css

.border-box {
    box-sizing: border-box;
}

.ba {
    border-style: solid;
    border-width: 1px;
}

.b--black-20 {
    border-color: rgba(0, 0, 0, .2);
}

.br2 {
    border-radius: .25rem;
}

.db {
    display: block;
}

.normal {
    font-weight: normal;
}

.b {
    font-weight: bold;
}

.link {
    text-decoration: none;
    transition: color .15s ease-in;
}

.link:link, .link:visited {
    transition: color .15s ease-in;
}

.link:hover {
    transition: color .15s ease-in;
}

.link:active {
    transition: color .15s ease-in;
}

.link:focus {
    transition: color .15s ease-in;
    outline: 1px dotted currentColor;
}

.w-100 {
    width: 100%;
}

.black-80 {
    color: rgba(0, 0, 0, .8);
}

.black-60 {
    color: rgba(0, 0, 0, .6);
}

.hover-black:hover {
    color: #000;
}

.hover-black:focus {
    color: #000;
}

.hover-blue:hover {
    color: #357edd;
}

.hover-blue:focus {
    color: #357edd;
}

.pa2 {
    padding: .5rem;
}

.pa4 {
    padding: 2rem;
}

.mb2 {
    margin-bottom: .5rem;
}

.underline {
    text-decoration: underline;
}

.f6 {
    font-size: .875rem;
}

.measure {
    max-width: 30em;
}