:root {
  --page-bg: #e6e6e6;      /* 背景（本の紙風に置き換え可） */
  --arrow-size: 40px;
  --blink-sec: 1.8s;
}

body {
  margin: 0;
  font-family: sans-serif;
  background: #f5f5f5;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

/* ビューア全体 */
.viewer {
  position: relative;
  width: 100%;
  max-width: 980px;
  height: 90vh;
  background: var(--page-bg) center/cover no-repeat;
  border-radius: 12px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.2);
  overflow: hidden;
}

/* ページ全体を横に並べて切替 */
.pages {
  display: flex;
  height: 100%;
  transition: transform 0.6s ease;
}

/* 各ページ */
.page {
  flex: 0 0 100%;
  height: 100%;
  overflow-y: auto;       /* ← ページ内は縦スクロール */
  -webkit-overflow-scrolling: touch;
  padding: clamp(16px, 3.2vw, 32px);
  box-sizing: border-box;
}

/* ページ内のカード配置（常に縦1列） */
.grid {
  display: flex;
  flex-direction: column;
  gap: clamp(12px, 2vw, 20px);
}
.card {
  width: 100%;
  background: #fff;
  border-radius: 8px;
  padding: 16px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}
.card img {
  max-width: 100%;
  border-radius: 4px;
}

/* 矢印 */
.arrow {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: var(--arrow-size);
  height: var(--arrow-size);
  background: #fff;
  border-radius: 50%;
  box-shadow: 0 2px 6px rgba(0,0,0,0.2);
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  animation: blink var(--blink-sec) infinite;
}
.arrow.left { left: 12px; }
.arrow.right { right: 12px; }

@keyframes blink {
  0%, 50%, 100% { opacity: 1; }
  25%, 75% { opacity: 0.3; }
}

/* ページ切替ラジオボタンは非表示 */
input[type=radio] { display: none; }

/* ページ切替処理 */
#p1:checked ~ .viewer .pages { transform: translateX(0%); }
#p2:checked ~ .viewer .pages { transform: translateX(-100%); }
#p3:checked ~ .viewer .pages { transform: translateX(-200%); }
#p4:checked ~ .viewer .pages { transform: translateX(-300%); }
#p5:checked ~ .viewer .pages { transform: translateX(-400%); }

/* 矢印の表示条件 */
.viewer .arrow { display: none; }
#p1:checked ~ .viewer label.next-p2 { display: flex; }
#p2:checked ~ .viewer label.prev-p1,
#p2:checked ~ .viewer label.next-p3 { display: flex; }
#p3:checked ~ .viewer label.prev-p2,
#p3:checked ~ .viewer label.next-p4 { display: flex; }
#p4:checked ~ .viewer label.prev-p3,
#p4:checked ~ .viewer label.next-p5 { display: flex; }
#p5:checked ~ .viewer label.prev-p4 { display: flex; }