Not issue, just fixed columns width...

[mrquarter81]

I added these css properties to make years columns equal width...
Thanks for you code.

.timesheet .scale {
height: 100%;
width: 100%;
display: table;
table-layout: fixed;
}
.timesheet .scale section {
min-width: 10%;
display: table-cell;
text-align: center;
height: 100%;
}
.timesheet .data {
overflow: hidden;
margin-top: 50px;
}