ul.source_tag_pills {
    list-style-type: none;
}

ul.source_tag_pills li {
    display: inline-block;
    margin: 7px;
    padding: 2px 20px;
    font-weight: 600;
    color: black;
    border: 2px solid black;
    border-radius: 15px;
    transition: background 0.15s cubic-bezier(0.445, 0.05, 0.55, 0.95);
}

ul.source_tag_pills li:hover {
    background: #EFEFEF;
}