multipage form style list

Hi,
Im trying to style a list on a multipage form:
http://www.gestoriaonline-gestiona.es/formulario-contratacion-pack-autonomos-basico/

But I cant center text on header or change background color on header, or align header and other rows because they have no same width.

Any help?

Regards,

/* AÑADIDOS PARA GRAVITY FORMS */
body .gform_wrapper input[type=text],
body .gform_wrapper input[type=url],
body .gform_wrapper input[type=email],
body .gform_wrapper input[type=tel],
body .gform_wrapper input[type=number],
body .gform_wrapper input[type=password],
body .gform_wrapper select,
body .gform_wrapper textarea {
	border: 1px solid #AAAAAA!important;
	height: 14px;
	-moz-border-radius:9px;-webkit-border-radius:9px;border-radius:8px;
}
body .gform_wrapper .gfield_label {
	text-align: right;
/*	margin-left: 0px !important;*/
	width:300px !important;
}
body .gform_wrapper .gfield_html {
	margin-left: 0px !important;
}
body .gform_wrapper .gfield_description {
	margin-left: 0px !important;
}
body .gform_wrapper .gfield_checkbox {
	margin-left: 0px !important;
}
body .gform_wrapper .gform_body .gform_fields .gfield .ginput_listbody .gform_wrapper .gform_body .gform_fields .gfield .ginput_list {
	border: 1px solid red;
	margin-left: 0px !important;

}
body .gform_wrapper .gform_body .gform_fields #field_11_46.gfield_label {
	width: 300px !important;
	border: 1px solid red
	text-align: center !important;
}
body .gform_wrapper .gform_body .gform_fields #field_11_46.gfield input[type="text"] {
	margin: 0 10px 0 10px;
	width: 100px !important;
	-moz-border-radius:0px;-webkit-border-radius:0px;border-radius:0px !important;
}
/*body .gform_wrapper .gform_button {
	color: #000;
	border: 2px solid #ADD8E6!important;
	padding: 5px;
}*/
/*body .gform_wrapper input.button {
	font-size: 14px;
	border-top: 1px solid rgba(255, 255, 255, 0.25);
	color: #FFFFFF;
	background-color: #FF5C00;
	line-height: 1em;
	padding: 0.6em 1.3em;
	position: relative;
	text-align: center;
	text-decoration: none;
	text-shadow: 0 1px 1px rgba(0, 0, 0, 0.25);
	white-space: nowrap;
	display: inline-block;
	cursor: pointer;
}*/
/* END AÑADIDOS PARA GRAVITY FORMS */