:root {
  --color-bg: #e5e2db;
  --color-surface: #efece7;
  --color-surface-hover: #faf8f5;
  --color-text: #3a3836;
  --color-text-strong: #22201f;
  --color-text-muted: #6b6863;
  --color-primary: #704ecf;
  --color-primary-hover: #5c3fb0;
  --color-accent: #06b6d4;
  --color-border: #d1cdc5;

  --font-family-base: "Inter", "Noto Sans JP", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  
  --spacing-1: 0.25rem;
  --spacing-2: 0.5rem;
  --spacing-3: 1rem;
  --spacing-4: 1.5rem;
  --spacing-5: 2rem;
  --spacing-6: 3rem;
  --spacing-8: 4rem;

  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-full: 9999px;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.3);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.5);
  
  --transition-fast: 0.15s ease-out;
  --transition-normal: 0.3s ease-out;
}

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

body {
  font-family: var(--font-family-base);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover, a:focus {
  color: var(--color-primary);
  text-decoration: underline;
}

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

h2 { font-size: 1.75rem; letter-spacing: -0.025em; margin-bottom: var(--spacing-4); }
h3 { font-size: 1.25rem; }

/* Layout */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-4);
}

.container-wide {
  max-width: 1600px;
  margin: 0 auto;
  padding: 0 var(--spacing-5);
}

/* Header */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(239, 236, 231, 0.85); /* rgba for #efece7 */
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  padding: var(--spacing-3) 0;
}

.header__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.header__logo {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--color-text-strong);
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
}

.header__logo:hover {
  text-decoration: none;
}

.header__logo-icon {
  color: var(--color-accent);
}

.nav {
  background-color: var(--color-surface);
  border-radius: var(--radius-full);
  padding: var(--spacing-1) var(--spacing-3);
  border: 1px solid var(--color-border);
}

.nav__list {
  display: flex;
  list-style: none;
  gap: var(--spacing-3);
}

.nav__link {
  color: var(--color-text);
  font-weight: 600;
  padding: var(--spacing-2) var(--spacing-3);
  border-radius: var(--radius-full);
  transition: background-color var(--transition-fast), color var(--transition-fast);
  display: inline-block;
}

.nav__link:hover, .nav__link:focus, .nav__link[aria-current="page"] {
  background-color: var(--color-surface-hover);
  color: var(--color-text-strong);
  text-decoration: none;
}

.header__actions {
  display: flex;
  gap: var(--spacing-2);
}

.hamburger {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--color-text-strong);
  cursor: pointer;
}

/* TOC Box for in-article */
.toc-box {
  background-color: var(--color-surface);
  border-radius: var(--radius-md);
  padding: var(--spacing-4);
  margin: var(--spacing-5) 0;
}
.toc-box .widget-title {
  margin-bottom: var(--spacing-2);
}

/* Hero Slider / Featured Area */
.hero-featured {
  padding: var(--spacing-6) 0;
  position: relative;
  overflow: hidden;
  background: linear-gradient(135deg, #efece7 0%, #e5e2db 50%, #e1dfec 100%);
  border-radius: var(--radius-lg);
  margin-top: var(--spacing-4);
}

.hero-card {
  display: flex;
  background-color: var(--color-surface);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.hero-card__image {
  flex: 1.5;
  min-height: 400px;
  background-color: var(--color-border);
  position: relative;
}

.hero-card__image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  position: absolute;
  top: 0; left: 0;
}

.hero-card__content {
  flex: 1;
  padding: var(--spacing-6);
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.hero-card__tag {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 800;
  color: #ffffff;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  margin-bottom: var(--spacing-3);
  align-self: flex-start;
}

.hero-card__title {
  font-size: 2rem;
  margin-bottom: var(--spacing-3);
  line-height: 1.3;
}

.hero-card__title a {
  color: var(--color-text-strong);
}

/* Articles Grid */
.articles-section {
  padding: var(--spacing-6) 0 var(--spacing-8);
}

.section-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  margin-bottom: var(--spacing-5);
  border-bottom: 2px solid var(--color-border);
  padding-bottom: var(--spacing-2);
}

.section-title {
  font-size: 1.75rem;
  color: var(--color-text-strong);
  margin-bottom: 0;
}

.section-link {
  font-weight: 600;
  font-size: 0.95rem;
}

.grid-3col {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-5);
}

/* Article Card */
.card {
  background-color: var(--color-bg);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: transform var(--transition-normal);
  display: flex;
  flex-direction: column;
  position: relative;
}

