Why do we need to include rotate -45deg in the keyframe

Tell us what’s happening:
Describe your issue in detail here.

I want to know why we need to include ‘rotate(-45deg)’ in the keyframes named beat. I tried taking them out and the resulting animation re-rotate every time the animation loop.

Didn’t we already initially make it rotate -45 degrees in the heart class by putting ‘rotate(-45deg)’ in the .heart class?

So my question is, why doesn’t the heart just stay in the upright position every time the animation loop if we take out the ‘rotate(-45deg)’ code in the keyframes named beat.

  **Your code so far**

<style>
.back {
  position: fixed;
  padding: 0;
  margin: 0;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: white;
  animation-name: backdiv;
  animation-duration: 1s;

}

.heart {
  position: absolute;
  margin: auto;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background-color: pink;
  height: 50px;
  width: 50px;
  transform: rotate(-45deg);
  animation-name: beat;
  animation-duration: 1s;

}
.heart:after {
  background-color: pink;
  content: "";
  border-radius: 50%;
  position: absolute;
  width: 50px;
  height: 50px;
  top: 0px;
  left: 25px;
}
.heart:before {
  background-color: pink;
  content: "";
  border-radius: 50%;
  position: absolute;
  width: 50px;
  height: 50px;
  top: -25px;
  left: 0px;
}

@keyframes backdiv {
  50% {
    background: #ffe6f2;
  }
}

@keyframes beat {
  0% {
    transform: scale(1) rotate(-45deg);
  }
  50% {
    transform: scale(0.6) rotate(-45deg);
  }
}

</style>
<div class="back"></div>
<div class="heart"></div>
  **Your browser information:**

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:94.0) Gecko/20100101 Firefox/94.0

Challenge: Make a CSS Heartbeat using an Infinite Animation Count

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