Browser Back button functionality

href="#" onClick="history.go(-1); return false;" class="btnCss"  Back

how to add/remove css class from a dom element

http://www.mzcart.com/javascript-how-to-addremove-css-class-from-a-dom-element/

Error occurred in deployment step ‘Add Solution’: A feature with ID has already been installed in this farm

http://msbuzzz.wordpress.com/2011/09/07/error-occurred-in-deployment-step-add-solution-a-feature-with-id-has-already-been-installed-in-this-farm/