All theme margins ruined

PLEASE HELP the themes on my site https://www.housenav.com/ somehow all messed up.

This happens after I tried to change the CSS of my Geodirectory plugin.
Below is the steps I have done in order to center my GD search bar :

1)Geodirectory > Design > Scripts > Custom Style CSS > paste

.geodir-search {
    border: none;
    float: none;
    margin: 0 auto;
    width: 400px;
}

I am currently using wordpress Tonic theme and the site became wider/centered, the title and content is not align side to side like the original theme I installed initially.

When I tried changing to any other themes, some happened to have borders exist at both side of my webiste, and some just have the post contents stick to the edge of the site.

Even if I delete the script and save it the problem still remains the same.