Conditional Formatting - marking the current time on a spreadsheet

Hi There,

I am stuck with a problem! I have a schedule over the course of the day from 04:30 - 01:45 (next day). Time is going in 15 min blocks i.e. 10:00; 10:15; 10:30; 11:00....etc.

I would like a single red line to automatically move along the appropriate cell as the day goes along. I have manually created what it is roughly that I want, with cell B5 showing the current time using the =NOW() formula. Please see image below.

There is a formula that does one for days of the week (not time/minutes) with the formula (assuming cell D4 is the first cell of the days)
=IF(D$4=TODAY(), TRUE, FALSE)
This works perfectly - I can format for there to be just one single red line and the line goes far down the spreadsheet - up until where I had highlighted.

But I want this line to be moving every 15 minutes. Not even hourly.

When I tried this formula:
=HOUR(A2)=HOUR(NOW())
this was close, but it showed 3 red lines (for each 15 min cell) as it was covering over the course of the hour, understandably. Also, the red line would only cover the height of the single time cell - I wanted the line to extend downwards (like in the attached image).

Is there a formula I can use that will mark one long line for every 15 minutes?
Conditional Formatting 15 MINS.JPG
Thank you!

Incredible!

Thank you so much!

I had the same problem but transposed and highlighted. This worked perfectly.

Thank you!