:root {
  --ink: #172a32;
  --muted: #52666f;
  --brand: #087f78;
  --brand-dark: #05615d;
  --brand-pale: #e8f6f4;
  --accent: #e86f51;
  --line: #d9e5e7;
  --surface: #fff;
  --soft: #f4f8f8;
  --shadow: 0 14px 40px rgba(18, 54, 65, .10);
  --radius: 18px;
}
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 86px; }
body {
  margin: 0;
  color: var(--ink);
  background: #f8fbfb;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN", "Yu Gothic", Meiryo, sans-serif;
  font-size: 16px;
  line-height: 1.9;
  overflow-wrap: anywhere;
  -webkit-text-size-adjust: 100%;
}
img { display: block; max-width: 100%; height: auto; border: 0; }
a { color: var(--brand-dark); text-underline-offset: .18em; }
a:hover { color: var(--accent); }
p, ul, ol { margin-top: 0; }
strong { color: #143f46; }
.skip-link { position: fixed; top: 8px; left: 8px; z-index: 100; padding: 8px 14px; border-radius: 8px; color: #fff; background: var(--brand-dark); transform: translateY(-150%); }
.skip-link:focus { transform: translateY(0); }
.site-header { position: sticky; top: 0; z-index: 20; border-bottom: 1px solid rgba(217,229,231,.9); background: rgba(255,255,255,.94); backdrop-filter: blur(12px); }
.site-header__inner { display: flex; align-items: center; justify-content: space-between; gap: 20px; width: min(1160px, calc(100% - 32px)); min-height: 68px; margin: 0 auto; }
.site-brand { color: var(--ink); font-size: clamp(.92rem,2vw,1.05rem); font-weight: 800; line-height: 1.35; text-decoration: none; }
.site-header__cta, .button, .sidebar__cta { display: inline-flex; align-items: center; justify-content: center; min-height: 46px; padding: 10px 20px; border-radius: 999px; color: #fff; background: var(--brand); font-weight: 800; line-height: 1.35; text-decoration: none; box-shadow: 0 8px 20px rgba(8,127,120,.20); }
.site-header__cta:hover, .button:hover, .sidebar__cta:hover { color: #fff; background: var(--brand-dark); }
.hero { display: grid; grid-template-columns: minmax(0,1.12fr) minmax(360px,.88fr); width: min(1240px,calc(100% - 40px)); min-height: 480px; margin: 32px auto 54px; overflow: hidden; border-radius: 26px; background: #e5f2f0; box-shadow: var(--shadow); }
.hero__media { min-height: 380px; }
.hero__media img { width: 100%; height: 100%; object-fit: cover; }
.hero__content { display: flex; flex-direction: column; justify-content: center; padding: clamp(34px,4vw,54px); background: linear-gradient(145deg,#effaf8,#dcedea); }
.eyebrow { margin-bottom: 10px; color: var(--brand-dark); font-size: .83rem; font-weight: 800; letter-spacing: .12em; text-transform: uppercase; }
h1 { margin: 0 0 22px; font-size: clamp(2rem,3.2vw,2.55rem); line-height: 1.34; letter-spacing: .01em; }
.hero__lead { margin-bottom: 28px; color: var(--muted); font-size: 1.05rem; }
.hero .button { align-self: flex-start; }
.page-layout { display: grid; grid-template-columns: minmax(0,800px) 280px; align-items: start; gap: 48px; width: min(1160px,calc(100% - 40px)); margin: 0 auto 80px; }
.article { min-width: 0; }
.toc { margin-bottom: 46px; padding: clamp(22px,4vw,34px); border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); box-shadow: 0 8px 26px rgba(18,54,65,.06); }
.toc__title { margin-bottom: 12px; font-size: 1.1rem; font-weight: 800; }
.toc ol { margin-bottom: 0; padding-left: 1.4em; columns: 2; column-gap: 36px; }
.toc li { break-inside: avoid; margin-bottom: 6px; }
.toc a { color: var(--ink); text-decoration-color: #b7cdcf; }
.content-section { margin-bottom: 58px; padding: clamp(24px,5vw,46px); border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); box-shadow: 0 8px 30px rgba(18,54,65,.055); }
.content-section h2 { position: relative; margin: 0 0 30px; padding-bottom: 16px; font-size: clamp(1.5rem,3vw,2.05rem); line-height: 1.45; letter-spacing: .01em; }
.content-section h2::after { position: absolute; bottom: 0; left: 0; width: 64px; height: 4px; border-radius: 4px; background: var(--brand); content: ""; }
.content-section p:last-child { margin-bottom: 0; }
.article-image { margin: 0 0 30px; overflow: hidden; border-radius: 14px; background: var(--soft); }
.article-image img { width: 100%; aspect-ratio: 960 / 524; object-fit: cover; }
.check-list { display: grid; gap: 12px; margin: 28px 0 0; padding: 0; list-style: none; }
.check-list li { position: relative; padding: 14px 16px 14px 48px; border-radius: 12px; background: var(--soft); }
.check-list li::before { position: absolute; top: 14px; left: 16px; display: grid; width: 24px; height: 24px; place-items: center; border-radius: 50%; color: #fff; background: var(--brand); font-weight: 800; line-height: 1; content: "✓"; }
.steps { display: grid; gap: 14px; margin: 26px 0 0; padding: 0; list-style: none; }
