Default css code for the badge (or highlight text) here

.tm-price-table_featured-inner {
    text-align: center;
    left: 0;
    width: 200%;
    -webkit-transform: translateY(-50%) translateX(-50%) translateX(35px) rotate(-45deg);
    -ms-transform: translateY(-50%) translateX(-50%) translateX(35px) rotate(-45deg);
    transform: translateY(-50%) translateX(-50%) translateX(35px) rotate(-45deg);
    margin-top: 35px;
    font-size: 14px;
    line-height: 2;
    color: #fff;
}

You can modify the custom css code into theme_name/custom/scss/custom.scss file.