To have a best layout of this widget on "Rezo" theme, you may want a layout like this

To do that, simply put this code to "Custom CSS" on the configuration page:

{xmt_id}.xmt .tweet_avatar {
    padding: 3px !important;
    background: #fff !important;
    border: solid 1px #ccc !important;
    -webkit-box-shadow: 0 1px 2px rgba(0,0,0,.1);
    -moz-box-shadow: 0 1px 2px rgba(0,0,0,.1);
    box-shadow: 0 1px 2px rgba(0,0,0,.1);
    -webkit-border-radius: 4px;
    -moz-border-radius: 4px;
    border-radius: 4px;
    float: left;
    margin-right: 12px;
    padding-top: 3px;
}

{xmt_id}.xmt .ul li.tweet_list {
    font:inherit;
    text-indent:0;
    background: none;
    display:block;
    white-space: normal;
    word-wrap: break-word;
    color:inherit;
    padding: 6px 0  !important;
}

This solution was originally posted by John Larkin