Increase toast max-width

This makes it big enough to fit the compiler error message

    IndentationError: unindent doesn't match any outer indent level

If we still have problems with overflow we should probably look at
ways to wrap <pre> text instead of making this wider.

src/index.scss

@@ -37,6 +37,7 @@ body {
 
 .#{$ns}-toast {
     user-select: text;
+    max-width: 700px;
 }
 
 .#{$ns}-button {