Why can't the div nested in div set background-color? in the stylesheet?

like this: 

<div id="container">
    <div id="1st">1</div>
    <div id="2nd">2</div>
    <div id="3rd">3</div>
</div>

when setting the background color through the stylesheet, only the background color of the parent element is displayed 

-sharpcontainer{
        width: 100%;
        height: 100%;
        background-color: red;
    }

and no matter how you set the background color of the child element, it doesn"t work: 

-sharp1st{
        display: block;
        width: 100px;
        height: 100px;
        background-color: black;
    }

the results are as follows:

clipboard.png

clipboard.png

stylebackgound-color:

clipboard.png

Why is this?

Css
Mar.02,2021

https://jsfiddle.net/zhc23bz9/5/

there is a problem with the name of your id. You can change the first id to first. 

-sharpcontainer {
  width: 100%;
  height: 100%;
  background-color: yellow;
}

-sharpfirst {
  display: block;
  width: 100px;
  height: 100px;
  background-color: red;
}

-sharp2nd {
  display: block;
  width: 100px;
  height: 100px;
  background-color: black;
}
<div id="container">
    <div id="first">1</div>
    <div id="2nd">2</div>
    <div id="3rd">3</div>
</div>

in CSS naming conventions, names cannot start with numbers, but only with letters, hyphens, and underscores. It can be followed by letters, hyphens, underscores, or numbers.

Previous: How does Socket tcp server receive data?

Next: After flask modifies the default port

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
© 2021 CodesHelper
Advertising Contact us About us
Menu