Ah yes I see it used to return:

```html
<div className="grid-item one-whole large-one-quarter patient-data-subnav-left">
  {left}
</div>
<div className="grid-item one-whole large-two-quarters patient-data-subnav-center">
  {center}
</div>
<div className="grid-item one-whole large-one-quarter patient-data-subnav-right">
  {right}
</div>
```

And now it's just:

```html
  {left}
<div className="grid-item one-whole large-two-quarters patient-data-subnav-center">
  {center}
</div>
  {right}
```

Still not sure the reason for that though? Originally, it didn't matter if `left` and `right` were null, it would just be an empty space and `center` with the "Patient data" title would be centered?

But yes, as far as layout is concerned, it can be a bit tricky, so don't worry about it too much for now. Get it to work and we can revisit later :)