<p style="text-align: center;">
    <a class="buttonL" href="http://cns.uni.lu/homel"><</a>
    <a class="buttonR" href="http://cns.uni.lu/homer">></a>
</p>

.buttonL {
    border-radius: 50%;
    position:fixed;
    top: 50%;
    left: 0%;
    background-color: transparent;
    border: none;
    color: grey;
    padding: 5px 20px;
    text-align: center;
    text-decoration: none !important;
    display: inline-block;
    font-size: 50px;
    margin: 4px 2px;
    cursor: pointer;
    font-weight: 900;
}

.buttonR {
    border-radius: 50%;
    position:fixed;
    top: 50%;
    right: 0%;
    background-color: transparent;
    border: none;
    color: grey;
    padding: 5px 20px;
    text-align: center;
    text-decoration: none !important;
    display: inline-block;
    font-size: 50px;
    margin: 4px 2px;
    cursor: pointer;
    font-weight: 900
}

text-decoration:none !important;

border-bottom: none;

box-shadow: none;