.remove_nested_fields {
    @extend .btn;
    @extend .btn-danger;
    @extend .btn-link;

    color: $btn-danger-color;

    &:hover, &:active, &:visited, &:focus {
        color: $btn-danger-color;
    }
}

.add_nested_fields_container {
    @extend .text-center;
}

.form-horizontal .add_nested_fields {
    @extend .col-sm-offset-3;
    @extend .btn;
    @extend .btn-primary;
    @extend .btn-link;
    @extend .btn-sm;

    color: $btn-primary-color;

    &:hover, &:active, &:visited, &:focus {
        color: $btn-primary-color;
    }
}
.remove_nested_fields {
    @extend .btn;
    @extend .btn-danger;

    color: $btn-primary-color;

    &:hover, &:active, &:visited, &:focus {
        color: $btn-primary-color;
    }
}

.add_nested_fields_container {
    @extend .text-center;
}

.form-horizontal .add_nested_fields {
    @extend .col-sm-offset-3;
    @extend .btn;
    @extend .btn-primary;
    @extend .btn-sm;
}
Tweak close button styling for nested fields
Tweak close button styling for nested fields

Get rid of the btn-link class because it does bad things with the text
color in the button
