block alignment
<body>
<div class="box"></div>
</body>.box {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
background: #000;
color: #fff;
width: 300px;
height: 200px;
}<body>
<div class="box"></div>
</body>.box {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
background: #000;
color: #fff;
width: 300px;
height: 200px;
}
Всемирная паутина
Пример
Flexbox Froggy
