uc_unified-extensions.css

#unified-extensions-view {
  --uei-icon-size: 16px;

  .unified-extensions-item {
    margin-block: 0 !important;
    border-radius: var(--arrowpanel-menuitem-border-radius) !important;

    > .unified-extensions-item-action-button {
      .unified-extensions-item-message-deck {
        display: none;
      }

      &:hover {
        background-color: initial !important;
      }
    }

    > .unified-extensions-item-menu-button {
      list-style-image: url("chrome://global/skin/icons/more.svg") !important;
      padding: 0 !important;

      > .toolbarbutton-icon {
        padding: var(--arrowpanel-menuitem-padding-block) var(--arrowpanel-menuitem-padding-inline) !important;
        border: none !important;
        opacity: 0;
      }

      &:hover {
        color: var(--button-primary-bgcolor) !important;

        > .toolbarbutton-icon {
          background-color: initial !important;
        }

        &:active {
          color: var(--button-primary-hover-bgcolor) !important;
        }
      }
    }

    &:hover {
      background-color: var(--panel-item-hover-bgcolor);

      > .unified-extensions-item-menu-button > .toolbarbutton-icon {
        opacity: 1;
      }
    }

    &:has(> .unified-extensions-item-action-button:not([disabled]):hover:active) {
      background-color: var(--panel-item-active-bgcolor);
    }
  }
}