body {
  font-family: Meiryo, sans-serif;
  color: #444444;
  margin: 0;
  padding: 0;
  padding-top: 70px;
}
header {
  background-color: white;
  position: fixed;
  width: 100%;
  top: 0;
  z-index: 1000;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}
header img {
  height: 35px;
  width: auto;
}
.logo {
  display: block;
  max-width: 150px;
}
.logo img {
  max-height: 35px;
  width: auto;
}
#footer {
  background-color: #f0f0f0;
  text-align: center;
  padding: 10px 0;
}
.back-to-top {
  position: fixed;
  bottom: 20px;
  right: 20px;
  background-color: #9acd32;
  color: white;
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
  transition: background-color 0.3s;
}
.back-to-top:hover {
  background-color: #7fbf00;
}
.common-wrap {
  position: relative;
  overflow: hidden;
  margin-bottom: 30px;
  border-radius: 6px;
}

.common-wrap img {
  width: 100%;
  height: auto;
  aspect-ratio: 4/3;
  background-color: white;
  object-fit: cover;
}

.common-wrap img:not([src]), 
.common-wrap img[src=""] {
  background-color: #f0f0f0; /* 薄いグレー */
  border: 1px solid #ddd;
  width: 100%;
  height: 0;
  padding-bottom: 75%; /* 4:3 aspect ratio */
}

.common-wrap:hover img {
  transform: scale(1.1);
}

blockquote {
  position: relative;
  padding: 15px 15px 8px 15px;
  box-sizing: border-box;
  font-style: italic;
  background: #efefef;
  color: #555;
}
blockquote p {
  padding: 0;
  margin: 10px 0;
  line-height: 1.7;
}

blockquote cite {
  display: block;
  text-align: right;
  color: #888888;
  font-size: 0.9em;
}

/* Title box for year pages */
.wt-title-box {
  background: skyblue;
  width: 100%;
  padding: 10px 0;
  margin: 20px 0 5px 0;
  border-radius: 10px;
}
.wt-title-box h4 {
  text-align: center;
  margin: 0;
}
.youtubetitle {
  text-align: center; 
  font-size: 0.8em; 
  margin-bottom: 0;
}
.btnmove {
  padding-top: 40px;
  padding-bottom: 80px;
  text-align: center;
}
.btn {
  padding: 10px 30px;
  color: black;
  display: inline-block;
  opacity: 0.8;
  border-radius: 3px;
  text-decoration: none;
  box-shadow: 0 5px blue;
}
.btn:active {
  position: relative;
  top: 5px;
  box-shadow: none;
}
.back {
  background-color: skyblue;
  margin-right: 100px;
}
.next {
  background-color: skyblue;
}