Style rules are the foundation of Sass, just like they are for CSS. And they work the same way: you choose which elements to style with a selector, and [declare properties](../style-rules/declarations) that affect how those elements look.
But Sass wants to make your life easier. Rather than repeating the same
selectors over and over again, you can write one style rules inside another.
Sass will automatically combine the outer rule's selector with the inner rule's.
{% endmarkdown %}
{% codeExample 'nesting' %}
nav {
ul {
margin: 0;
padding: 0;
list-style: none;
}
li { display: inline-block; }
a {
display: block;
padding: 6px 12px;
text-decoration: none;
}
}
===
nav
ul
margin: 0
padding: 0
list-style: none
li
display: inline-block
a
display: block
padding: 6px 12px
text-decoration: none
{% endcodeExample %}
{% headsUp %}
Nested rules are super helpful, but they can also make it hard to visualize how much CSS you're actually generating. The deeper you nest, the more bandwidth it takes to serve your CSS and the more work it takes the browser to render it. Keep those selectors shallow!
{% endheadsUp %}
{% markdown %}
### Selector Lists
Nested rules are clever about handling selector lists (that is, comma-separated
selectors). Each complex selector (the ones between the commas) is nested
separately, and then they're combined back into a selector list.
{% endmarkdown %}
{% codeExample 'selector-lists' %}
.alert, .warning {
ul, p {
margin-right: 0;
margin-left: 0;
padding-bottom: 0;
}
}
===
.alert, .warning
ul, p
margin-right: 0
margin-left: 0
padding-bottom: 0
{% endcodeExample %}
{% markdown %}
### Selector Combinators
You can nest selectors that use [combinators][] as well. You can put the
combinator at the end of the outer selector, at the beginning of the inner
selector, or even all on its own in between the two.
Sass only parses selectors *after* interpolation is resolved. This means you can safely use interpolation to generate any part of the selector without worrying that it won't parse.
You can combine interpolation with the parent selector `&`, the [`@at-root` rule][], and [selector functions][] to wield some serious power when dynamically generating selectors. For more information, see the [parent selector documentation][].