:root {
  --bg: #f8fbfb;
  --surface: #ffffff;
  --surface-soft: #eef7f5;
  --text: #263233;
  --muted: #647273;
  --line: #d9e7e4;
  --accent: #3f8f86;
  --accent-dark: #236c64;
  --rose: #c9828d;
  --ink: #1f3c3f;
  --shadow: 0 18px 42px rgba(31, 60, 63, 0.10);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Kaku Gothic ProN", "Yu Gothic", Meiryo, sans-serif;
  line-height: 1.85;
}

a {
  color: var(--accent-dark);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.site-header {
  background: rgba(255, 255, 255, 0.96);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 10;
}

.header-inner,
.hero-inner,
.main-layout,
.footer-inner {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 14px 0;
}

.brand {
  color: var(--ink);
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: 210px;
}

.brand:hover {
  text-decoration: none;
}

.brand-mark {
  align-items: center;
  background: var(--accent);
  border-radius: 8px;
  color: #fff;
  display: inline-flex;
  font-weight: 700;
  height: 36px;
  justify-content: center;
  width: 36px;
}

.brand strong {
  display: block;
  font-size: 18px;
  line-height: 1.2;
}

.brand small {
  color: var(--muted);
  display: block;
  font-size: 12px;
  line-height: 1.4;
}

.site-nav,
.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 14px;
}

.site-nav {
  justify-content: flex-end;
  font-size: 14px;
}

.site-nav a {
  color: var(--muted);
}

.site-nav a[aria-current="page"],
.footer-links a[aria-current="page"] {
  color: var(--accent-dark);
  font-weight: 700;
}

.hero {
  background:
    linear-gradient(135deg, rgba(63, 143, 134, 0.12), rgba(201, 130, 141, 0.10)),
    #ffffff;
  border-bottom: 1px solid var(--line);
}

.hero-inner {
  padding: 64px 0 54px;
}

.eyebrow {
  color: var(--accent-dark);
  font-size: 14px;
  font-weight: 700;
  margin: 0 0 10px;
}

h1,
h2,
h3,
p {
  letter-spacing: 0;
}

h1 {
  font-size: clamp(32px, 6vw, 50px);
  line-height: 1.25;
  margin: 0 0 18px;
}

h2 {
  font-size: 24px;
  line-height: 1.45;
  margin: 0 0 14px;
}

h3 {
  font-size: 18px;
  line-height: 1.55;
  margin: 0 0 8px;
}

p {
  margin: 0 0 16px;
}

.lead {
  color: var(--muted);
  font-size: 18px;
  max-width: 820px;
}

.main-layout {
  align-items: start;
  display: grid;
  gap: 28px;
  grid-template-columns: minmax(0, 1fr) 300px;
  padding: 42px 0 54px;
}

.article,
.side-note,
.topic-card,
.cta-panel {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.article {
  padding: 32px;
}

.content-section {
  border-bottom: 1px solid var(--line);
  margin-bottom: 28px;
  padding-bottom: 26px;
}

.content-section:last-child {
  border-bottom: 0;
  margin-bottom: 0;
  padding-bottom: 0;
}

.topic-grid {
  display: grid;
  gap: 14px;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.topic-card {
  color: var(--text);
  display: block;
  padding: 18px;
}

.topic-card:hover {
  border-color: var(--accent);
  text-decoration: none;
}

.topic-card p {
  color: var(--muted);
  font-size: 14px;
  margin-bottom: 0;
}

.side-note {
  padding: 22px;
  position: sticky;
  top: 86px;
}

.side-note h2 {
  font-size: 18px;
}

.side-note ul {
  margin: 0 0 16px;
  padding-left: 1.2em;
}

.side-note li {
  color: var(--muted);
  margin: 0 0 8px;
}

.text-link {
  font-weight: 700;
}

.cta-panel {
  background: var(--surface-soft);
  margin-top: 30px;
  padding: 26px;
}

.button {
  align-items: center;
  background: var(--accent);
  border-radius: 8px;
  color: #fff;
  display: inline-flex;
  font-weight: 700;
  justify-content: center;
  min-height: 46px;
  padding: 10px 18px;
}

.button:hover {
  background: var(--accent-dark);
  text-decoration: none;
}

.site-footer {
  background: var(--ink);
  color: #eaf3f1;
  padding: 34px 0;
}

.site-footer p {
  color: #c7d6d4;
  max-width: 760px;
}

.site-footer a {
  color: #fff;
}

.footer-links {
  margin: 14px 0;
}

.copyright {
  font-size: 13px;
  margin-bottom: 0;
}

@media (max-width: 860px) {
  .header-inner {
    align-items: flex-start;
    flex-direction: column;
  }

  .site-nav {
    justify-content: flex-start;
  }

  .hero-inner {
    padding: 46px 0 40px;
  }

  .main-layout {
    grid-template-columns: 1fr;
    padding: 30px 0 42px;
  }

  .article {
    padding: 22px;
  }

  .topic-grid {
    grid-template-columns: 1fr;
  }

  .side-note {
    position: static;
  }
}