@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=Noto+Sans+JP:wght@400;500;700&display=swap');

:root {
  --bg-color: #FFFFFF;
  --text-color: #202020;
  
  --accent-color: #40BFBF;
  --accent-color-dark: #2C8585; 
  
  --accent-strong: #FF9F7F;
  --accent-strong-dark: #D45B32; 
  
  --aux-color: #BFBF7F;
  --aux-color-dark: #8C8C5C;
  
  --nav-width: 280px;
  --header-height: 60px;
  --card-shadow: 0 4px 6px rgba(32, 32, 32, 0.05), 0 1px 3px rgba(32, 32, 32, 0.1);
  --border-color: rgba(32, 32, 32, 0.15);
}

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

body {
  font-family: 'Inter', 'Noto Sans JP', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent-color-dark);
  text-decoration: none;
  transition: color 0.2s ease, background-color 0.2s ease, border-color 0.2s ease;
}

a:hover {
  color: var(--text-color);
}

ul {
  list-style: none;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-color);
  margin-bottom: 1rem;
  font-weight: 700;
  line-height: 1.3;
}

h1 { font-size: 2.25rem; }
h2 { 
  font-size: 1.75rem; 
  border-bottom: 1px solid var(--border-color); 
  padding-bottom: 0.5rem; 
  margin-top: 2.5rem; 
  margin-bottom: 1.5rem;
}
h3 { font-size: 1.25rem; margin-top: 1.5rem; }
p { margin-bottom: 1rem; }

/* Layout */
.app-container {
  display: flex;
  min-height: 100vh;
}

/* Sidebar Navigation */
.sidebar {
  width: var(--nav-width);
  background-color: #fafafa;
  border-right: 1px solid var(--border-color);
  position: fixed;
  top: 0;
  left: 0;
  height: 100vh;
  overflow-y: auto;
  padding: 2.5rem 1.5rem;
  z-index: 100;
  transition: transform 0.3s ease;
}

.site-brand {
  margin-bottom: 3rem;
}

.site-brand h1 {
  font-size: 1.5rem;
  margin: 0;
  color: var(--text-color);
  border: none;
  padding: 0;
}
.site-brand h1 span {
  color: var(--accent-color-dark);
}
.site-brand p {
  font-size: 0.85rem;
  color: #555;
  margin-top: 0.25rem;
}

.nav-item {
  margin-bottom: 0.5rem;
}

.nav-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1rem;
  color: var(--text-color);
  font-weight: 500;
  border-radius: 6px;
  cursor: pointer;
  background-color: transparent;
}

.nav-link:hover {
  background-color: rgba(64, 191, 191, 0.1);
  color: var(--accent-color-dark);
}

.nav-link.active {
  background-color: rgba(64, 191, 191, 0.15);
  color: var(--accent-color-dark);
  font-weight: 600;
}

.toggle-icon {
  font-size: 0.75rem;
  transition: transform 0.3s ease;
  color: #666;
}

/* Submenu */
.sub-menu {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
  padding-left: 1rem;
}

.sub-menu.open {
  max-height: 400px;
}

/* Nav parent link: text navigates, icon toggles */
.nav-parent {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-parent .toggle-icon {
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  flex-shrink: 0;
}

.sub-menu .nav-link {
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
  font-weight: 400;
  border-left: 2px solid transparent;
  border-radius: 0 6px 6px 0;
}
.sub-menu .nav-link:hover, .sub-menu .nav-link.active {
  background-color: transparent;
  color: var(--accent-color-dark);
  border-left-color: var(--accent-color);
}

/* Main Content */
.main-content {
  flex-grow: 1;
  margin-left: var(--nav-width);
  padding: 4rem;
  max-width: 1000px;
}

/* Mobile Header */
.mobile-header {
  display: none;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
  padding: 0 1.5rem;
  background-color: var(--bg-color);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 90;
}

.mobile-brand {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-color);
}
.mobile-brand span {
  color: var(--accent-color-dark);
}

