**`fa-symbol`**[`-regular`|`-solid`|`-brands`]**`.css`**
+ CSS variable `--fa-symbol` is set by classes.
+ The variable can be used with `var(--fa-symbol)` which is predefined for some element and class combinations:
* **(`dt`|`dd`|`li`)**`.fa`[`r`|`s`|`b`] use `list-style-image`
* **`.i`**`.fa`[`r`|`s`|`b`] uses `background-image`
* **`.a`**`.fa`[`r`|`s`|`b`] uses `content` *after* element content
* **(`.b`|`i`)**`.fa`[`r`|`s`|`b`] use `content` *before* element content
* **`summary`**`.fa`[`r`|`s`|`b`] use `content` for *marker* box
