<div><h1>江戸を東京と改称する構想は、江戸時代後期の経世家である佐藤信淵が文政6年(1823年)に著した『混同秘策』にすでに現れていた。</h1></div>
body {
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  height: 100%;
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  background: #282828;
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div {

  width: 20%;
  height: auto;
  margin: auto;
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margin-top:20px;
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  animation: morphing 10s infinite;
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div:hover {
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div h1 {
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}

@keyframes morphing {
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  25% {
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  75% {
    border-radius: 33% 67% 58% 42%/63% 68% 32% 37%;
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}

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