.steps li { display: grid; grid-template-columns: 44px 1fr; gap: 14px; align-items: start; }
.steps li > span { display: grid; width: 42px; height: 42px; place-items: center; border-radius: 50%; color: #fff; background: var(--brand); font-weight: 800; }
.steps strong { display: block; padding-top: 4px; font-size: 1.05rem; }
.steps p { margin: 2px 0 0; color: var(--muted); }
.faq-list { display: grid; gap: 12px; }
.faq-list details { border: 1px solid var(--line); border-radius: 12px; background: #fff; }
.faq-list summary { position: relative; padding: 18px 48px 18px 20px; cursor: pointer; font-weight: 800; list-style: none; }
.faq-list summary::-webkit-details-marker { display: none; }
.faq-list summary::after { position: absolute; top: 16px; right: 20px; color: var(--brand); font-size: 1.35rem; content: "+"; }
.faq-list details[open] summary::after { content: "−"; }
.faq-list details p { margin: 0; padding: 0 20px 20px; color: var(--muted); }
.recommended { padding-right: clamp(18px,3vw,34px); padding-left: clamp(18px,3vw,34px); }
.section-heading { text-align: center; }
.section-heading h2::after { left: 50%; transform: translateX(-50%); }
.ad-notice { margin: 0 auto 24px; padding: 12px 16px; border-radius: 10px; color: #6d4c41; background: #fff4e9; font-size: .9rem; text-align: center; }
.ad-grid { display: grid; gap: 20px; }
.ad-card { position: relative; padding: clamp(20px,4vw,30px); overflow: hidden; border: 1px solid var(--line); border-radius: 16px; background: linear-gradient(180deg,#fff,#f7fbfb); }
.ad-card__label { display: inline-flex; margin-bottom: 10px; padding: 3px 10px; border-radius: 999px; color: #764631; background: #fff0e6; font-size: .75rem; font-weight: 800; }
.ad-card h3 { margin: 0 0 8px; font-size: 1.42rem; line-height: 1.4; }
.ad-card__lead { color: var(--brand-dark); font-weight: 700; }
.ad-card ul { margin-bottom: 24px; padding-left: 1.3em; }
.ad-card__creative { display: grid; min-height: 252px; place-items: center; overflow: hidden; }
.ad-card__creative > a { display: block; max-width: 300px; }
.ad-card__creative img:not([width="1"]) { width: min(300px,100%); height: auto; }
.ad-card__creative > img[width="1"], .ad-card__text-link img[width="1"] { position: absolute; width: 1px; height: 1px; }
.ad-card__text-link { margin: 18px auto 0; text-align: center; }
.ad-card__text-link a { font-weight: 800; }
.summary { border-color: #bddbd7; background: var(--brand-pale); }
.sidebar { position: sticky; top: 96px; }
.sidebar__card { display: grid; gap: 8px; padding: 24px; border: 1px solid var(--line); border-radius: var(--radius); background: #fff; box-shadow: 0 8px 28px rgba(18,54,65,.06); }
.sidebar__title { margin-bottom: 8px; font-weight: 800; }
.sidebar__card > a:not(.sidebar__cta) { padding: 8px 0; border-bottom: 1px solid #edf2f3; color: var(--ink); text-decoration: none; }
.sidebar__cta { margin-top: 12px; text-align: center; }
.site-footer { color: #e9f4f4; background: #173a42; }
.site-footer__inner { width: min(960px,calc(100% - 40px)); margin: 0 auto; padding: 40px 0; text-align: center; }
.site-footer p { margin-bottom: 12px; }
.site-footer small { color: #b9cdcf; }
.page-top { position: fixed; right: 18px; bottom: 18px; display: grid; width: 44px; height: 44px; place-items: center; border-radius: 50%; color: #fff; background: var(--brand); font-size: 1.15rem; font-weight: 800; text-decoration: none; box-shadow: 0 8px 22px rgba(8,127,120,.25); }
@media (max-width: 960px) {
  .hero { grid-template-columns: 1fr; }
  .hero__media { min-height: 360px; max-height: 520px; }
  .page-layout { grid-template-columns: minmax(0,1fr); width: min(800px,calc(100% - 32px)); }
  .sidebar { display: none; }
}
@media (max-width: 640px) {
  body { font-size: 15.5px; line-height: 1.82; }
  .site-header__inner { width: min(100% - 24px,1160px); min-height: 62px; }
  .site-header__cta { min-height: 40px; padding: 8px 12px; font-size: .78rem; }
  .hero { width: calc(100% - 24px); min-height: 0; margin: 16px auto 34px; border-radius: 18px; }
  .hero__media { min-height: 0; aspect-ratio: 3 / 2; }
  .hero__content { padding: 26px 22px 30px; }
  h1 { font-size: clamp(1.7rem,8vw,2.25rem); }
  .hero__lead { font-size: .98rem; }
  .page-layout { width: calc(100% - 24px); margin-bottom: 50px; }
  .toc { margin-bottom: 30px; padding: 20px; }
  .toc ol { columns: 1; }
  .content-section { margin-bottom: 28px; padding: 24px 20px; border-radius: 15px; }
  .content-section h2 { margin-bottom: 24px; font-size: 1.42rem; }
  .check-list li { padding-left: 44px; }
  .recommended { padding-right: 14px; padding-left: 14px; }
  .ad-card { padding: 20px 14px; }
  .ad-card__creative { min-height: 0; }
  .page-top { right: 12px; bottom: 12px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}