Check out example codes for "theme colur in html". It will help you in understanding the concepts better.

Code Example 1

<!-- Theme-color is use to set the background to your favorite/Branding color
Add two attribute in meta tag first 'name="theme-color"' and second 'content="Your Hexadecimal Code"'
Add Below Meta property to your HTML code in HEAD Section -->
  <meta name="theme-color" content="#444444">

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