```
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Flex Box</title>
<link rel="stylesheet" href="">
<style>
html,
body {
margin: 0;
padding: 0;
width: 100%;
}
.container {
width: 90vw;
height: 90vh;
margin: 10px auto;
display: flex;
flex-direction: row;
justify-content: space-between;
align-items: stretch;
border: 10px solid black;
}
.box {
width: 100px;
font-size: 50px;
color: #fff;
text-align: center;
padding: 10px;
box-sizing: border-box;
}
.box-1 {
background: darkblue;
}
.box-2 {
background: darkcyan;
}
.box-3 {
background: darkgoldenrod;
}
.box-4 {
background: darkmagenta;
}
</style>
</head>
<body>
<div class="container">
<div class="box box-1">1</div>
<div class="box box-2">2</div>
<div class="box box-3">3</div>
<div class="box box-4">4</div>
</div>
</body>
</html>

```

Hi everybody! I've been learning flex box but I'm having a problem with this particular example. There's a thin white space between the border and the elements, like a thin margin. I don't know why is it there and how to remove it. Can somebody help me, please?

EDIT: I'm not refering to the space-between propery, I want it, but there is a thin margin going from top to bottom, left and right that shouldn't be there