v6: docs: fix typos, examples, and utility class docs

text would always be white on black background
Update example code for background gradient usage
Update margin utilities docs for v6 spacers
Docs updated to reflect the v6 spacing scale: sizes now range from 0 through 9 (`.m-0`–`.m-9`) and the multiplier values for sizes 3–9 were adjusted.

Negative margin docs were changed to note that v6 only supports negative inline margins (`.ms--1`, `.me--2`) using `-1` and `-2` spacers and that the v5-style full negative utilities (e.g. `.mt-n1`) were removed.

The responsive examples were updated to list `.{breakpoint}m-0` through `.{breakpoint}m-9` and `.{breakpoint}m-auto`.

Author: coliff

site/src/content/docs/utilities/background.mdx

@@ -52,7 +52,7 @@ Do you need a gradient in your custom CSS? Just add `background-image: var(--bs-
 
 <Example class="d-flex flex-column gap-2" code={[
   ...getData('theme-colors').map((themeColor) => `<div class="p-3 bg-${themeColor.name} bg-gradient fg-contrast-${themeColor.name}">.bg-${themeColor.name}.bg-gradient</div>`),
-  `<div class="p-3 bg-black bg-gradient fg-contrast">.bg-black.bg-gradient</div>`
+  `<div class="p-3 bg-black bg-gradient fg-white">.bg-black.bg-gradient</div>`
 ]} />
 
 ## Opacity

site/src/content/docs/utilities/margin.mdx

@@ -17,7 +17,7 @@ import { getData } from '@libs/data'
 
 ## Overview
 
-Use margin utilities to control the outer space around elements. Margin utilities are built from a default Sass map ranging from `.25rem` to `3rem`. Use utilities like `.m-3` and `.m-5` to control the margin on all sides of an element:
+Use margin utilities to control the outer space around elements. Margin utilities are built from a default Sass map ranging from `0` to `3rem` (`.m-0` through `.m-9`). Use utilities like `.m-3` and `.m-5` to control the margin on all sides of an element:
 
 <Example class="d-flex align-items-center justify-content-center gap-4 text-center" showMarkup={false} code={`
   <div class="bd-pattern-diagonal rounded-3">
@@ -65,9 +65,13 @@ Where *size* is one of:
 - `0` - for classes that eliminate the `margin` by setting it to `0`
 - `1` - (by default) for classes that set the `margin` to `$spacer * .25`
 - `2` - (by default) for classes that set the `margin` to `$spacer * .5`
-- `3` - (by default) for classes that set the `margin` to `$spacer`
-- `4` - (by default) for classes that set the `margin` to `$spacer * 1.5`
-- `5` - (by default) for classes that set the `margin` to `$spacer * 3`
+- `3` - (by default) for classes that set the `margin` to `$spacer * .75`
+- `4` - (by default) for classes that set the `margin` to `$spacer`
+- `5` - (by default) for classes that set the `margin` to `$spacer * 1.25`
+- `6` - (by default) for classes that set the `margin` to `$spacer * 1.5`
+- `7` - (by default) for classes that set the `margin` to `$spacer * 2`
+- `8` - (by default) for classes that set the `margin` to `$spacer * 2.5`
+- `9` - (by default) for classes that set the `margin` to `$spacer * 3`
 - `auto` - for classes that set the `margin` to auto
 
 (You can add more sizes by adding entries to the `$spacers` Sass map variable.)
@@ -168,24 +172,23 @@ Bootstrap includes an `.mx-auto` class for horizontally centering fixed-width bl
 
 ## Negative margin
 
-In CSS, `margin` properties can utilize negative values (`padding` cannot). These negative margins are **disabled by default**, but can be enabled in Sass by setting `$enable-negative-margins: true`.
+In CSS, `margin` properties can utilize negative values (`padding` cannot). In v6, negative margins are limited to `margin-inline-start` and `margin-inline-end` only, using spacers `-1` (`-0.25rem`) and `-2` (`-0.5rem`):
 
-The syntax is nearly the same as the default, positive margin utilities, but with the addition of `n` before the requested size. Here’s an example class that’s the opposite of `.mt-1`:
-
-```scss
-.mt-n1 {
-  margin-top: -0.25rem !important;
-}
+```html
+<div class="ms--1">.ms--1</div>
+<div class="me--2">.me--2</div>
 ```
 
+The v5 full negative margin utilities across all sides (like `.mt-n1`) have been removed.
+
 ## Responsive
 
 All margin utilities are responsive and include all breakpoints.
 
 <ul>
 {getData('breakpoints').map((breakpoint) => {
   return (
-    <li><code>.{breakpoint.abbr}m-0</code> through <code>.{breakpoint.abbr}m-5</code> and <code>.{breakpoint.abbr}m-auto</code></li>
+    <li><code>.{breakpoint.abbr}m-0</code> through <code>.{breakpoint.abbr}m-9</code> and <code>.{breakpoint.abbr}m-auto</code></li>
   )
 })}
 </ul>