In your themes settings section (admin/appearance/customize) or you can add style customization's, edited via this url  ---> /...arance/customize/css.

Here's a custom example to get you started! Just delete them from the edit box after testing, you'll get the idea!

h1{
    font-size: 1.7rem;
    line-height: 1.6rem;
    padding-left: 0px;
    color: #6B8088;/** OW_Control type: color, key: titleColor, label: - Title, section: 2. Colors **/
    text-transform: uppercase;
    margin-left: 0px;
    background-repeat: no-repeat;
    font-family: "Trebuchet MS", "Helvetica CY", sans-serif;
    margin-top: 15px;
    /* text-align: center; */
    /* background: url(images/divider_line.png); */
    border-bottom: 5px solid rgba(121, 121, 121, 0.1);
    background-repeat: repeat-x;
    background-position: bottom left;
    padding-bottom: 10px;
}