I took a look into the codes.
the heartgif-code has a lot of delays and you added the strips_loop(); function only one time at the end.
the “quick and dirty without learning to code-way”
is to insert the call of strips_loop(); after each block of “display”-commands
Though it might be still not the same look and feel as the display-commands have a delay-command after each block
So the LED-code gets distracted.
To make it smooth again there are two basic ways:
1.) replacing work through money: buying a second arduino and kep the codes seprated
2.) working your way through learning how to code with millis() for non-blocking timing and learning how to code a statemachine
best regards Stefan