.checkbox-container {
    display: block;
    position: relative;
    padding-left: 30px;
    margin-bottom: 0px;
    cursor: pointer;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
    color: #1b6ec2;
    font-weight: bold;
}

    /* Hide the browser's default checkbox */
    .checkbox-container input {
        position: absolute;
        opacity: 0;
        cursor: pointer;
        height: 0;
        width: 0;
    }

    /* Create a custom checkbox */
    .checkmark {
        position: absolute;
        top: 0;
        left: 0;
        height: 22px;
        width: 22px;
        background-color: white;       /*Licht-grijs*/
        border: 1px solid black;
    }

/* On mouse-over, add a grey background color */
.checkbox-container:hover input:enabled ~ .checkmark {
    background-color: #ccc; /*Donker grijs*/
}

/* When the checkbox is checked, add a blue background */
.checkbox-container input:checked ~ .checkmark {
    background-color: #1b6ec2;   /*#991f00*/
}

.checkbox-container input:not(:enabled):not(:checked) ~ .checkmark {
    background-color: lightgrey; 
}

.checkbox-container-blue input:checked ~ .checkmark {
    background-color: #2196F3;
}

/* Create the checkmark/indicator (hidden when not checked) */
.checkmark:after {
    content: "";
    position: absolute;
    display: none;
}

/* Show the checkmark when checked */
.checkbox-container input:checked ~ .checkmark:after {
    display: block;
}

/* Style the checkmark/indicator */
.checkbox-container .checkmark:after {
    left: 8px;
    top: 4px;
    width: 6px;
    height: 12px;
    border: solid white;
    border-width: 0 3px 3px 0;
    -webkit-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    transform: rotate(45deg);
}