:root {
  --bg: #fefefe;
  --text: #1a1a1a;
  --text-sub: #6f6f6f;
  --border: #dddddd;
  --soft: #f7faf9;
  --soft-2: #f2f4f3;
  --accent: #1f6f5b;
  --accent-soft: #e7f1ed;
  --shadow: 0 12px 30px rgba(0, 0, 0, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic", Meiryo, sans-serif;
  text-size-adjust: 100%;
}

body {
  margin: 0;
  font-size: 17px;
  line-height: 1.9;
  letter-spacing: 0;
}

a {
  color: inherit;
}

.site-header {
  border-bottom: 1px solid var(--border);
  background: rgba(254, 254, 254, 0.94);
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  max-width: 680px;
  margin: 0 auto;
  padding: 16px 18px;
  text-decoration: none;
}

.brand-mark {
  display: block;
  width: 34px;
  height: 34px;
  flex: 0 0 34px;
  border-radius: 50%;
  object-fit: cover;
}

.brand strong,
.brand small {
  display: block;
}

.brand small {
  color: var(--text-sub);
  font-size: 12px;
  line-height: 1.4;
}

.page-shell {
  max-width: 680px;
  margin: 0 auto;
  padding: 20px 18px 64px;
}

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  color: var(--text-sub);
  font-size: 13px;
  margin: 8px 0 34px;
}

.breadcrumbs a {
  text-decoration: none;
}

.hero {
  padding: 18px 0 22px;
}

.eyebrow {
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0;
  margin: 0 0 8px;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1 {
  font-size: clamp(30px, 7vw, 44px);
  line-height: 1.28;
  margin: 0 0 18px;
}

h2 {
  font-size: 22px;
  line-height: 1.45;
  margin: 42px 0 12px;
}

h3 {
  font-size: 17px;
  line-height: 1.5;
  margin: 0 0 6px;
}

.lead {
  color: #333;
  font-size: 19px;
  line-height: 1.85;
}

.section {
  margin: 36px 0;
}

.link-grid {
  display: grid;
  gap: 12px;
  margin: 24px 0 46px;
}

.link-card {
  display: block;
  padding: 18px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--soft);
  text-decoration: none;
}

.link-card span {
  display: block;
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
}

.link-card strong {
  display: block;
  font-size: 18px;
  line-height: 1.5;
  margin-top: 4px;
}

.article {
  padding-bottom: 20px;
}

.key-points {
  margin: 42px 0;
  padding: 18px 20px;
  border-left: 4px solid var(--accent);
  background: var(--soft);
}

.key-points h2 {
  margin-top: 0;
}

.key-points ul {
  margin: 0;
  padding-left: 22px;
}

.closing {
  color: #333;
  font-weight: 600;
}

.article-ad {
  display: flex;
  justify-content: center;
  margin: 52px 0 42px;
  padding: 22px 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.article-ad .adsbygoogle {
  display: inline-block;
  width: 320px;
  height: 50px;
}

@media (min-width: 500px) {
  .article-ad .adsbygoogle {
    width: 468px;
    height: 60px;
  }
}

@media (min-width: 800px) {
  .article-ad .adsbygoogle {
    width: 728px;
    height: 90px;
  }
}

.video-list {
  display: grid;
  gap: 24px;
}

.card-list {
  display: grid;
  gap: 12px;
}

.content-card {
  display: block;
  padding: 16px 18px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
  text-decoration: none;
}

.content-card span {
  color: var(--accent);
  display: block;
  font-size: 12px;
  font-weight: 700;
  margin-bottom: 4px;
}

.content-card strong {
  display: block;
  font-size: 17px;
  line-height: 1.5;
}

.content-card p {
  color: var(--text-sub);
  font-size: 14px;
  line-height: 1.7;
  margin: 8px 0 0;
}

.video-row {
  display: grid;
  gap: 12px;
  padding-bottom: 22px;
  border-bottom: 1px solid var(--border);
}

.video-row p {
  margin: 0;
  color: var(--text-sub);
  font-size: 14px;
}

.qa-list {
  display: grid;
  gap: 22px;
  margin-top: 32px;
}

.qa-item {
  padding: 18px 0;
  border-top: 1px solid var(--border);
}

.qa-item h2 {
  margin: 0 0 12px;
  font-size: 20px;
}

.qa-item h3 {
  margin-bottom: 10px;
  font-size: 18px;
}

.book-link {
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--soft);
}

.archive-note {
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--soft);
  color: #333;
  font-size: 15px;
}

.archive-date {
  color: var(--text-sub);
  font-size: 14px;
}

.archive-table-wrap {
  width: 100%;
  margin: 30px 0;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
}

.archive-table {
  width: 100%;
  min-width: 640px;
  border-collapse: collapse;
  font-size: 14px;
  line-height: 1.65;
}

.archive-table-wide {
  min-width: 960px;
}

.archive-table th,
.archive-table td {
  padding: 10px 12px;
  border-right: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  text-align: left;
  vertical-align: top;
}

.archive-table th:last-child,
.archive-table td:last-child {
  border-right: 0;
}

.archive-table tr:last-child td {
  border-bottom: 0;
}

.archive-table thead th {
  background: var(--soft);
  font-weight: 700;
  white-space: nowrap;
}

.archive-table th:first-child,
.archive-table td:first-child,
.archive-table th:nth-child(3),
.archive-table td:nth-child(3) {
  text-align: center;
  white-space: nowrap;
}

.archive-list {
  margin-top: 30px;
}

.bot-exit {
  margin: 56px 0 6px;
  padding: 22px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--accent-soft);
}

.bot-exit h2 {
  margin-top: 0;
}

.button-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  margin-top: 8px;
  padding: 0 18px;
  border-radius: 999px;
  background: var(--accent);
  color: #fff;
  font-weight: 700;
  text-decoration: none;
}

.site-footer {
  max-width: 680px;
  margin: 0 auto;
  padding: 28px 18px 54px;
  border-top: 1px solid var(--border);
  color: var(--text-sub);
  font-size: 13px;
}

lite-youtube {
  position: relative;
  display: block;
  aspect-ratio: 16 / 9;
  width: 100%;
  overflow: hidden;
  border: 0;
  border-radius: 8px;
  background: #111 center / cover no-repeat;
  box-shadow: var(--shadow);
}

lite-youtube::before {
  position: absolute;
  inset: 0;
  content: "";
  background: linear-gradient(180deg, rgba(0,0,0,0.05), rgba(0,0,0,0.3));
}

lite-youtube button {
  position: absolute;
  inset: 0;
  display: grid;
  width: 100%;
  height: 100%;
  place-items: center;
  border: 0;
  background: transparent;
  cursor: pointer;
}

lite-youtube button::before {
  content: "";
  width: 68px;
  height: 48px;
  border-radius: 14px;
  background: rgba(31, 111, 91, 0.94);
  box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

lite-youtube button::after {
  position: absolute;
  content: "";
  margin-left: 5px;
  border-left: 17px solid #fff;
  border-top: 11px solid transparent;
  border-bottom: 11px solid transparent;
}

lite-youtube iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

@media (min-width: 720px) {
  .page-shell {
    padding-top: 34px;
  }

  .video-row {
    grid-template-columns: 220px 1fr;
    align-items: center;
  }
}