动画与Codepen中的动画不同

Question

我网站上的CSS animation here缺少Codepen示例中的某些功能，例如冒烟，并且火车的某些部分之间存在间隙。使用的代码是相同的，除了在将其放入Shopify之前必须将SASS反编译为CSS。这是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>