https://en.wikipedia.org/wiki/Cascading_Style_Sheets

Primary CSS unit

1. Font sizing with rem (root em) http://snook.ca/archives/html_[...]s/font-size-with-rem
2. https://mindtheshift.wordpress[...]css-reference-pixel/

Colors

1. https://developer.mozilla.org/de/docs/Web/CSS/Farben

Use of pseudo classes

Examples

.article aside li:first-child {
    border-top: 0 none;
    margin-top: 0;
    padding-top: 0;
}
.article aside li {
    border-top: 1px solid #eee;
    line-height: 16px;
    margin-top: 0;
    padding: 6px 0 6px 80px;
    position: relative;
}	

force line break

overflow-wrap: break-word;	

 table {
    table-layout: fixed;
    width: 100%;
}

table td {
    overflow-wrap: break-word;
}