Nowadays most of the websites are responsive websites. This makes your site looks great on mobile devices. However, it still looks and feels like a website. Matching the color of address bar to your website, gives it a native app-like feel. This improves user experience.
Simply add the below meta tag to head section of your page.
<!-- Chrome, Firefox OS, Opera--> <meta name="theme-color" content="#4285f4"> <!-- Windows Phone --> <meta name="msapplication-navbutton-color" content="#4285f4"> <!-- iOS Safari --> <meta name="apple-mobile-web-app-status-bar-style" content="#4285f4">
The content field has the hex code for the color you want to use as theme color.