<div class="header">
        <img src="\static\client\img\change_theme.svg" class="change_theme" alt="change_theme">
        <h1>LearnFS</h1>
    </div>

.change_theme
{
    width: 19.1%;
    min-width: 30px;
    margin: 11px 8px;
    cursor: pointer;
    float: left;
    transition: transform 0.25s;
}

.change_theme:hover
{
     transform: scale(1.1);
}