theme-color
The theme-color value for the name attribute of the <meta> element indicates a suggested color that user agents should use to customize the display of the page or of the surrounding user interface. If specified, the content attribute must contain a valid CSS <color>.
Example
<meta name="theme-color" content="#4285f4">
The following image shows the effect that the <meta> element above will have on a document displayed in Chrome running on an Android mobile device.
  
Image credit: from Icons & Browser Colors, created and shared by Google and used according to terms described in the Creative Commons 4.0 Attribution License.
You can provide a media type or query inside the media attribute; the color will then only be set if the media condition is true. For example:
<meta name="theme-color" media="(prefers-color-scheme: light)" content="white"> <meta name="theme-color" media="(prefers-color-scheme: dark)" content="black">
Specifications
| Specification | 
|---|
| HTML Standard (HTML) # meta-theme-color | 
Browser compatibility
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
| theme-color | 73 Chrome uses the color only on installed progressive web apps. 39-72 Chrome reports support, but does not actually use the color anywhere. | 79 Edge uses the color only on installed progressive web apps. | No | No | No | 15 | No | 80 Chrome for Android does not use the color on devices with native dark mode enabled. | No | No | 15 | 6.2 | 
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    https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta/name/theme-color