chromium/ash/webui/common/resources/cr_elements/cr_action_menu/cr_action_menu.html

<style>
  :host {
    --cr-menu-background-color: var(--cros-sys-base_elevated);
    --cr-menu-background-focus-color: var(--cros-sys-hover_on_subtle);
  }

  :host dialog {
    background-color: var(--cr-menu-background-color);
    border: none;
    border-radius: var(--cr-menu-border-radius, 4px);
    box-shadow: var(--cr-menu-shadow);
    margin: 0;
    min-width: 128px;
    outline: none;
    padding: 0;
    position: absolute;
  }

  @media (forced-colors: active) {
    :host dialog {
      /* Use border instead of box-shadow (which does not work) in Windows
         HCM. */
      border: var(--cr-border-hcm);
    }
  }

  :host-context([chrome-refresh-2023]) {
    --cr-hairline: 1px solid var(--color-menu-separator,
        var(--cr-fallback-color-divider));
    --cr-action-menu-disabled-item-color:
        var(--color-menu-item-foreground-disabled,
            var(--cr-fallback-color-disabled-foreground));
    --cr-action-menu-disabled-item-opacity: 1;
    --cr-menu-background-color: var(--color-menu-background,
        var(--cr-fallback-color-surface));
    --cr-menu-background-focus-color: var(--cr-hover-background-color);
    --cr-menu-shadow: var(--cr-elevation-2);
    --cr-primary-text-color: var(--color-menu-item-foreground,
        var(--cr-fallback-color-on-surface));
  }

  :host dialog::backdrop {
    background-color: transparent;
  }

  :host ::slotted(.dropdown-item) {
    -webkit-tap-highlight-color: transparent;
    background: none;
    border: none;
    border-radius: 0;
    box-sizing: border-box;
    color: var(--cr-primary-text-color);
    font: inherit;
    min-height: 32px;
    padding: 8px 24px;
    text-align: start;
    user-select: none;
    width: 100%;
  }

  :host ::slotted(.dropdown-item:not([hidden])) {
    align-items: center;
    display: flex;
  }

  :host ::slotted(.dropdown-item[disabled]) {
    color: var(--cr-action-menu-disabled-item-color,
        var(--cr-primary-text-color));
    opacity: var(--cr-action-menu-disabled-item-opacity, 0.65);
  }

  :host ::slotted(.dropdown-item:not([disabled])) {
    cursor: pointer;
  }

  :host ::slotted(.dropdown-item:focus) {
    background-color: var(--cr-menu-background-focus-color);
    outline: none;
  }

  @media (forced-colors: active) {
    :host ::slotted(.dropdown-item:focus) {
      /* Use outline instead of background-color (which does not work) in
         Windows HCM. */
      outline: var(--cr-focus-outline-hcm);
    }
  }

  .item-wrapper {
    background: var(--cr-menu-background-sheen);
    outline: none;
    padding: 8px 0;
  }

  :host-context([chrome-refresh-2023]) .item-wrapper {
    background: none;
  }
</style>
<dialog id="dialog" part="dialog" on-close="onNativeDialogClose_"
    role="application" aria-roledescription$="[[roleDescription]]">
  <div id="wrapper" class="item-wrapper" role="menu" tabindex="-1"
      aria-label$="[[accessibilityLabel]]">
    <slot id="contentNode" on-slotchange="onSlotchange_"></slot>
  </div>
</dialog>