Shorten space widths to multiples of 0.35ex

**Output changes**

- Spaces are significantly shorter. Specifically a multiple of 0.35ex
  instead of 1ex.

Resolves: #102

docs/index.html

@@ -1416,8 +1416,10 @@ <h3>Spaces</h3>
           <p>
             MathML has an element called <code>&lt;mspace&gt;</code>. Two or
             more spaces in a row will be translated into that element where it
-            makes sense. The width of the element will be
+            makes sense. The width of the space will be
             <math>
+              <mn>0.35</mn>
+              <mo>&#x2062;</mo>
               <mrow>
                 <mo fence="true">(</mo>
                 <mrow>
@@ -1427,10 +1429,9 @@ <h3>Spaces</h3>
                 </mrow>
                 <mo fence="true">)</mo>
               </mrow>
-              <mi>ex</mi>
-            </math>
+            </math> <span class="unit">ex</span>
             where <math><mi>n</mi></math> is the number of subsequent spaces and
-            <math><mi>ex</mi></math> is the height of the <i>‘x’</i>
+            <span class="unit">ex</span> is the height of the <i>‘x’</i>
             character in your font.
           </p>
 

src/compiler/parser/handlers/space.js

@@ -13,7 +13,7 @@ export default function space({ start, tokens }) {
   const { length } = token.value;
   const attrs = blockSpace
     ? { depth: `${length}em` }
-    : { width: `${length - 1}ex` };
+    : { width: `${0.35 * (length - 1)}ex` };
 
   return {
     node: {