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

Code Example 1

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

.class {
  border-radius: 4px;
}

.circle {
  border-radius: 50%;
}

Code Example 2

/* Use border-radius property */

.class {
  border-radius: 5px;
}

.circle {
  border-radius: 50%;
}

Code Example 3

#rcorners {
  border-radius: 25px;
}

Code Example 4

.div { /*Top Left (TL) Top Right (TR) Bottom Right (BR) Bottom Left (BL)*/
	border-radius: 15px 50px 30px 5px; /*TL TR BR BL*/
  	border-radius: 15px 50px 30px; /*TL TRBL BR*/
  	border-radius: 15px 50px; /*TLBR TRBL*/
  	border-radius: 15px; /*All corners*/
}

Code Example 5

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

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