body {
  margin: 0;
  font-family: "Yu Gothic", "Meiryo", "Hiragino Kaku Gothic ProN", sans-serif;
  line-height: 1.8;
  color: #222;
  background: #f5f7fa;
}

.site-header {
  background: #1f3a5f;
  color: #ffffff;
  padding: 32px 24px;
}

.header-inner {
  max-width: 1080px;
  margin: 0 auto;
}

.site-header h1 {
  margin: 0;
  font-size: 32px;
  letter-spacing: 0.03em;
}

.site-header p {
  margin: 8px 0 0;
  font-size: 16px;
  color: #e6edf5;
}

.site-nav {
  background: #ffffff;
  border-bottom: 1px solid #d9dee7;
  padding: 12px 24px;
  text-align: center;
  position: sticky;
  top: 0;
}

.site-nav a {
  display: inline-block;
  margin: 4px 12px;
  color: #1f3a5f;
  text-decoration: none;
  font-weight: bold;
}

.site-nav a:hover {
  text-decoration: underline;
}

.container {
  max-width: 1080px;
  margin: 32px auto;
  padding: 0 24px;
}

.hero {
  background: #ffffff;
  padding: 36px;
  border-radius: 16px;
  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.06);
}

section {
  background: #ffffff;
  margin-bottom: 24px;
  padding: 28px 32px;
  border-radius: 16px;
  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.05);
}

h2 {
  color: #1f3a5f;
  border-left: 6px solid #1f3a5f;
  padding-left: 12px;
  margin-top: 0;
}

h3 {
  color: #1f3a5f;
  margin-top: 0;
}

ul {
  padding-left: 1.4em;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
}

.card {
  border: 1px solid #d9dee7;
  border-radius: 14px;
  padding: 20px;
  background: #fbfcfe;
}

.card p {
  font-size: 15px;
}

.card a {
  color: #1f3a5f;
  font-weight: bold;
  text-decoration: none;
}

.card a:hover {
  text-decoration: underline;
}

.news-list {
  list-style: none;
  padding-left: 0;
}

.news-list li {
  border-bottom: 1px solid #e1e5ec;
  padding: 10px 0;
}

.news-list span {
  display: inline-block;
  min-width: 70px;
  color: #1f3a5f;
  font-weight: bold;
}

.site-footer {
  text-align: center;
  padding: 28px 16px;
  background: #e9edf3;
  color: #555;
  font-size: 14px;
}

@media screen and (max-width: 800px) {
  .site-header h1 {
    font-size: 24px;
  }

  .site-nav {
    text-align: left;
  }

  .site-nav a {
    display: block;
    margin: 6px 0;
  }

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

  section,
  .hero {
    padding: 24px;
  }
}
.note {
  color: #666;
  font-size: 14px;
}
.publication-list {
  padding-left: 1.4em;
}

.publication-list li {
  margin-bottom: 18px;
}

.publication-list a {
  display: inline-block;
  margin-right: 10px;
  font-weight: bold;
}

.research-card {
  overflow: hidden;
}

.research-content {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 28px;
  align-items: center;
}

.research-image img {
  max-width: 180px;
  width: 100%;
  height: auto;
  display: block;
  margin: 0 auto;
  border-radius: 10px;
  border: 1px solid #d9dee7;
  background: #ffffff;
}

.research-text p {
  margin-top: 0;
}

.button-link {
  display: inline-block;
  padding: 0.55em 1.1em;
  margin: 0.3em 0.2em;
  background-color: #2f6f73;
  color: #ffffff;
  text-decoration: none;
  border-radius: 6px;
  font-weight: 600;
  line-height: 1.4;
}

.button-link:hover {
  background-color: #24585b;
  color: #ffffff;
  text-decoration: none;
}

@media screen and (max-width: 800px) {
  .research-content {
    grid-template-columns: 1fr;
  }
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.topic-card {
  border: 1px solid #d9dee7;
  border-radius: 16px;
  padding: 22px;
  background: #fbfcfe;
}

.topic-card h3 {
  color: #1f3a5f;
  margin-top: 14px;
}

.topic-card p {
  font-size: 15px;
}

.topic-image {
  text-align: center;
}

.topic-image img {
  max-width: 220px;
  width: 100%;
  height: auto;
  display: inline-block;
  border-radius: 10px;
  border: 1px solid #d9dee7;
  background: #ffffff;
}

