Theme-color Meta Tag

The theme-color meta tag can be used by web browser to customize the color of the webpage or surrounding user interface elements. The meta tag should contain a valid CSS color which can be specified with a hex value, an rgb() value or any other valid css color value.

Example: <meta name="theme-color" content="#4285f4" />

Support for this meta tag is spotty. Some browsers only do anything with the color when the webpage is installed as a progressive web app. In addition, the theme-color can conflict with "dark-mode" or "night-mode" coloring offered by some web browsers. When it does work, it is usually used to provide the background color or tint for the URL bar and navigation buttons.