Hello,

I prepared a demo https://dojo.telerik.com/EYeYUSUw/6

Also applies to the latest default sass theme but probably to many more.

As you can see, the master grid its 'content row' hover effect is being applied to even the header of the detail grid and there is no way to resolve that unwanted effect apart from adding more styling tedious rules. 

The resolution is so simple:

.k-grid tbody tr:hover, .k-grid tbody tr.k-state-hover {
    background-color: #e6e6ea;
}

Should be

.k-grid tbody > tr:hover, .k-grid tbody > tr.k-state-hover {
    background-color: #e6e6ea;
}

I did not search for the source files/lines what might need to change - easy to find in your current version.

There could be many more of these simple improvements which would save many hours on ours side!

Regards,
Jan