.hamburger {
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.hamburger-line {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--text-color);
  margin-bottom: 5px;
  transition: all 0.3s ease;
}
.hamburger-line:last-child {
  margin-bottom: 0;
}

/* Overlay for Mobile Nav */
.overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(32, 32, 32, 0.4);
  z-index: 95;
  opacity: 0;
  transition: opacity 0.3s ease;
}
.overlay.show {
  display: block;
  opacity: 1;
}

/* Components */
.hero {
  background: linear-gradient(135deg, rgba(64, 191, 191, 0.1) 0%, rgba(255, 159, 127, 0.15) 100%);
  padding: 4rem 3rem;
  border-radius: 12px;
  margin-bottom: 3rem;
  border-left: 6px solid var(--accent-color);
  position: relative;
}

.hero.bg-home {
  background: linear-gradient(135deg, rgba(32, 32, 32, 0.85) 0%, rgba(32, 32, 32, 0.95) 100%), url('../images/home-bg.png');
  background-size: cover;
  background-position: center;
}
.hero.bg-home h2 {
  color: #FFFFFF;
}
.hero.bg-home p {
  color: rgba(255, 255, 255, 0.9);
}

.page-header.bg-about,
.page-header.bg-research,
.page-header.bg-memo,
.page-header.bg-link,
.page-header.bg-tool,
.page-header.bg-document,
.page-header.bg-database,
.page-header.bg-equipment {
  background-size: cover;
  background-position: center;
  padding: 3rem;
  border-radius: 12px;
}
.page-header.bg-about h1,
.page-header.bg-research h1,
.page-header.bg-memo h1,
.page-header.bg-link h1,
.page-header.bg-tool h1,
.page-header.bg-document h1,
.page-header.bg-database h1,
.page-header.bg-equipment h1 {
  color: #FFFFFF;
  margin: 0;
  border: none;
}
.page-header.bg-about p,
.page-header.bg-research p,
.page-header.bg-memo p,
.page-header.bg-link p,
.page-header.bg-tool p,
.page-header.bg-document p,
.page-header.bg-database p,
.page-header.bg-equipment p {
  color: rgba(255, 255, 255, 0.9);
  margin-top: 0.5rem;
  margin-bottom: 0;
}

/* Blue-green group (#40BFBF): Home, About Us, Research */
.page-header.bg-about {
  background-image: linear-gradient(135deg, rgba(32, 32, 32, 0.85) 0%, rgba(32, 32, 32, 0.95) 100%), url('../images/about-bg.png');
  border-left: 6px solid var(--accent-color);
}
.page-header.bg-research {
  background-image: linear-gradient(135deg, rgba(32, 32, 32, 0.85) 0%, rgba(32, 32, 32, 0.95) 100%), url('../images/research-bg.png');
  border-left: 6px solid var(--accent-color);
}

/* Red group (#FF9F7F): Memo, Document, Tool */
.page-header.bg-memo {
  background-image: linear-gradient(135deg, rgba(32, 32, 32, 0.85) 0%, rgba(32, 32, 32, 0.95) 100%), url('../images/memo-bg.png');
  border-left: 6px solid var(--accent-strong);
}
.page-header.bg-document {
  background-image: linear-gradient(135deg, rgba(32, 32, 32, 0.85) 0%, rgba(32, 32, 32, 0.95) 100%), url('../images/document-bg.png');
  border-left: 6px solid var(--accent-strong);
}
.page-header.bg-tool {
  background-image: linear-gradient(135deg, rgba(32, 32, 32, 0.85) 0%, rgba(32, 32, 32, 0.95) 100%), url('../images/tool-bg.png');
  border-left: 6px solid var(--accent-strong);
}

