.uk-radio:checked {
background-color: #e5e5e7;
border-color: #000000;
}
.uk-radio:checked {
background-image: url(https://ampel.campring.de/j5/images/haken.svg);
}

.uk-checkbox, .uk-radio {
display: inline-block;
height: 16px;
width: 16px;
overflow: hidden;
margin-top: -4px;
vertical-align: middle;
-webkit-appearance: none;
-moz-appearance: none;
background-color: transparent;
background-repeat: no-repeat;
background-position: 50% 50%;
transition: .2s ease-in-out;
transition-property: background-color, border-color, box-shadow;
border: 1px solid #212529;
}