.your-button-class {
    border-bottom: 1px solid white;
    border-right: 1px solid white;

}

.your-button-class2 {
    border-top: 1px solid white;
    border-left: 1px solid white;
}


.your-button-class3 {
    border-bottom: 1px solid #C3C3C3;
    border-right: 1px solid #C3C3C3;
}

.your-button-class4 {
    border-top: 1px solid #C3C3C3;
    border-left: 1px solid #C3C3C3;
}