header {
    background: #D0ECFA;
    padding-top: 0.25em;
    padding-bottom: 0.25em;
    margin-bottom: 0.5em;
    text-align: center;

}

ul {
    list-style: none;
}

ul a {
    color: rgb(46, 40, 39);
}

ul a:hover {
    text-decoration: none;
}

.clickable {
    cursor: pointer;
}

.header-title-text {
    margin-bottom: 1.5em;
    text-align: center;
    color: #019DE0;
}

.header-title-text>h1 {
    padding: 0;
    margin: 0;
    margin-top: 15px;
    font-size: 2.4em;
}

.header-title-text>h2 {
    padding: 0;
    margin: 0;
    margin-top: 10px;
    font-size: 2em;
}

.header-buttons {
    display: inline-block;
    margin-bottom: 1em;
}

.btn-header {
    background: hsl(31, 60%, 82%);
    font-size: 0.9em;
    width: 14em;
    outline: 0 !important;
}

.btn-header+.btn-header {
    margin-left: 1em;
}

.active-sport {
    background: hsl(31, 60%, 95%);
}

.center-div {
    text-align: center;
}

.navi {
    padding-left: 0;
    overflow: hidden;
    list-style: none;
    display: inline-block;
    margin-bottom: 1.4em;
}

.navi>li {
    float: left;
    font-size: 1.4em;
    padding-left: 0.5em;
    padding-right: 0.5em;
    padding-top: 0.2em;
    padding-bottom: 0.2em;
}

.navi>li+li {
    margin-left: 2em;
}

.navi>li>a {
    color: hsl(0, 0%, 50%);
}

.navi>li>a:visited {
    color: hsl(0, 0%, 50%);
}

.navi>li.active-nav-item {
    background: hsl(0, 0%, 98%);
}

.u1 {
    border: 0;
    max-width: 240px;
}

.videos {
    margin-bottom: 2.4em;
}

.videos>li>h3 {
    cursor: pointer;
}

.further-books,
.material {
    font-size: 1.4em;
    cursor: pointer;
}

.sub-headline {
    margin-top: 0;
    margin-bottom: 25px;
    overflow: hidden;
}

.close-video {
    float: right;
    margin-right: 18%;
}

#video-sections-tennis {
    list-style: none;
}

#video-sections-tennis>li {
    margin-bottom: 45px;
}

#video-tennis {
    list-style: none;
}

#video-tennis>li {
    margin-bottom: 25px;
}

#video-tennis>li:first-child {
    margin-top: 25px;
}

.download-link {
    display: block;
    float: right;
    margin-right: 18%;
}