site/_src/_assets/styles/bigchain/_dropdowns.scss

// The dropdown wrapper (`<div>`)
.dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-toggle {
    box-shadow: none;
    cursor: default;

    &:hover,
    &:focus {
        background: transparent;
    }

    &:after {
        content: '';
        display: inline-block;
        width: 14px;
        height: 10px;
        background: url('../img/icon-caret.svg') no-repeat center center;
        background-size: contain;
        transition: .15s ease-out;
    }

    .dropdown.show &,
    .dropdown--hover:hover & {
        &:after {
            transform: rotate(180deg);
        }
    }
}

// The dropdown menu
.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    z-index: 10;
    display: block;
    float: left;
    min-width: 10rem;
    padding: $spacer / 4 0;
    margin: 0;
    font-size: $font-size-base;
    color: $body-bg;
    text-align: left;
    list-style: none;
    border-radius: $border-radius;
    box-shadow: 0 3px 10px rgba(0, 0, 0, .3);
    background: $gray-dark;
    background-clip: padding-box;
    border: 0;
    max-height: 20rem;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    transition: .2s $timing-bounce;
    opacity: 0;
    transform: scale(1, 0);
    transform-origin: top;

    @media (max-width: 27rem), (max-height: 27rem) {
        max-height: 11.25rem;
    }
}

// Links, buttons, and more within the dropdown menu
.dropdown-item {
    display: block;
    width: 100%;
    padding: $spacer / 2 $spacer;
    clear: both;
    font-weight: $font-weight-normal;
    color: $brand-main-gray-light;
    text-align: inherit;
    white-space: nowrap;
    background-color: transparent;
    border: 0;
    box-shadow: none;

    &:hover,
    &:focus {
        text-decoration: none;
    }

    &.active {
        background: $brand-main-gray-light;
        color: $gray-dark;
        text-decoration: none;
    }

    &[rel='external']:after {
        margin-left: 0;
    }
}

.dropdown-menu.show,
.dropdown--hover:hover > .dropdown-menu {
    transform: scale(1, 1);
    opacity: 1;
}

.dropdown--hover > .dropdown-toggle:active {
    // Without this, clicking will make it sticky
    pointer-events: none;
}