Como Centralizar Uma Div
.container {
width: 700px;
margin-left: auto;
margin-right: auto;
}
Blue-eyed Buffalo
.container {
width: 700px;
margin-left: auto;
margin-right: auto;
}<style>
.container {
width: 100vw;
height: 100vh;
background: #6C7A89;
display: flex;
flex-direction: row;
justify-content: center;
align-items: center;
}
.box {
width: 300px;
height: 300px;
background: #fff;
}
body {
margin: 0px;
}
</style>