dans admin/structure/types/manage/article/fields/field_images_insert

cliquer sur insérer et

Classes CSS additionnelles

field-type-image-pas-float

dans themes/corporateclean/styles.css

après

img { max-width: 100%; height: auto; float: left;
-webkit-box-sizing: border-box; -moz-box-sizing: border-box; box-sizing: border-box; }

rajouter

img.float, .field-type-image-pas-float { max-width: 100%; height: auto; float: none;  
-webkit-box-sizing: border-box; -moz-box-sizing: border-box; box-sizing: border-box; }