Animation is different from one in Codepen

Question

The CSS animation here on my website is missing some features from the Codepen example such as the smoke and there is gaps in between some parts of the train. The code used is identical except I have to decompile the SASS to CSS before I put it into Shopify. And here is the Codepen link

body {
  background: linear-gradient(90deg, #1A2980 10%, #26D0CE 90%);
  height: 100vh;
  width: 100vw;
  display: -webkit-box;
  display: flex;
  align-items: center;
  justify-content: center;
}

.toy-train {
  position: relative;
  width: 11vw;
}

.engine {
  float: right;
  position: relative;
}

.window {
  height: 2.8vw;
  width: 3vw;
  background-color: #194488;
  position: relative;
  border: .3vw solid #000;
}

.window:before,
.window:after {
  content: "";
  position: absolute;
  left: 50%;
  border: .3vw solid #000;
}

.window:before {
  height: .7vw;
  background-color: #F82510;
  width: 4.5vw;
  margin-top: -1.3vw;
  margin-left: -2.6vw;
  border-radius: .8vw;
}

.window:after {
  margin-left: -.8vw;
  margin-top: .3vw;
  border-radius: 50%;
  height: 1.1vw;
  width: 1.1vw;
  background-color: #fff;
}

.engine-main {
  height: 1vw;
  width: 3.5vw;
  border: .3vw solid #000;
  background-color: #3D9A01;
  position: absolute;
  border-radius: 0 .8vw .8vw 0;
  right: -4.1vw;
  bottom: -.3vw;
}

.engine-main:before {
  content: "";
  height: 1vw;
  width: .8vw;
  background-color: #000;
  position: absolute;
  top: -1.1vw;
  left: .4vw;
  transform: rotate(180deg);
  border-radius: 50% 50% 50% 50% / 90% 90% 40% 40%;
}

.engine-main:after {
  content: "";
  height: 1.2vw;
  width: .8vw;
  position: absolute;
  display: block;
  right: .5vw;
  top: -1.8vw;
  border-radius: 50% 50% 50% 50% / 90% 90% 40% 40%;
  transform: rotate(180deg);
  z-index: -1;
  background-color: #194488;
  border: .3vw solid #000;
}

.engine-body {
  height: 1.7vw;
  width: 7.5vw;
  position: absolute;
  left: -.2vw;
  top: 3.0vw;
  background-color: #F69F00;
  border: .3vw solid #000;
  border-radius: .5vw;
}

.engine-body .big-wheel {
  top: .3vw;
  left: .2vw;
}

.engine-body .normal-wheel {
  left: 4.5vw;
  top: .5vw;
}

.engine-body:before {
  content: "";
  position: absolute;
  height: .5vw;
  width: .5vw;
  left: -1.1vw;
  bottom: .2vw;
  z-index: -1;
  background-color: #fff;
  border-radius: 50%;
  border: .3vw solid #000;
}

.wheels>div {
  position: absolute;
  background-color: #F82510;
  border-radius: 50%;
  border: .3vw solid #000;
  animation: wheel-rotate 1s linear infinite;
}

.wheels>div:before {
  content: "";
  position: absolute;
  width: 100%;
  border-bottom: .1vw solid #000;
  top: 50%;
  margin-top: -.1vw;
}

.wheels>div:after {
  content: "";
  height: .8vw;
  width: .8vw;
  position: absolute;
  background-color: #000;
  border-radius: 50%;
  left: 50%;
  top: 50%;
  margin-left: -.4vw;
  margin-top: -.4vw;
}

.wheels .big-wheel {
  width: 2.2vw;
  height: 2.2vw;
  animation-delay: -0.3s;
}

.wheels .normal-wheel {
  height: 2.0vw;
  width: 2.0vw;
  animation-delay: -0.6s;
}

.locomotive {
  height: 3.5vw;
  width: 6.0vw;
  border: .3vw solid #000;
  background-color: #F69F00;
  border-radius: .5vw;
  position: relative;
  float: left;
  margin-top: 1.3vw;
}

.locomotive:before {
  content: "";
  width: 100%;
  background: linear-gradient(to right, #000000 0%, #000000 8%, #f69f00 8%, #f69f00 15%, #000000 15%, #000000 28%, #000000 34%, #f69f00 34%, #f69f00 65%, #000000 65%, #000000 65%, #000000 100%);
  height: .3vw;
  position: absolute;
  top: .6vw;
  left: 0;
}

.locomotive:after {
  content: "";
  width: 100%;
  background: linear-gradient(to right, #000000 0%, #000000 24%, #f69f00 24%, #f69f00 65%, #f69f00 65%, #000000 65%, #000000 85%, #f69f00 85%, #f69f00 90%, #000000 90%, #000000 100%);
  height: .3vw;
  position: absolute;
  top: 1.4vw;
  left: 0;
}

.locomotive .wheels>div {
  top: 2.2vw;
  animation-delay: -0.6s;
}

.locomotive .wheels>div:first-child {
  animation-delay: -0.9s;
}

.locomotive .normal-wheel:first-of-type {
  left: .2vw;
}

.locomotive .normal-wheel:last-of-type {
  right: .2vw;
}

.locomotive .trash {
  height: 3.5vw;
  width: 5.0vw;
  position: absolute;
  top: -1.8vw;
  border: .3vw solid #000;
  background-color: #3D9A01;
  border-radius: 50%;
  left: .2vw;
  z-index: -1;
}

.tracks {
  position: relative;
  width: 20vw;
  bottom: -1vw;
  overflow: hidden;
  height: .3vw;
}

.tracks span {
  display: inline;
  height: .3vw;
  width: 20vw;
  position: absolute;
  left: 20vw;
  background: linear-gradient(to right, black 0%, black 30%, transparent 30%, transparent 39%, black 39%, black 61%, black 65%, transparent 65%, transparent 70%, black 71%, black 100%);
  animation: track 2s linear infinite;
  animation-fill-mode: forwards;
}

.tracks span:nth-child(2) {
  animation-delay: -1s;
}

.smokes:before,
.smokes:after,
.smokes span:before {
  display: block;
  content: "";
  height: .8vw;
  width: .8vw;
  background-color: #e80404;
  border-radius: 50%;
  position: absolute;
  right: .8vw;
  top: 1.5vw;
  z-index: -1;
}

.smokes:before {
  animation: smoke 1s linear infinite;
}

.smokes span:before {
  animation: smoke 1s linear infinite;
  animation-delay: -0.6s;
}

.smokes:after {
  animation: smoke 1s linear infinite;
  animation-delay: -0.3s;
}

@keyframes smoke {
  100% {
    top: -5vw;
    opacity: 0.5;
  }
}

@keyframes wheel-rotate {
  100% {
    transform: rotate(360deg);
  }
}

@keyframes track {
  100% {
    left: -20vw;
  }
}

<div class="toy-train">
  <div class="engine">
    <div class="window">
      <div class="engine-main">
        <div class="smokes">
          <span></span>
        </div>
      </div>
    </div>
    <div class="engine-body">
      <div class="wheels">
        <div class="big-wheel"></div>
        <div class="normal-wheel"></div>
      </div>
    </div>
  </div>
  <div class="locomotive">
    <div class="trash"></div>
    <div class="wheels">
      <div class="normal-wheel"></div>
      <div class="normal-wheel"></div>
    </div>
  </div>
  <div class="tracks">
    <span></span>
    <span></span>
  </div>
</div>