Time, duration, midnight - iWork Numbers

I have this table in Numbers: In the first column I want to calculate the differences between the timestamps in the third column. The first four entries in the first column are fine. I just subtract the previous row from the current row (e.g., =C3-C2), but that doesn't work when going past midnight between row 4 and 5. If I use the same formula as above I get a negative value because 01:31 is less than 23:12. I tried adding 24h or 1d etc to that calculation, but it returned unexpected results. If I used DUR2HOURS, as seen in the screenshot, I can add 24 and get a valid result but instead the number format in the cell is, as you can see, screwed up. I have tried changing the cells format from automatic to time or duration, but it just, automatically, reverts to automatic. Adding 24 is stupid because it requires me to manually do that for every midnight in the table. **How do I handle midnight as well as fix the format of the time difference in the first column?** The end goal is to plot the values in the second column (12,3 etc) against the their "relative" timestamp. That is, 12,3 starts at zero on the x-axis, the first 12,7 at 3h 41m on the x-axis, the second 12,7 at 4h 08m (3h41m + 27m) on the x-axis etc. In other words, the distance on the x-axis is irregular.