@media screen and (max-width: 800px) {
  .topic-grid {
    grid-template-columns: 1fr;
  }
}

.paper-list {
  padding-left: 1.4em;
}

.paper-list li {
  margin-bottom: 10px;
  line-height: 1.7;
}

.research-text h4 {
  color: #1f3a5f;
  margin-top: 22px;
  margin-bottom: 8px;
}

.empty-image {
  min-height: 1px;
}

.no-image-content {
  grid-template-columns: 160px 1fr;
}

.publication-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.publication-card {
  border: 1px solid #d9dee7;
  border-radius: 16px;
  padding: 22px;
  background: #fbfcfe;
}

.publication-card h3 {
  color: #1f3a5f;
  margin-top: 14px;
  margin-bottom: 8px;
}

.publication-card p {
  font-size: 15px;
}

.publication-image {
  text-align: center;
}

.publication-image img {
  max-width: 260px;
  width: 100%;
  height: auto;
  display: inline-block;
  border-radius: 10px;
  border: 1px solid #d9dee7;
  background: #ffffff;
}

@media screen and (max-width: 800px) {
  .publication-grid {
    grid-template-columns: 1fr;
  }
}

.publication-list {
  padding-left: 1.4em;
}

.publication-list li {
  margin-bottom: 12px;
  line-height: 1.7;
}

/* Mobile dropdown navigation */

.mobile-nav {
  display: none;
}

.desktop-nav {
  display: flex;
}

/* Smartphone only */
@media screen and (max-width: 700px) {
  .desktop-nav {
    display: none !important;
  }

  .mobile-nav {
    display: block !important;
    background-color: #1f3a5f;
    padding: 8px 16px;
  }

  .mobile-nav details {
    color: #ffffff;
  }

  .mobile-nav summary {
    cursor: pointer;
    font-weight: bold;
    padding: 10px 0;
    color: #ffffff;
    list-style: none;
  }

  .mobile-nav summary::-webkit-details-marker {
    display: none;
  }

  .mobile-nav summary::after {
    content: " ▼";
    font-size: 0.9em;
  }

  .mobile-nav details[open] summary::after {
    content: " ▲";
  }

  .mobile-nav a {
    display: block;
    color: #ffffff;
    text-decoration: none;
    padding: 10px 0;
    border-top: 1px solid rgba(255, 255, 255, 0.25);
  }

  .mobile-nav a:hover {
    background-color: rgba(255, 255, 255, 0.12);
  }
}

/* Final navigation control */
/* PC: show normal horizontal menu only */
.mobile-nav {
  display: none !important;
}

.desktop-nav {
  display: flex !important;
}

/* Smartphone: show dropdown menu only */
@media screen and (max-width: 700px) {
  .desktop-nav {
    display: none !important;
  }

  .mobile-nav {
    display: block !important;
  }
}

/* Mobile adjustment for research content pages */
@media screen and (max-width: 768px) {
  .container {
    padding-left: 16px;
    padding-right: 16px;
  }

  .container section {
    margin-left: 0;
    margin-right: 0;
  }

  .container p,
  .container li {
    max-width: none;
    margin-left: 0;
    margin-right: 0;
    text-align: left;
  }

  .container ol,
  .container ul {
    padding-left: 1.2em;
  }
}
/* Mobile layout adjustment for research pages without images */
@media screen and (max-width: 768px) {
  .container {
    padding-left: 16px;
    padding-right: 16px;
  }

  .research-card {
    padding: 24px 20px;
  }

  .research-content.no-image-content {
    display: block;
  }

  .research-content.no-image-content .research-image.empty-image {
    display: none;
  }

  .research-content.no-image-content .research-text {
    width: 100%;
    max-width: none;
    margin-left: 0;
    padding-left: 0;
  }

  .research-content.no-image-content .research-text h3,
  .research-content.no-image-content .research-text p,
  .research-content.no-image-content .research-text li {
    max-width: none;
    text-align: left;
  }

  .research-content.no-image-content .research-text ol,
  .research-content.no-image-content .research-text ul {
    padding-left: 1.2em;
  }
}