- 'light-square': (i+j)%2==0 && (this.expert || !highlight),
- 'dark-square': (i+j)%2==1 && (this.expert || !highlight),
- 'highlight': !this.expert && highlight,
- 'incheck': !this.expert && incheckSq[ci][cj],
+ 'light-square': (i+j)%2==0,
+ 'dark-square': (i+j)%2==1,
+ 'highlight': showLight && !!lm && _.isMatch(lm.end, {x:ci,y:cj}),
+ 'incheck': showLight && incheckSq[ci][cj],