box sizing

<html><head><title>box sizing</title><style> .b1{ width: 200px; border: 40px solid black; padding: 30px; box-sizing: border-box; margin-bottom:10px; } .b2{ width: 200px; border: 30px solid black; padding: 30px; box-sizing: border-box; margin-bottom:10px; } .b3{ width: 200px; border: 20px solid black; padding: 30px; box-sizing: border-box; margin-bottom:10px; } .b4{ width: 200px; border: 10px solid black; padding: 30px; box-sizing: border-box; margin-bottom:10px; } </style></head><body> <div class="b1">Lorem ipsum dolor sit amet.</div> <div class="b2">Lorem ipsum dolor sit amet.</div> <div class="b3">Lorem ipsum dolor sit amet.</div> <div class="b4">Lorem ipsum dolor sit amet.</div> </body></html>