coding for website mouseover feature

I am using squarespace for an on-line ecommerce retail store website. Squarespace provides (and supports) a selection of templates and styling options with a user interface requiring no software skills. However, they do allow custom css options. I am reasonably techie, but have no css etc. skills. My intention is to job out any customization I want for the site. My first project is the coding needed to make a button or logo enlarge in size when rolled over. I do not want any animation, which should keep complexity down. I may want some styling change such as color. My sense of this is that I simply have 2 versions of the icon/button and a rollover just displays the second image. Besides the actual code, I will need it to be added to my site, through squarespace adding code procedures. To bid this job, the provider will need to be familiar (or go check it out now) with the squarespace model. Please do not reply unless you are comfortable with adding code to a squarespace template, and of course know how to do rollover/mouseover stuff. There is lots of need for squarespace coding support skills, my advice would be for anyone interested in this kind of work to get up to speed, and advertise on squarespace. They provide a place for folks to do this. If you can be skillful (and therefore efficient) you can probably keep costs reasonable and get work adding code for people to tweak stuff. I will provide a link to a practice site I have on squarespace to experiment with for solutions.