fix(css): Fix flex: 1 explanation (#37553)

* fix(css): Fix `flex: 1` explanation

* Update files/en-us/web/css/css_flexible_box_layout/basic_concepts_of_flexbox/index.md

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* remove line break

* Update files/en-us/web/css/css_flexible_box_layout/basic_concepts_of_flexbox/index.md

Co-authored-by: Chris Mills <[email protected]>

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Chris Mills <[email protected]>

Author: 3 people

files/en-us/web/css/css_flexible_box_layout/basic_concepts_of_flexbox/index.md

@@ -292,7 +292,7 @@ Using `flex: auto` is the same as using `flex: 1 1 auto`; this is similar to `fl
 
 Using `flex: none` will create fully inflexible flex items. It is as if you wrote `flex: 0 0 auto`. The items cannot grow or shrink and will be laid out using flexbox with a `flex-basis` of `auto`.
 
-The shorthand you often see in tutorials is `flex: 1` or `flex: 2` and so on. This is the same as writing `flex: 1 1 0` or `flex: 2 1 0` and so on, respectively. The items can grow and shrink from a `flex-basis` of `0`.
+The shorthand you often see in tutorials is `flex: 1` or `flex: 2` and so on. This is the same as writing `flex: 1 1 0` or `flex: 2 1 0` and so on, respectively. The items get minimum size due to `flex-basis: 0` and then proportionally grow to fill the available space. In this case, the `flex-shrink` value of `1` is redundant because the items start with minimum size — they're not given any size that could cause them to overflow the flex container.
 
 Try these shorthand values in the live sample below.