Here is one possible flex-based solution (SCSS):
dl {
display: flex;
flex-wrap: wrap;
width: 100%;
dt {
width: 150px;
}
dd {
margin: 0;
flex: 1 0 calc(100% - 150px);
}
}
that works for the following HTML (pug)
dl
dt item 1
dd desc 1
dt item 2
dd desc 2