/* Yellow group (#BFBF7F): Database, Equipment, Link */
.page-header.bg-link {
  background-image: linear-gradient(135deg, rgba(32, 32, 32, 0.85) 0%, rgba(32, 32, 32, 0.95) 100%), url('../images/link-bg.png');
  border-left: 6px solid var(--aux-color);
}
.page-header.bg-database {
  background-image: linear-gradient(135deg, rgba(32, 32, 32, 0.85) 0%, rgba(32, 32, 32, 0.95) 100%), url('../images/database-bg.png');
  border-left: 6px solid var(--aux-color);
}
.page-header.bg-equipment {
  background-image: linear-gradient(135deg, rgba(32, 32, 32, 0.85) 0%, rgba(32, 32, 32, 0.95) 100%), url('../images/equipment-bg.png');
  border-left: 6px solid var(--aux-color);
}

.hero h2 {
  border: none;
  margin-top: 0;
  margin-bottom: 1rem;
  font-size: 2.25rem;
}
.hero p {
  font-size: 1.1rem;
  max-width: 700px;
  color: #333;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.card {
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 1.5rem;
  box-shadow: var(--card-shadow);
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
  display: flex;
  flex-direction: column;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 20px rgba(32, 32, 32, 0.08);
  border-color: var(--accent-color);
}

.tags-container {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.card-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.35rem 0.85rem;
  border-radius: 999px;
  background-color: rgba(64, 191, 191, 0.15);
  color: var(--accent-color-dark);
  width: fit-content;
}
.card-tag.memo {
  background-color: rgba(255, 159, 127, 0.15);
  color: var(--accent-strong-dark);
}
.card-tag.data {
  background-color: rgba(191, 191, 127, 0.15);
  color: var(--aux-color-dark);
}

.card h3 {
  margin-top: 0;
  margin-bottom: 0.75rem;
  font-size: 1.25rem;
}

.card p {
  color: #555;
  font-size: 0.95rem;
  flex-grow: 1;
}

.card-footer {
  margin-top: 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: #777;
  border-top: 1px solid var(--border-color);
  padding-top: 1rem;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  font-weight: 600;
  text-align: center;
  cursor: pointer;
  border: 1px solid transparent;
  font-size: 1rem;
}

.btn-primary {
  background-color: var(--accent-color);
  color: var(--text-color);
}
.btn-primary:hover {
  background-color: #38a8a8;
  color: var(--text-color);
}

.btn-outline {
  background-color: transparent;
  border-color: var(--border-color);
  color: var(--text-color);
}
.btn-outline:hover {
  border-color: var(--accent-color);
  color: var(--accent-color-dark);
  background-color: rgba(64, 191, 191, 0.05);
}

.btn-memo {
  background-color: var(--accent-strong);
  color: #FFFFFF;
}
.btn-memo:hover {
  background-color: var(--accent-strong-dark);
  color: #FFFFFF;
}

/* Alerts */
.alert-construction {
  background-color: rgba(191, 191, 127, 0.2);
  border-left: 6px solid var(--aux-color);
  padding: 2.5rem;
  border-radius: 8px;
  text-align: center;
  margin-top: 2rem;
}
.alert-construction h3 {
  color: var(--aux-color-dark);
  margin-top: 0;
  font-size: 1.5rem;
  border: none;
}
.alert-construction p {
  color: #444;
  font-size: 1.1rem;
}

/* Utilities */
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }
.mt-4 { margin-top: 2rem; }
.text-center { text-align: center; }
.flex-row-gap { display: flex; gap: 1rem; flex-wrap: wrap; }
.page-header p { color: #666; font-size: 1.1rem; }

/* Responsive Design */
@media (max-width: 768px) {
  .app-container {
    flex-direction: column;
  }
  
  .mobile-header {
    display: flex;
  }

  .sidebar {
    transform: translateX(-100%);
    width: var(--nav-width);
    box-shadow: var(--card-shadow);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
    padding: 2rem 1.5rem;
  }
  
  .hero {
    padding: 2.5rem 1.5rem;
  }
  
  .hero h2 {
    font-size: 1.75rem;
  }
}