To make your status bar white, add the following meta tag to your HTML template:
<meta name="apple-mobile-web-app-status-bar-style" content="default">
To make your status bar transparent, add the following meta tags to your HTML template instead:
<meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
If you use Bubble, go to your Settings > SEO/metatags > Advanced settings > Script/meta tags in header and paste the code above right before the Progressier script.