spelling changes to theming.md (#24444)

docs/4.0/getting-started/theming.md

@@ -11,7 +11,7 @@ redirect_from: "/docs/4.0/getting-started/options/"
 
 In Bootstrap 3, theming was largely driven by variable overrides in LESS, custom CSS, and a separate theme stylesheet that we included in our `dist` files. With some effort, one could completely redesign the look of Bootstrap 3 without touching the core files. Bootstrap 4 provides a familiar, but slightly different approach.
 
-Now, theming is accomplished by Sass variables, Sass maps, and custom CSS. There's no more dedicated theme stylesheet anymore; instead, you can enable the built-in theme to add gradients, shadows, and more.
+Now, theming is accomplished by Sass variables, Sass maps, and custom CSS. There's no more dedicated theme stylesheet; instead, you can enable the built-in theme to add gradients, shadows, and more.
 
 ## Sass
 
@@ -19,7 +19,7 @@ Utilize our source Sass files to take advantage of variables, maps, mixins, and
 
 ### File structure
 
-Whenever possible, avoid modifying Bootstrap's core files. For Sass, that means creating your own stylesheet that imports Bootstrap so you can modify and extend it. Assuming you've downloaded our source files or are using package manager, you'll have a file structure that looks like this:
+Whenever possible, avoid modifying Bootstrap's core files. For Sass, that means creating your own stylesheet that imports Bootstrap so you can modify and extend it. Assuming you've downloaded our source files or are using a package manager, you'll have a file structure that looks like this:
 
 {% highlight plaintext %}
 your-project/
@@ -150,7 +150,7 @@ Additional functions could be added in the future or your own custom Sass to cre
 
 ### Color contrast
 
-One additional function we include in Bootstrap is the color contrast function, `color-yiq`. It utilizes the [YIQ color space](https://en.wikipedia.org/wiki/YIQ) to automatically return a light (`#fff`) or dark (`#111`) contrast color based the specified base color. This function is especially useful for mixins or loops where you're generating multiple classes.
+One additional function we include in Bootstrap is the color contrast function, `color-yiq`. It utilizes the [YIQ color space](https://en.wikipedia.org/wiki/YIQ) to automatically return a light (`#fff`) or dark (`#111`) contrast color based on the specified base color. This function is especially useful for mixins or loops where you're generating multiple classes.
 
 For example, to generate color swatches from our `$theme-colors` map:
 
@@ -202,7 +202,7 @@ Many of Bootstrap's various components and utilities are built through a series
 
 ### All colors
 
-All colors available in Bootstrap 4, available as Sass variables and a Sass map in our `scss/_variables.scss` file. This will be expanded upon in subsequent minor releases to add additional shades, much like the [grayscale palette](#grays) we already include.
+All colors available in Bootstrap 4, are available as Sass variables and a Sass map in our `scss/_variables.scss` file. This will be expanded upon in subsequent minor releases to add additional shades, much like the [grayscale palette](#grays) we already include.
 
 <div class="row">
   {% for color in site.data.colors %}