Immaculate & Vivid Yellow от Nicholas Costa

Why It's Better
Numerous themes omit those extra and precise details, but this theme has it covered. While relatively plain, it's certainly not boring as the subtle elements of vivid yellow add clarity to your browsing experience. When searching using the address bar, the yellow will outline the drop-down showing the suggestions and previous searches. When opening the popup menu to customize the toolbar or adjust Firefox's settings, the yellow will outline the menu. When saving, editing or viewing your bookmarks in the menu or sidebar, the yellow will border. Even the loading animation displayed whilst a tab loads will be yellow. And of course, the tab highlight it a bold yellow. Behind the toolbar is a simplistic pattern of askew vertical grey bars to eliminate dull characteristics and to shake things up a bit. It adds a slight element of playfulness and attractiveness. This theme is bright and precise without being unnecessary, it's subtle, delicate and elegant.