Bootstrap 3 default styles for Gravity Forms (based on http://roots.io/style-gravity-forms-with-bootstrap/ and improved slightly)

bs3-gravity-forms.less

/*
 *
 * Bootstrap 3 reset for Gravity Forms
 *
 */

.gform_wrapper {
	ul {
		&:extend(.list-unstyled all);
		margin: 0;
	}
	li {
		&:extend(.form-group all);
		margin: 0;
	}
	form {
		margin-bottom: 0;
	}
	.gfield_required {
		padding-left: 1px;
		color: @state-danger-text;
	}
	.gfield_error {
		.gfield_label {
			color: @state-danger-text;
		}
		input, select, textarea {
			border-color: @alert-danger-border;
			background-color: @alert-danger-bg;
			color: @alert-danger-text;
			.form-control-focus(@alert-danger-text);
		}
	}
}
.ginput_container {
	input, select, textarea {
		&:extend(.form-control all);
	}
	textarea {
		height: auto;
	}
}
.gform_button {
	&:extend(.btn all, .btn-default all);
}
.validation_error {
	&:extend(.alert all, .alert-danger all);
}
#gforms_confirmation_message {
	&:extend(.alert all, .alert-success all);
}