:root {
  --text: #171717;
  --muted: #737373;
  --border: #e5e5e5;
  --bg: #ffffff;
  --bg-subtle: #fafafa;
  --accent: #2563eb;
  --serif: Georgia, 'Times New Roman', 'Hiragino Mincho ProN', serif;
  --sans: 'Hiragino Sans', 'Hiragino Kaku Gothic ProN', 'Noto Sans JP', system-ui, sans-serif;
}

* { box-sizing: border-box; }

html {
  font-size: 100%;
}

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  font-size: 1rem;
}

a { color: inherit; }

.site-header {
  border-bottom: 1px solid var(--border);
}

.site-header__inner,
.site-main,
.site-footer__inner,
.site-ad__inner {
  max-width: 72rem;
  margin: 0 auto;
  padding: 0 1rem;
}

.site-header__brand {
  display: block;
  padding: 1rem 0;
  text-decoration: none;
  flex: 1;
  min-width: 0;
}

.site-header__brand-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-header__brand-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-shrink: 0;
}

.site-nav-search {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  padding: 0.375rem 0.75rem;
  border: 1px solid #d4d4d4;
  background: #fafafa;
  color: var(--text);
  font-size: 0.875rem;
  font-weight: 500;
  text-decoration: none;
  white-space: nowrap;
}

.site-nav-search:hover {
  border-color: #737373;
  background: #fff;
}

.site-nav-search__icon {
  width: 0.875rem;
  height: 0.875rem;
  flex-shrink: 0;
}

.site-nav-hamburger {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.75rem;
  height: 2.75rem;
  border: 1px solid var(--border);
  border-radius: 0.25rem;
  cursor: pointer;
  flex-shrink: 0;
  background: var(--bg);
}

.site-nav-hamburger__icon,
.site-nav-hamburger__icon::before,
.site-nav-hamburger__icon::after {
  display: block;
  width: 1.125rem;
  height: 2px;
  background: var(--text);
  border-radius: 1px;
  position: relative;
}

.site-nav-hamburger__icon::before,
.site-nav-hamburger__icon::after {
  content: '';
  position: absolute;
  left: 0;
}

.site-nav-hamburger__icon::before { top: -6px; }
.site-nav-hamburger__icon::after { top: 6px; }

.site-nav-toggle:checked + .site-header__brand-row .site-nav-hamburger__icon {
  background: transparent;
}

.site-nav-toggle:checked + .site-header__brand-row .site-nav-hamburger__icon::before {
  top: 0;
  transform: rotate(45deg);
}

.site-nav-toggle:checked + .site-header__brand-row .site-nav-hamburger__icon::after {
  top: 0;
  transform: rotate(-45deg);
}

@media (min-width: 1024px) {
  .site-nav-hamburger { display: none; }
}

@media (min-width: 640px) {
  .site-header__brand { padding: 1.25rem 0; }
}

.site-header__title {
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(1.5rem, 4vw + 0.5rem, 1.875rem);
  font-weight: 700;
  line-height: 1.2;
}

.site-header__subtitle {
  margin: 0.25rem 0 0;
  font-size: 0.75rem;
  line-height: 1.5;
  color: var(--muted);
}

@media (min-width: 640px) {
  .site-header__subtitle { font-size: 0.875rem; }
}

/* モバイル: ハンバーガーメニュー */
.site-nav-mobile {
  display: none;
  padding-bottom: 0.75rem;
  border-top: 1px solid #f5f5f5;
}

.site-nav-toggle:checked ~ .site-nav-mobile {
  display: block;
}

.site-nav-mobile__list {
  list-style: none;
  margin: 0;
  padding: 0;
  border: 1px solid var(--border);
}

.site-nav-mobile__list a {
  display: block;
  padding: 0.625rem 0.75rem;
  font-size: 0.875rem;
  font-weight: 500;
  text-decoration: none;
  border-left: 2px solid var(--accent);
}

.site-nav-mobile__list a:hover { background: #f5f5f5; }

.site-nav--desktop {
  display: none;
  flex-wrap: wrap;
  align-items: center;
  border-top: 1px solid #f5f5f5;
  padding: 0.5rem 0;
  list-style: none;
  margin: 0;
  gap: 0.25rem;
}

@media (min-width: 1024px) {
  .site-nav-mobile { display: none !important; }
  .site-nav--desktop {
    display: flex;
  }
}

.site-nav--desktop a {
  display: block;
  padding: 0.375rem 0.75rem;
  font-size: 0.875rem;
  font-weight: 500;
  text-decoration: none;
  white-space: nowrap;
}

.site-nav--desktop a:hover { background: #f5f5f5; }

.site-ad {
  border-bottom: 1px solid #f5f5f5;
  padding: 0.5rem 0;
}

@media (min-width: 640px) {
  .site-ad { padding: 0.75rem 0; }
}

.site-ad__slot {
  border: 1px solid var(--border);
  background: var(--bg-subtle);
  min-height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--muted);
  font-size: 0.75rem;
  padding: 0.75rem;
  text-align: center;
}

