Why do my CSS media queries not work on all mobile devices?

This leads to the interesting question how developers can find out via JavaScript if a media query is supported and understood at all by a browser.

Media queries are: logical if statements. “If” these things are true about the browser, use the CSS inside.

Media queries are case-insensitive. Media types define the broad category of device for which the media query applies: all , print , screen . Media · Testing media queries · Reduced motion · Width

I am trying to complete my assignment which requires the creation of a responsive web design using media queries for the following ranges of the viewport ...

Media Queries Basic​. 透過 @media 可以用來定義要套用的. 媒體類型（Media Type）：可用的類型包含 all (default) , print , screen 和 speech 。 Media Queries Basic · 其他設定 · 載入不同的CSS 檔 · 實用範例

I am attempting to use CSS media queries to change the appearance of my website on mobile and smaller screen sizes, but only some devices (some phones work, ...

My media query does not override the regular CSS unless I use !important all the time. What's the error? Here you can see the CSS with the !

The not keyword inverts the meaning of a single media query. Media types describe the general category of a device.

Everytime I check different screen sizes my media query does not change. I can provide the html code if needed but it does not respond to my pixel changes.

The CSS @media rule is used in media queries to apply different styles for different media types/devices.