flexbox space between

justify-content: space-between;

justify-content: flex-start | flex-end | center | space-between | space-around | space-evenly

.upper
{
  margin:30px;
  display:flex;
  flex-direction:row;
  width:300px;
  height:80px;
  border:1px red solid;

  padding:5px; /* this */
}

.upper > div
{
  flex:1 1 auto;
  border:1px red solid;
  text-align:center;

  margin:5px;  /* and that, will result in a 10px gap */
}

.upper.mc /* multicol test */
{flex-direction:column;flex-wrap:wrap;width:200px;height:200px;}

/* Flex */
.anyclass {
	display:flex;
}
/* row is the Default, if you want to change choose */
.anyclass {
	display:flex;
 	flex-direction: row | row-reverse | column | column-reverse;
}

.anyclass {
  /* Alignment along the main axis */
  justify-content: flex-start | flex-end | center | space-between | space-around | space-evenly | start | end | left | right ... + safe | unsafe;
}

.container {
  justify-content: flex-start | flex-end | center | space-between | space-around | space-evenly | start | end | left | right ... + safe | unsafe;
}

.container {
	display: flex;
}

Anything within the container that is a block level element is
now turned into an inline element only taking up the space of 
its actual content placing all items side by side instead on
individual rows.