style.css

/* */

* {
    box-sizing: border-box;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
}

html {
    font-family: 'IBM Plex Serif', serif;
    font-size: 18px;
}

body {
    border: 0px;
    margin: 0px;
    padding: 0px;
    color: black;
    background-color: #fcfffc;
}

.main {
    margin: 4em 0px 8em 0px;
    padding: 0.4em 0.2em;

    column-count: 3;
    column-width: 22em;

    -webkit-column-gap: 0px;
    -moz-column-gap: 0px;
    column-gap: 0px;
    
    column-rule: 1px solid lightgrey;
}

.main > div {
    -webkit-column-break-inside: avoid;
    -moz-column-break-inside: avoid;
    -o-column-break-inside: avoid;
    -ms-column-break-inside: avoid;
    column-break-inside: avoid;
    page-break-inside: avoid;

    /* zo moet het */
    break-inside: avoid;

    padding: 0px 1em;
    margin: 0px 0.2em 4em 0.2em;
}

.footer {
    text-align: center;
    font-size: small;
}

h1 {
    margin-top: 4em;
    text-align: center;
}

h1, h2 {
    font-variant: small-caps;
    color: #62757f;
    letter-spacing: .1em;
    margin-top: 2em;
}
h1 {
    font-size: xx-large;
    font-weight: 200;
}
h2 {
    margin-top: 0px;
    font-size: x-large;
    font-weight: 300;
}

ul {
    list-style-type: square;
}
ul>li>ul {
    list-style-type: circle;
}
ul>li>ul>li>ul {
    list-style-type: disc;
}

ul {
    margin-top: .4em;
    margin-bottom: .8em;
}

li {
    margin-bottom: .5em;
}

a {
    text-decoration: none;
    color: #0000ee;
}

a:hover {
    text-decoration: underline;
}