use wrapper for the block math content

The class `equation-wrapper` should have the attribute `overflow-x: auto;` so that the equation would have a scroll bar. Note that this only works for a block equation.

Author: samimaattaCelia

Guidelines/Nordic MathML Guidelines 2024-1.md

@@ -617,31 +617,35 @@ Notice that `columnspan` is written this way, because of backwards compatability
 
 It is common to label equations and then reference these equations later on in mathematical text.
 
-Example markup for a equation with a label:
+Example markup for a block equation with a label:
 
 ```html
-<math id="eq-1-3">
-    <mo>(</mo>
-    <mi>a</mi>
-    <mo>∘<!-- ∘ --></mo>
-    <mi>b</mi>
-    <mo>)</mo>
-    <mo>∘<!-- ∘ --></mo>
-    <mi>c</mi>
-    <mo>=</mo>
-    <mi>a</mi>
-    <mo>∘<!-- ∘ --></mo>
-    <mo>(</mo>
-    <mi>b</mi>
-    <mo>∘<!-- ∘ --></mo>
-    <mi>c</mi>
-    <mo>)</mo>
-    <mspace width="5em">
-    <mtext>(1.3)</mtext>
-</math>
+<div class="equation-wrapper">
+    <math display="block" id="eq-1-3">
+        <mo>(</mo>
+        <mi>a</mi>
+        <mo>∘<!-- ∘ --></mo>
+        <mi>b</mi>
+        <mo>)</mo>
+        <mo>∘<!-- ∘ --></mo>
+        <mi>c</mi>
+        <mo>=</mo>
+        <mi>a</mi>
+        <mo>∘<!-- ∘ --></mo>
+        <mo>(</mo>
+        <mi>b</mi>
+        <mo>∘<!-- ∘ --></mo>
+        <mi>c</mi>
+        <mo>)</mo>
+        <mspace width="5em">
+        <mtext>(1.3)</mtext>
+    </math>
+</div>
 ```
 
 It is required that a labeled equation has
+- a `<div>` wrapper with the class `equation-wrapper`
+- the `<math>` has the attribute `display="block"`
 - an ID based on the `<mtext>` label and the ID is in the `<math>` element
 - `<mspace>` for spacing before the label
 - label in `<mtext>`.