header {
    display: flex;
    display: -webkit-box;
    display: -moz-box;
    display: -webkit-flex;
    display: -ms-flexbox;

    justify-content: space-between;
    -webkit-box-pack: justify;
    -moz-box-pack: justify;
    -ms-flex-pack: justify;
}

header .language-select {
    position: absolute;
    top: 10px;
    right: 10px;
}
header .language-select ul {
    display: inline-block;
    list-style-type: none;
    margin: 0;
    padding: 0;
}
header .language-select ul li {
    display: inline-block;
}
header .language-select ul li:not(:last-child):after {
    content: ' / ';
}

header .language-select a:link,
header .language-select a:visited,
header .language-select a:active {
    text-decoration: none;
}

header .language-select a:hover {
    text-decoration: underline;
}

.error pre {
    white-space: pre-wrap;
    text-align: left;
}