wagtail/client/scss/components/_skiplink.scss

.skiplink {
    display: block;
    position: fixed;
    top: -1000rem;
    left: 1rem;
    z-index: 30;

    &:focus {
        top: 1rem;
    }

    &.button {
        background: $color-green-darker;
        border: $color-green-darker;
    }
}