checked:hover {
            background: color-mix(in srgb, var(--md-sys-color-on-secondary-container) 8%, var(--md-sys-color-secondary-container));
        }
    }

    select.field-control option:checked:focus-visible {
        background: color-mix(in srgb, var(--md-sys-color-on-secondary-container) 10%, var(--md-sys-color-secondary-container));
    }

    select.field-control option:disabled {
        background: transparent;
        color: color-mix(in srgb, var(--md-sys-color-on-surface) 38%, transparent);
        cursor: default;
    }

    /* The tick, at the row's end: the browser draws it before the label, and hides
       it on every row but the chosen one. The Material Symbol, as a mask, so it
       takes the row's ink. */
    select.field-control option::checkmark {
        content: "";
        order: 1;
        flex: none;
        inline-size: 1.5rem;
        block-size: 1.5rem;
        margin-inline-start: auto;
        background-color: currentColor;
        mask: url("../../svg/symbols/outlined/check.svg") center / contain no-repeat;
    }
}