.card:hover, .card:focus-within {
  transform: translateY(-4px);
}

.card__image-wrapper {
  width: 100%;
  aspect-ratio: 16 / 9;
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin-bottom: var(--spacing-3);
  position: relative;
}

.card__image {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-normal);
}

.card:hover .card__image {
  transform: scale(1.05);
}

.card__meta-top {
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
  margin-bottom: var(--spacing-2);
}

.card__tag {
  font-size: 0.75rem;
  font-weight: 700;
  color: #ffffff;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-sm);
}

.card__date {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.card__title {
  font-size: 1.15rem;
  line-height: 1.5;
  margin-bottom: var(--spacing-2);
}

.card__title a {
  color: var(--color-text-strong);
}

.card__title a::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  z-index: 1;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.6rem 1.25rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
  border: none;
  font-size: 0.95rem;
  text-decoration: none;
}

.btn--primary {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  color: #ffffff;
  box-shadow: 0 4px 15px 0 rgba(232, 28, 255, 0.3);
  border: none;
}

.btn--primary:hover, .btn--primary:focus {
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-primary) 100%);
  box-shadow: 0 6px 20px rgba(232, 28, 255, 0.45);
  transform: translateY(-2px);
  text-decoration: none;
}

.btn--outline {
  background-color: transparent;
  border: 1px solid var(--color-border);
  color: var(--color-text);
}

.btn--outline:hover, .btn--outline:focus {
  border-color: var(--color-text-strong);
  color: var(--color-text-strong);
  text-decoration: none;
}

/* Forms */
.form-group { margin-bottom: var(--spacing-4); }
.form-label { display: block; font-weight: 600; margin-bottom: var(--spacing-2); color: var(--color-text-strong); }
.form-control {
  width: 100%;
  padding: 0.75rem 1rem;
  font-size: 1rem;
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-strong);
  font-family: inherit;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}
.form-control:focus { outline: none; border-color: var(--color-accent); box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.2); }
textarea.form-control { min-height: 150px; resize: vertical; }

/* Footer */
.footer {
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-6) 0;
  background-color: var(--color-surface);
}

.footer__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

/* Breadcrumbs */
.breadcrumbs {
  padding: var(--spacing-4) 0 var(--spacing-2);
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.breadcrumbs a {
  color: var(--color-text);
}

.breadcrumbs a:hover {
  color: var(--color-accent);
}

.breadcrumbs span {
  margin: 0 var(--spacing-1);
}

/* Article Layout */
.article-layout {
  display: flex;
  gap: var(--spacing-6);
  padding: var(--spacing-4) 0 var(--spacing-8);
  align-items: flex-start;
}

.article-main {
  flex: 1;
  min-width: 0; /* Prevents overflow */
  background-color: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: var(--spacing-5) var(--spacing-6);
}

.article-sidebar {
  width: 360px;
  position: sticky;
  top: 100px;
}

/* Article Header */
.article-header {
  margin-bottom: var(--spacing-5);
  border-bottom: 1px solid var(--color-border);
  padding-bottom: var(--spacing-4);
}

.article-header h1 {
  font-size: 2.25rem;
  margin: var(--spacing-3) 0;
}

.article-hero-img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-5);
}

/* Article Content Formatting */
.article-content h2 {
  font-size: 1.75rem;
  margin-top: var(--spacing-6);
  margin-bottom: var(--spacing-3);
  padding-bottom: var(--spacing-2);
  border-bottom: 2px solid var(--color-border);
}

.article-content h3 {
  font-size: 1.35rem;
  margin-top: var(--spacing-5);
  margin-bottom: var(--spacing-2);
}

.article-content p {
  margin-bottom: var(--spacing-4);
}

.article-content ul, .article-content ol {
  margin-bottom: var(--spacing-4);
  padding-left: var(--spacing-4);
}

.article-content li {
  margin-bottom: var(--spacing-2);
}

/* Sidebar Widgets */
.widget {
  background-color: var(--color-surface);
  border-radius: var(--radius-md);
  padding: var(--spacing-4);
  margin-bottom: var(--spacing-4);
}

.widget-title {
  font-size: 1.1rem;
  margin-bottom: var(--spacing-3);
  padding-bottom: var(--spacing-2);
  border-bottom: 1px solid var(--color-border);
}

