Fix for narrow white piano key width

[marcustrp]

Quick fix for piano keys being too narrow:

Change value of width from 171% to 178%:

.content-body .Key.white .piano-key {
width: 178%;
}

[marcustrp]

[ceciliabjork]

@saxjax @MartinBruun Did you see this? Would it work for the E-F gap as well?