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.
