*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --bg: #ffffff;
  --fg: #1a1a1a;
  --accent: #999999;
  --content-max: 520px;
}

html {
  scroll-behavior: smooth;
  -webkit-tap-highlight-color: transparent;
}

body {
  background: var(--bg);
  color: var(--fg);
  font-family: "Georgia", "Times New Roman", serif;
  overflow-x: hidden;
  min-height: 100dvh;
}

/* ─── Progress bar ─── */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  background: #1a1a1a;
  z-index: 200;
  transition: width 0.1s ease;
}

/* ─── Image Strip ─── */
.strip {
  padding-top: 0;
  padding-bottom: 40px;
}

.strip-inner {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0;
}

.slide {
  width: 100%;
  display: block;
  scroll-margin-top: 56px;
}

.slide img {
  width: 100%;
  height: auto;
  display: block;
  -webkit-user-drag: none;
  user-select: none;
}

/* ─── インデックスページ ─── */

/* 上部：画像の上36%（ピンクINDEXエリア）だけ見せる */
.index-top {
  width: 100%;
  /* 366×741px の上36% = 366×267px 相当のアスペクト比 */
  aspect-ratio: 366 / 260;
  overflow: hidden;
}

.index-top img {
  width: 100%;
  height: auto;
  display: block;
  -webkit-user-drag: none;
  user-select: none;
}

/* リストエリア */
:root {
  --navy: #1a3a8e;
}

.index-list {
  background: #fff;
  padding: 18px 16%;
  font-family:
    "Hiragino Kaku Gothic ProN", "Hiragino Kaku Gothic Pro", "Noto Sans JP",
    "Yu Gothic", "メイリオ", sans-serif;
}

.index-section-header {
  background: var(--navy);
  color: #fff;
  font-size: 17px;
  font-weight: 800;
  padding: 12px 16px;
  letter-spacing: 0.08em;
  margin-bottom: 0;
}

/* OTHER ヘッダーの上には少しスペースを */
.index-section-header + .index-row,
.index-row + .index-section-header {
  /* セクションヘッダー直前/直後の境界を整える */
}
.index-section-header:not(:first-child) {
  margin-top: 22px;
}

.index-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 6px;
  border-bottom: 1.5px solid #1a1a1a;
  text-decoration: none;
  color: var(--navy);
  background: #fff;
  -webkit-tap-highlight-color: rgba(26, 58, 142, 0.08);
}

.index-row:active {
  background: #f0f4ff;
}

.index-row-label {
  font-size: 16px;
  font-weight: 800;
  color: var(--navy);
  flex: 1;
  padding-right: 8px;
  letter-spacing: 0.02em;
}

.index-row-num {
  font-size: 22px;
  font-weight: 900;
  color: var(--navy);
  white-space: nowrap;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-family: "Arial Black", "Helvetica Neue", sans-serif;
  line-height: 1;
}

.index-arrow {
  font-size: 16px;
  color: var(--navy);
  margin-left: 2px;
  line-height: 1;
}

/* ─── PC向け ─── */
@media (min-width: 600px) {
  body {
    background: #ffffff;
  }

  .strip-inner {
    padding: 0;
    box-shadow: 0 0 40px rgba(0, 0, 0, 0.12);
  }
}