Since Expanded Tile resides in your page instead of Nosto's UGC Widget iframe, you will need to put your customized stylesheet in your own page, not via the Nosto Admin Portal.
The following snapshot illustrates the style of default Expanded Tile.
HTML Structure
A Shopspot element (.stacklapopup-shopspot) wraps both icon (.stacklapopup-shopspot-icon) and flyout (.stacklapopup-shopspot-flyout). The following diagram shows detailed HTML structure with CSS class names.
The following is the sample HTML source code, which has the same architecture with the above diagram.
Our default style restricts the dimension to 46x46 and sets overflow:hidden style so the user can't see the flyout by default. When the user hovers to an icon, the hover class (.stacklapopup-shopspot-hover) will be attached which sets overflow: visible and displays the flyout.
Sample CSS
By pasting the following code into one of stylesheets of your website, you can get the above customized style.
The default style sets top: -24px; and left: calc(100% -24px); so that Shopspot flies from top-right corner. The default Shopspot dimension is 24px * 24px.
Flying from Left-Top Corner
You can simply change the top and left properties to -24px to make it flying from top-left corner.