If you set
span.wpcf7-list-item -> display:block;

and

input, label, select, textarea -> width: auto;

the problem is resolved.

Now, i want to enjoy this moment to ask you how do you save or use this informations that you collected with custom fields.

Hi, not sure if u type right. input, label, select and textarea are elements and the css define a rule for more than one style by typing them all separeted by comma. So your css should look like this.

input, label, select, textarea {
width: 100%!important;
}
This style is on style.css in line 2523, u could change it there or create a rule that is read after the css that you want to overwrite. As this width is defened with important, i guess you should type important too.

Make sure to create exacly the same rule. Not just label {} or just textarea{} You will get like this.

input, label, select, textarea {
width: auto !important;
}