Rebuilding Blocks via Media Queries in CSS

Let's learn how to rebuild blocks on different screen widths. For example, let's implement the following behavior:

First, let's write the HTML code for our blocks:

<div class="parent">
	<div class="child">1</div>
	<div class="child">2</div>
</div>

Now let's write styles for the parent of our blocks:

.parent {
	display: flex;
	width: 90%;
	margin: 50px auto;
	border: 1px solid red;
}

Now let's write styles for the blocks themselves, without specifying the properties that will be changed by media queries:

.child {
	box-sizing: border-box;
	padding: 20px;
	border: 1px solid green;
}

On large screen widths, let the gap between blocks be calculated automatically:

@media (min-width: 500px) {
	.parent {
		justify-content: space-between;
	}
}

Let's set the width of our blocks to slightly less than 50% to leave some space for indentation:

@media (min-width: 500px) {
	.child {
		width: 49.5%;
	}
}

On a small screen width, we'll place our blocks in a column:

@media (max-width: 500px) {
	.parent {
		flex-direction: column;
	}
}

Let's give them a bottom indent:

@media (max-width: 500px) {
	.child {
		margin-bottom: 10px;
	}
}

Let's put it all together and get the following code:

.parent {
	display: flex;
	width: 90%;
	margin: 50px auto;
}
.child {
	box-sizing: border-box;
	padding: 20px;
	border: 1px solid green;
}

@media (max-width: 500px) {
	.parent {
		flex-direction: column;
	}
	.child {
		margin-bottom: 10px;
	}
}
@media (min-width: 500px) {
	.parent {
		justify-content: space-between;
	}
	.child {
		width: 49.5%;
	}
}

Repeat the example below: