body {

    background: linear-gradient(to bottom, #edecd8 15%, #ccffcc 100%) no-repeat center center fixed;
    background-size: cover;
}
a {
    font-family: Calibri;
    font-size: 30px;
    text-decoration: none;
    font-weight: 900;
}
.podtrzeni {
    display: inline;
    position: relative;
    overflow: hidden;
}

    .podtrzeni:after {
        content: "";
        position: absolute;
        z-index: -1;
        right: 0;
        width: 0;
        bottom: -3px;
        background: #4cff00;
        height: 4px;
        transition-property: width;
        transition-duration: 0.5s;
        transition-timing-function: ease-out;
    }

    .podtrzeni:hover:after,
    .podtrzeni:focus:after,
    .podtrzeni:active:after {
        left: 0;
        right: auto;
        width: 100%;
    }