city.css

:root {
  --header-bg-color-tokyo: #00657F;
  --header-bg-color-kyoto: #AF6F5D;
  --header-bg-color-yokohama: #080623;
  --root-bg-color: #202124;
  --main-bg-color: #d1d5d7;
  --material-box-shadow: 0px 1px 3px rgba(0, 0, 0, 0.12);
}

html,
body {
  width: 100%;
  margin: 0px;
  padding: 0px;
  font-family: Segoe UI, system-ui, -apple-system, sans-serif;
  background-color: var(--main-bg-color);
  max-width: 600px;
  overflow-x: hidden;
}

html {
  background-color: var(--root-bg-color);
}

body {
  margin-left: calc(50vw - 50%);
}

.global-header {
  position: relative;
  width: 100%;
  height: 50px;
  background-color: var(--header-bg-color-tokyo);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  box-shadow: var(--material-box-shadow);

  @container style(--theme: tokyo) {
    background-color: var(--header-bg-color-tokyo);
  }

  @container style(--theme: kyoto) {
    background-color: var(--header-bg-color-kyoto);
  }

  @container style(--theme: yokohama) {
    background-color: var(--header-bg-color-yokohama);
  }
  .global-header-title {
    cursor: pointer;
  }
  .back {
    position: absolute;
    left: 20px;
    cursor: pointer;
  }
}

.header-container {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;

  .header {
    height: 200px;
    display: grid;
    grid-template-columns: 70px 1fr;
    grid-gap: 20px;

    .header-img>img {
      width: 100%;
      border-radius: 50%;
      view-transition-name: transition-trigger;
    }

    .transition-bg-to {
      width: 50px;
      height: 50px;
      border-radius: 50%;
      background-color: var(--header-bg-color-tokyo);
      position: absolute;
      z-index: -1;
      view-transition-name: transition-bg;

      @container style(--theme: tokyo) {
        background-color: var(--header-bg-color-tokyo);
      }

      @container style(--theme: kyoto) {
        background-color: var(--header-bg-color-kyoto);
      }

      @container style(--theme: yokohama) {
        background-color: var(--header-bg-color-yokohama);
      }
    }

    .header-title h1 {
      font-size: 1em;
      color: #313131;
    }
  }

  & div {
    display: flex;
    align-items: center;
    justify-content: center;
  }

}

.article-container {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;

  .article {
    width: 90%;

    & img {
      width: 100%;
      margin-top: 10px;
      margin-bottom: 10px;
    }

    & p {
      color: #2f2f2f;
    }
  }
}

::view-transition-group(transition-bg) {
  animation-duration: 0.6s;
  animation-timing-function: cubic-bezier(.09, .67, .06, 1.03);
  z-index: 97;
}

::view-transition-group(transition-trigger) {
  animation-duration: 0.5s;
  animation-timing-function: cubic-bezier(.09, .67, .06, 1.03);
  z-index: 99;
}

::view-transition-old(*),
::view-transition-new(*) {
  /* Make the height the same as the group,
  meaning the view size might not match its aspect-ratio. */
  height: 100%;
}