:root {
  --primary-color: #0066CC;
  --secondary-color: #004A99;
  --accent-color: #FF6600;
  --text-color: #333333;
  --bg-color: #F8F9FA;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Noto Sans JP", sans-serif;
  background: var(--bg-color);
  color: var(--text-color);
  line-height: 1.7;
}

.main-header {
  background: #fff;
  box-shadow: 0 2px 16px rgba(15, 23, 42, 0.05);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.logo-main {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--primary-color);
}

.logo-sub {
  font-size: 0.85rem;
  opacity: 0.8;
}

.nav-menu {
  list-style: none;
  display: flex;
  gap: 1rem;
}

.nav-menu a {
  color: var(--text-color);
  text-decoration: none;
  font-weight: 500;
}

main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 4rem;
}

.news-index-header {
  margin-bottom: 2rem;
}

.news-index-header h1 {
  font-size: 2.3rem;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.news-index-header p {
  color: rgba(17, 24, 39, 0.8);
}

.news-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.news-card {
  background: #fff;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
  display: flex;
  flex-direction: column;
  border: 1px solid rgba(15, 23, 42, 0.05);
}

.news-card-image {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.news-card-content {
  padding: 1rem 1.25rem 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.news-card-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--primary-color);
}

.news-card-meta {
  display: flex;
  gap: 0.5rem;
  color: rgba(15, 23, 42, 0.6);
  font-size: 0.9rem;
}

.news-card-excerpt {
  color: rgba(15, 23, 42, 0.8);
}

.news-card-link {
  margin-top: auto;
  color: var(--accent-color);
  font-weight: 600;
  text-decoration: none;
}

.news-card-link:hover {
  text-decoration: underline;
}

.news-container {
  display: grid;
  grid-template-columns: minmax(0, 3fr) minmax(280px, 1fr);
  gap: 2rem;
  margin-top: 2rem;
}

.main-content {
  background: #fff;
  padding: 2rem;
  border-radius: 16px;
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.08);
}

.article-title {
  font-size: 2rem;
  color: var(--primary-color);
  margin-bottom: 0.75rem;
}

.article-meta {
  color: rgba(15, 23, 42, 0.7);
  margin-bottom: 1.5rem;
}

.featured-image {
  width: 100%;
  height: 360px;
  object-fit: cover;
  border-radius: 12px;
  margin-bottom: 1.5rem;
}

.article-content h2 {
  font-size: 1.35rem;
  margin-bottom: 0.75rem;
}

.article-content p {
  margin-bottom: 1rem;
  color: rgba(15, 23, 42, 0.8);
}

.news-source-section {
  border-top: 1px solid rgba(15, 23, 42, 0.08);
  padding-top: 1rem;
  margin-top: 2rem;
}

.news-source-list {
  display: grid;
  gap: 0.4rem;
}

.news-source-list dt {
  font-weight: 700;
  color: rgba(15, 23, 42, 0.6);
}

.news-source-list dd {
  margin-left: 0;
  color: rgba(15, 23, 42, 0.8);
}

.sidebar {
  background: #fff;
  padding: 1.5rem;
  border-radius: 16px;
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.08);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.sidebar-section h3 {
  font-size: 1rem;
  margin-bottom: 0.5rem;
  color: var(--primary-color);
}

.sidebar-section ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.sidebar-section a {
  color: var(--accent-color);
  text-decoration: none;
}

.share-buttons {
  display: flex;
  gap: 0.5rem;
  margin-top: 1.5rem;
}

.share-btn {
  flex: 1;
  border: 1px solid rgba(15, 23, 42, 0.1);
  border-radius: 8px;
  padding: 0.6rem;
  text-align: center;
  color: var(--text-color);
  text-decoration: none;
  font-weight: 600;
}

.main-footer {
  background: #0f172a;
  color: #e2e8f0;
  padding: 2rem 1rem;
  margin-top: 3rem;
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.footer-links a {
  color: #e2e8f0;
  text-decoration: none;
}

.footer-bottom {
  max-width: 1200px;
  margin: 1.5rem auto 0;
  text-align: center;
  font-size: 0.85rem;
  color: rgba(226, 232, 240, 0.8);
}

@media (max-width: 960px) {
  .news-container {
    grid-template-columns: 1fr;
  }

  .nav-menu {
    flex-wrap: wrap;
    justify-content: center;
  }
}