h1 .anchor,
h2 .anchor,
h3 .anchor,
h4 .anchor {
    display: inline-block;
    position: relative;
    width: 0;
    margin: 0;
    left: 1em;
    color: #03a9f4;
    opacity: 0;
    font-size: 0.75em;
    text-decoration: none;
    transition: opacity 0.25s ease, color 0.25s ease
}

h1:hover .anchor,
h1 .anchor:focus,
h2:hover .anchor,
h2 .anchor:focus,
h3:hover .anchor,
h3 .anchor:focus,
h4:hover .anchor,
h4 .anchor:focus {
    opacity: 1
}

[data-glow="true"] {
    animation: highlight_glow 2s
}

@keyframes highlight_glow {
    0% {
        background: none
    }
    10% {
        background: #153f82
    }
    100% {
        background: none
    }
}