hakyll-blog/css/syntax.css

code {
    font-size: 13px;
    background-color: rgb(250,250,250);
    border: 1px solid rgb(200,200,200);
    padding: 2px 4px;
}

pre code {
    display: block;
    padding: 5px 10px;
    margin-bottom: 1em;
    overflow-x:auto;
}