Check out example codes for "border radius css". It will help you in understanding the concepts better.

Code Example 1

border-radius: 5px; /* The corners will be round */

Code Example 2

#rcorners {
  border-radius: 25px;
}

Code Example 3

-webkit-border-radius: 5px;
-moz-border-radius: 5px;
border-radius: 5px;

Code Example 4

.abcclass {
  border-radius: 0px;  // for no radius
  
}

Code Example 5

/* Set rounded corners with border-radius property */

.class {
  border-radius: 4px;
}

.circle {
  border-radius: 50%;
}

Code Example 6

element:focus{border-radius:25px;}

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