// Ẩn shadow bằng cách ghi đè
.btn:active,
.btn:focus,
.form-control:active,
.form-control:focus {
    outline: 0 none;
    box-shadow: none;
}

.form-control:focus,
.form-control:active,
.btn:focus,
.btn:active,
.custom-select:focus,
.custom-select:active,
.custom-control-input:focus ~ .custom-control-label::before,
.custom-control-input:active ~ .custom-control-label::before {
    outline: 0 none;
    box-shadow: none;
}