@media (min-width: 640px) {
  .site-ad__slot {
    min-height: 90px;
    font-size: 0.875rem;
    padding: 1rem;
  }
}

.site-ad__slot--rectangle {
  min-height: 200px;
}

@media (min-width: 768px) {
  .site-ad__slot--rectangle { min-height: 250px; }
}

.site-ad__slot .ad-label-mobile { display: inline; }
.site-ad__slot .ad-label-desktop { display: none; }

@media (min-width: 640px) {
  .site-ad__slot .ad-label-mobile { display: none; }
  .site-ad__slot .ad-label-desktop { display: inline; }
}

.site-main {
  padding: 1.5rem 1rem 3.5rem;
}

@media (min-width: 640px) {
  .site-main { padding: 2rem 1rem 4rem; }
}

@media (min-width: 768px) {
  .site-main { padding: 2.5rem 1rem 4rem; }
}

.site-layout {
  display: grid;
  gap: 1.5rem;
}

@media (min-width: 768px) {
  .site-layout { gap: 2rem; }
}

@media (min-width: 1024px) {
  .site-layout { grid-template-columns: 1fr 280px; }
}

.site-sidebar {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.article-eyebrow {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.article-title,
.page-title {
  margin: 0.5rem 0 0;
  font-family: var(--serif);
  font-size: clamp(1.375rem, 4vw + 0.5rem, 2rem);
  line-height: 1.25;
  font-weight: 700;
}

.page-title { margin: 0; }

.article-meta {
  margin-top: 0.5rem;
  font-size: 0.75rem;
  color: var(--muted);
}

.article-header {
  border-bottom: 1px solid var(--border);
  padding-bottom: 1.25rem;
  margin-bottom: 1.5rem;
}

@media (min-width: 768px) {
  .article-header {
    padding-bottom: 1.5rem;
    margin-bottom: 2rem;
  }
}

.back-link {
  font-size: 0.875rem;
  font-weight: 500;
  text-decoration: none;
}

.back-link:hover { text-decoration: underline; }

.content-box {
  border: 1px solid var(--border);
  background: var(--bg-subtle);
  padding: 0.875rem 1rem;
  margin: 1.25rem 0;
  font-size: 1rem;
}

@media (min-width: 640px) {
  .content-box {
    padding: 1rem 1.25rem;
    margin: 1.5rem 0;
    font-size: 1rem;
  }
}

.content-box h2,
.article-section h2 {
  margin: 0 0 0.75rem;
  font-family: var(--serif);
  font-size: 1rem;
}

@media (min-width: 640px) {
  .content-box h2,
  .article-section h2 { font-size: 1.125rem; }
}

.content-box--accent {
  border-left: 4px solid var(--accent);
}

.article-section {
  margin: 1.25rem 0;
  font-size: 1rem;
}

@media (min-width: 640px) {
  .article-section {
    margin: 1.5rem 0;
    font-size: 1rem;
  }
}

.article-section h2 {
  font-size: 1.125rem;
}

@media (min-width: 640px) {
  .article-section h2 { font-size: 1.25rem; }
}

.article-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.article-list li {
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
}

@media (min-width: 640px) {
  .article-list li { padding: 1.25rem 0; }
}

.article-list a {
  text-decoration: none;
}

.article-list a:hover h2 { text-decoration: underline; }

.article-list h2 {
  margin: 0;
  font-family: var(--serif);
  font-size: 0.9375rem;
}

@media (min-width: 640px) {
  .article-list h2 { font-size: 1.0625rem; }
}

.article-list p {
  margin: 0.5rem 0 0;
  font-size: 1rem;
  color: var(--muted);
}

@media (min-width: 640px) {
  .article-list p { font-size: 1rem; }
}

.article-list .category {
  font-size: 0.75rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 2rem 0;
}

@media (min-width: 640px) {
  .site-footer { padding: 2.5rem 0; }
}

.site-footer__grid {
  display: grid;
  gap: 1.5rem;
}

@media (min-width: 640px) {
  .site-footer__grid {
    gap: 2rem;
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .site-footer__grid { grid-template-columns: repeat(4, 1fr); }
}

.site-footer h3 {
  margin: 0 0 0.75rem;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.site-footer ul {
  list-style: none;
  padding: 0;
  margin: 0;
  font-size: 0.875rem;
}

.site-footer li + li { margin-top: 0.5rem; }

.site-footer a { text-decoration: none; }
.site-footer a:hover { text-decoration: underline; }

.site-footer__bottom {
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: 0.75rem;
  color: var(--muted);
}

@media (min-width: 640px) {
  .site-footer__bottom { margin-top: 2.5rem; }
}

.sources {
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  font-size: 0.875rem;
}

@media (min-width: 640px) {
  .sources { margin-top: 2.5rem; }
}

.sources ul {
  padding-left: 1.25rem;
}