Remove rogue double dash from opacity CSS property name

site/content/tutorial/13-advanced-styling/03-inline-styles/app-a/App.svelte

@@ -10,6 +10,6 @@
 <style>
 	p {
 		font-family: "Comic Sans MS", cursive;
-		background: rgba(255, 62, 0, var(--opacity));
+		background: rgba(255, 62, 0, var(opacity));
 	}
 </style>

site/content/tutorial/13-advanced-styling/03-inline-styles/app-b/App.svelte

@@ -5,11 +5,11 @@
 
 <input type="range" min="0" max="1" step="0.1" bind:value={bgOpacity} />
 
-<p style="color: {color}; --opacity: {bgOpacity};">This is a paragraph.</p>
+<p style="color: {color}; opacity: {bgOpacity};">This is a paragraph.</p>
 
 <style>
 	p {
 		font-family: "Comic Sans MS", cursive;
-		background: rgba(255, 62, 0, var(--opacity));
+		background: rgba(255, 62, 0, var(opacity));
 	}
 </style>

site/content/tutorial/13-advanced-styling/03-inline-styles/text.md

@@ -5,6 +5,6 @@ title: Inline styles
 Apart from adding styles inside style tags, you can also add styles to individual elements using the style attribute. Usually you will want to do styling through CSS, but this can come in handy for dynamic styles, especially when combined with CSS custom properties.
 
 Add the following style attribute to the paragraph element:
-`style="color: {color}; --opacity: {bgOpacity};"`
+`style="color: {color}; opacity: {bgOpacity};"`
 
 Great, now you can style the paragraph using variables that change based on your input without having to make a class for every possible value.

site/content/tutorial/13-advanced-styling/04-style-directive/app-a/App.svelte

@@ -5,11 +5,11 @@
 
 <input type="range" min="0" max="1" step="0.1" bind:value={bgOpacity} />
 
-<p style="color: {color}; --opacity: {bgOpacity};">This is a paragraph.</p>
+<p style="color: {color}; opacity: {bgOpacity};">This is a paragraph.</p>
 
 <style>
 	p {
 		font-family: "Comic Sans MS", cursive;
-		background: rgba(255, 62, 0, var(--opacity));
+		background: rgba(255, 62, 0, var(opacity));
 	}
 </style>

site/content/tutorial/13-advanced-styling/04-style-directive/app-b/App.svelte

@@ -5,11 +5,11 @@
 
 <input type="range" min="0" max="1" step="0.1" bind:value={bgOpacity} />
 
-<p style:color style:--opacity={bgOpacity}>This is a paragraph.</p>
+<p style:color style:opacity={bgOpacity}>This is a paragraph.</p>
 
 <style>
 	p {
 		font-family: "Comic Sans MS", cursive;
-		background: rgba(255, 62, 0, var(--opacity));
+		background: rgba(255, 62, 0, var(opacity));
 	}
 </style>

site/content/tutorial/13-advanced-styling/04-style-directive/text.md

@@ -9,7 +9,7 @@ Change the style attribute of the paragraph to the following:
 ```html
 <p 
 	style:color 
-	style:--opacity="{bgOpacity}"
+	style:opacity="{bgOpacity}"
 >
 ```