.custom-control.overflow-checkbox .overflow-control-input {
    display: none;
}

    .custom-control.overflow-checkbox .overflow-control-input:checked ~ .overflow-control-indicator::after {
        -webkit-transform: rotateZ(45deg) scale(1);
        -ms-transform: rotate(45deg) scale(1);
        transform: rotateZ(45deg) scale(1);
        top: -6px;
        left: 5px;
    }

    .custom-control.overflow-checkbox .overflow-control-input:checked ~ .overflow-control-indicator::before {
        opacity: 1;
    }

    .custom-control.overflow-checkbox .overflow-control-input:disabled ~ .overflow-control-indicator {
        opacity: .5;
        border: 2px solid #ccc;
    }

        .custom-control.overflow-checkbox .overflow-control-input:disabled ~ .overflow-control-indicator:after {
            border-bottom: 4px solid #ccc;
            border-right: 4px solid #ccc;
        }

.custom-control.overflow-checkbox .overflow-control-indicator {
    border-radius: 3px;
    display: inline-block;
    position: absolute;
    top: 4px;
    left: 0;
    width: 16px;
    height: 16px;
    border: 2px solid #00909e;
}

    .custom-control.overflow-checkbox .overflow-control-indicator::after {
        content: '';
        display: block;
        position: absolute;
        width: 16px;
        height: 16px;
        -webkit-transition: .3s;
        -o-transition: .3s;
        transition: .3s;
        -webkit-transform: rotateZ(90deg) scale(0);
        -ms-transform: rotate(90deg) scale(0);
        transform: rotateZ(90deg) scale(0);
        width: 10px;
        border-bottom: 4px solid #00909e;
        border-right: 4px solid #00909e;
        border-radius: 3px;
        top: -2px;
        left: 2px;
    }

    .custom-control.overflow-checkbox .overflow-control-indicator::before {
        content: '';
        display: block;
        position: absolute;
        width: 16px;
        height: 16px;
        -webkit-transition: .3s;
        -o-transition: .3s;
        transition: .3s;
        width: 10px;
        border-right: 7px solid #fff;
        border-radius: 3px;
        -webkit-transform: rotateZ(45deg) scale(1);
        -ms-transform: rotate(45deg) scale(1);
        transform: rotateZ(45deg) scale(1);
        top: -4px;
        left: 5px;
        opacity: 0;
    }