@charset "UTF-8";

* {
  margin: 0;
  padding: 0;
  vertical-align: bottom;
}

html{
  font-size:62.5%;
}
.waveBorder {
  background: #3498db; /* 例: 青色に変更 */
  padding: 10px;
  position: relative;
  margin-bottom: 2rem; /* ← 追加：ヘッダー下にスペース */
}
.waveBorder_title {
  color: #fff;
  text-align: center;
  font-size: 4rem;
}
.waveBorder::after {
  content: '';
  position: absolute;
  bottom: -2rem;
  left: 0;
  right: 0;
  height: 2rem;
  background:
    radial-gradient(
      circle at center 200%,
      rgba(52,152,219,0) 0%,
      rgba(52,152,219,0) 50%,
      rgba(52,152,219,1) 50%,
      rgba(52,152,219,1) 100%
    ) 0 0 / 4rem 1rem repeat-x,
    radial-gradient(
      circle at center top,
      rgba(52,152,219,1) 0%,
      rgba(52,152,219,1) 50%,
      rgba(52,152,219,0) 50%,
      rgba(52,152,219,0) 100%
    ) 2rem 0 / 4rem 2rem repeat-x;
}

body {
  display: grid;
  justify-content: center;
}

img {
  width: 100%;
  height: auto;
}

h1 {
  text-align: center;
  padding: 10px 0;
}

footer {
  text-align: center;
}

.gallery {
  max-width: 800px;
  padding: 10px;
}

ul {
  list-style: none;
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  padding-top: 10px;
  gap: 10px;
}

ul li img {
  transition: opacity .5s;
}

ul li img:hover {
  cursor: pointer;
  opacity: .7;
}

.gallery div {
  position: relative;
}

#caption {
  position: absolute;
  bottom: 0;
  background: rgba(0, 0, 0, .5);
  padding: 10px;
  width: 100%;
  box-sizing: border-box;
  color: #FFF;
}

@media screen and (max-width: 640px) {
  ul {
    grid-template-columns: 1fr 1fr;
  }
}