Added explicit `box-sizing: content-box;` for the `.tl-slide-content` (#787)
Added explicit `box-sizing: content-box;` for the `.tl-slide-content` (#787)

Co-authored-by: OleksandrDanylchenko <22bd633a058d60b0929394ecd18081ab4db3e346@gmail.com>
NUKnightLab/TimelineJS3,NUKnightLab/TimelineJS3,NUKnightLab/TimelineJS3