<!DOCTYPE html>
<html>
<head>
<title>Заголовок документа</title>
<style>
body {
background: #ccc;
font-size: 20px;
text-align: center;
}
main div {
display: flex;
align-items: center;
justify-content: center;
color: black;
padding-top: 30px;
padding-bottom: 30px;
width: 200px;
height: 100px;
margin: 15px;
font-weight: bold;
border: solid;
}
.flex-center {
display: flex;
justify-content: center;
}
/* border-top-width example classes */
.b1 {border-top-width: medium;}
.b2 {border-top-width: thin;}
.b3 {border-top-width: thick;}
.b4 {border-top-width: 10px;}
.b5 {border-top-width: initial;}
.b6 {border-top-width: inherit;}
</style>
</head>