Modifying item-thumbnail Size

How do I go about modifying the size of the default item-thumbnail, I am not to versed in CSS and don’t know how to tackle changing or making my own class. Any help would be appreciated.

EDIT:

This is my ion-item that I wish to modify.

<ion-item class="item-thumbnail-left" href="#/tab/resources/employeerelations">
    <img ng-src="img/resources/employeerelations.png">
    <h2 class="councilTitle">Employee Relations</h2>
</ion-item>

With I title that I removed for purposes of the post. I was able to change the thumbnail size from the browser inspector tool but it would go over the text for the item. How can I change the size of the thumbnail but have the text move according to the size. Thanks

Yes, I have the same issue.

Please, any help?

I have the same need. How can I change the size of a item-thumbnail or item-avatar ?

Thanks