regex that captures optional property in style attribute

I have the following 2 strings:

<span id="1-1" role="presentation" dir="ltr" style="left: 72px; top: 87.8641px; font-size: 11px; font-family: sans-serif; transform: scaleX(0.999349);">&lt;span&gt;&lt;/span&gt;</span>

<span id="1-2" role="presentation" dir="ltr" style="left: 72px; top: 102.41px; font-size: 11px; font-family: sans-serif;">&lt;div&gt;&lt;/div&gt;</span>

I have a regex that captures the left and top values in the style attribute.
However, there is also a transform property that is optional, and I’d like to capture it if it exists.

Here’s what I came up with:

<span id="1-[1|2]".*?left:s(.*?)px.*?top:s(.*?)px.+?(transform:sscaleX((.*)))?.+?(?=">)

However, the value inside of scaleX(...) is not being captured.
Any thoughts on what to do?