【コピペOK】CSSアニメーションを使ったウェブデザイン

<div class="dynamic-bg">
  <span class="dynamic-wrap"><span class="dynamic-text">テキストと背景色の</span></span><br>
  <span class="dynamic-wrap"><span class="dynamic-text">フェードインアウト</span></span>
</div>

.dynamic-wrap {
  position: relative;
  display: inline-block;
  margin-top: 5px;
}

.dynamic-wrap::before {
  animation: dynamic-bg-animation 2.6s cubic-bezier(0.22, 1, 0.36, 1) forwards, fade-out 1s 2.6s forwards;
  background: #EBE21B;
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  transform-origin: left center;
}

.dynamic-wrap .dynamic-text {
  color: #fff;
  display: inline-block;
  font-size: 36px;
  font-weight: bold;
  padding: 5px 15px;
  position: relative;
  z-index: 1;
  opacity: 0;
  animation: text-reveal 0.5s 3s forwards;
}

@keyframes dynamic-bg-animation {
  0% {
    opacity: 0;
    transform: scaleX(0) translateX(-5%);
  }
  30% {
    transform: scaleX(1) translateX(0);
  }
  100% {
    transform: scaleX(1) translateX(0);
  }
  30%, 100% {
    opacity: 1;
  }
}

@keyframes fade-out {
  0% {
    opacity: 1;
  }
  100% {
    opacity: 0;
    transform: translateY(-100%);
  }
}

@keyframes text-reveal {
  0% {
    opacity: 0;
  }
  100% {
    opacity: 1;
  }
}