FoxGuide is a Firefox extension that displays horizontal and vertical guides exactly the Photoshop way. Guides will appear as thin lines that float over the webpage. You can move or remove them just the way you do it Photoshop. Guides are useful for laying out elements symmetrically, structure a design and improving the overall layout.
FoxGuide provides following features:
1. It can restore the guides you created earlier for a particular page even after you close the tab or close the browser.
2. You can change the transparency of the ruler so that the content doesn’t get covered up.
3. You can change the color of the guides depending upon the color scheme of your webpage.
4. You can fix the rulers to the window(viewport) so that they are always visible.
5. The rulers are 10,000px long so you will never fall short of it.
Want to learn more? You can pick up FoxGuide from the Firefox Add-ons website.