Coach marks or help info for browser including desktop, mobile, as well as ipad/tablet

We are working on Web portal development and have a requirement of developing generic help overlays & coach marks which will be shown on demand. Kindly provide some pointer if there is hands on experience with below requirements. - Help overlays should not be a static images for each resolution and screen size, because we want to avoid bundling numerous overlays in the Web App. - Help overlays should be programmable in terms of changing the text on it so that multiple language support can be given without bundling language specific help images. - The Web portal has a component with many sub sections in it. Each subsection when opened should show help overlay specific to it and should adjust according to scrolling, and resolution, since it would be viewable on desktop, mobile as well as tablet browsers.