.toc-list {
  list-style: none;
  font-size: 0.9rem;
}

.toc-list li {
  margin-bottom: var(--spacing-2);
}

.toc-list a {
  color: var(--color-text);
}

.toc-list a:hover {
  color: var(--color-accent);
}

/* Category Filter */
.category-filter {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-2);
  margin-bottom: var(--spacing-5);
}

.category-filter .btn--outline {
  padding: 0.4rem 1rem;
  font-size: 0.85rem;
}

.category-filter .btn--outline.active {
  background-color: var(--color-primary);
  color: var(--color-text-strong);
  border-color: var(--color-primary);
}

@media (max-width: 992px) {
  .hero-card { flex-direction: column; }
  .hero-card__image { min-height: 250px; }
  .grid-3col { grid-template-columns: repeat(2, 1fr); }
  .article-layout { flex-direction: column; }
  .article-sidebar { width: 100%; position: static; }
}

@media (max-width: 768px) {
  .grid-3col { grid-template-columns: 1fr; }
  
  /* Mobile Header / Hamburger */
  .header__inner { position: relative; }
  .nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--color-surface);
    border-radius: var(--radius-md);
    padding: var(--spacing-3);
    margin-top: var(--spacing-2);
    box-shadow: var(--shadow-lg);
  }
  .nav.is-open {
    display: block;
  }
  .nav__list { flex-direction: column; gap: var(--spacing-2); }
.nav__link { padding: var(--spacing-2); width: 100%; display: block; }
  .hamburger { display: block; }
  .header__actions { display: none; }
  
  /* Article adjustments for Mobile Edge-to-Edge */
  .article-sidebar .widget:first-child { display: none; }
  
  .article-main {
    padding: 0;
    background-color: transparent;
  }
  
  /* Make Hero Image Full Bleed (Edge-to-Edge) */
  .article-hero-img {
    margin-left: calc(-1 * var(--spacing-5));
    margin-right: calc(-1 * var(--spacing-5));
    width: calc(100% + (var(--spacing-5) * 2));
    border-radius: 0;
  }
  
  /* Typography Adjustments for Mobile FV */
  .article-header h1 {
    font-size: 1.5rem;
  }
  .hero-card__title {
    font-size: 1.5rem;
  }
}

@media (min-width: 769px) {
  .toc-mobile { display: none; } /* Hide in-article TOC on desktop */
}

/* Utilities for Category Filtering */
.is-hidden {
  display: none !important;
}

.fade-in-up {
  animation: fadeInUp 0.4s ease forwards;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Category Filter Layout */
.category-filter {
  display: flex;
  gap: var(--spacing-2);
  flex-wrap: wrap;
  align-items: center;
}

/* Search Box UI */
.search-box {
  display: flex;
  align-items: center;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  padding: 0.25rem 0.75rem;
}
.search-box input {
  border: none;
  background: transparent;
  outline: none;
  padding: 0.25rem;
  font-size: 0.9rem;
  color: var(--color-text-strong);
  width: 100%;
  max-width: 150px;
}
.search-box button {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1rem;
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
}

@media (max-width: 768px) {
  .search-box input {
    max-width: 100px;
  }
}

/* Search Box UI */
.search-box {
  display: flex;
  align-items: center;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  padding: 0.25rem 0.75rem;
}
.search-box input {
  border: none;
  background: transparent;
  outline: none;
  padding: 0.25rem;
  font-size: 0.9rem;
  color: var(--color-text-strong);
  width: 100%;
  max-width: 150px;
}
.search-box button {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1rem;
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
}

@media (max-width: 768px) {
  .search-box input {
    max-width: none;
  }
}

/* SNS Share Buttons */
.sns-share {
  display: flex;
  gap: var(--spacing-3);
  margin: var(--spacing-5) 0;
  flex-wrap: wrap;
}

.sns-share__btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 600;
  color: #fff;
  text-decoration: none;
  transition: transform 0.2s ease, opacity 0.2s ease;
  line-height: 1;
}

.sns-share__btn svg {
  width: 16px;
  height: 16px;
}

.sns-share__btn:hover {
  transform: translateY(-2px);
  opacity: 0.9;
}

.sns-share__btn--x { background-color: #000000; }
.sns-share__btn--fb { background-color: #0866FF; }
.sns-share__btn--line { background-color: #06C755; }
.sns-share__btn--hatena { background-color: #00A4DE; }
.sns-share__btn--copy { background-color: var(--color-border); color: var(--color-text-strong); }