/* ============================================
   AI Tech Daily — "Ink & Signal" Theme
   和紙 × サイバーパンク エディトリアルデザイン
   ============================================ */

/* --- CSS Variables --- */
:root {
  /* Base Colors */
  --bg: #FAF7F0;
  --bg-alt: #F0EDE5;
  --bg-card: #FFFFFF;
  --text: #1A1A1A;
  --text-secondary: #5A5A5A;
  --text-muted: #8A8A8A;
  --border: #E0DDD5;
  --border-strong: #C8C4BA;

  /* Brand */
  --accent: #C1272D;
  --accent-light: rgba(193, 39, 45, 0.08);

  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.08);
  --shadow-md: 0 8px 20px rgba(0,0,0,0.12);
  --shadow-demo: 0 2px 8px rgba(0,0,0,0.1);
  --shadow-accent: 0 4px 12px rgba(193, 39, 45, 0.3);

  /* Transitions */
  --transition-hover: transform 0.3s ease, box-shadow 0.3s ease;

  /* Border Radius */
  --radius-lg: 8px;

  /* Perspective Colors */
  --breaking: #C1272D;
  --developer: #0A7E8C;
  --business: #B8860B;
  --beginner: #3D7ABF;
  --ideas: #2D8659;

  /* Dark surfaces */
  --dark-bg: #0D1117;
  --dark-bg-alt: #161B22;
  --dark-text: #FAF7F0;
  --dark-text-secondary: #9CA3AF;

  /* Layout */
  --max-width: 1100px;
  --content-width: 780px;
  --gap: 2rem;
  --radius: 6px;

  /* Typography */
  --font-display: 'Shippori Mincho B1', 'Georgia', serif;
  --font-body: 'M PLUS 1p', 'Hiragino Kaku Gothic ProN', sans-serif;
  --font-mono: 'JetBrains Mono', 'Menlo', monospace;
}

/* --- Skip Link --- */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 999;
  padding: 0.5rem 1rem;
  background: var(--accent);
  color: white;
  font-size: 0.85rem;
}

.skip-link:focus {
  left: 0;
  color: white;
}

/* --- Reset & Base --- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  color: var(--text);
  background-color: var(--bg);
  line-height: 1.8;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

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

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

/* --- Typography --- */
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.3;
  color: var(--text);
}

h1 { font-size: 2.2rem; }
h2 { font-size: 1.6rem; }
h3 { font-size: 1.2rem; }

p {
  margin-bottom: 1rem;
}

blockquote {
  border-left: 3px solid var(--border-strong);
  padding: 0.5rem 1rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin: 1rem 0;
  background: var(--bg-alt);
  border-radius: 0 var(--radius) var(--radius) 0;
}

code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: var(--bg-alt);
  padding: 0.15em 0.4em;
  border-radius: 3px;
}

pre {
  background: var(--dark-bg);
  color: var(--dark-text);
  padding: 1.2rem;
  border-radius: var(--radius);
  overflow-x: auto;
  margin: 1.5rem 0;
}

pre code {
  background: none;
  padding: 0;
  color: inherit;
}

hr {
  border: none;
  height: 1px;
  background: var(--border);
  margin: 2.5rem 0;
}

/* --- Header --- */
.site-header {
  background: var(--dark-bg);
  color: var(--dark-text);
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 3px solid var(--accent);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--gap);
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--dark-text);
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.site-logo:hover {
  color: var(--dark-text);
}

.logo-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: var(--accent);
  color: white;
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  border-radius: 4px;
  letter-spacing: -0.05em;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.site-nav a {
  color: var(--dark-text-secondary);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  transition: color 0.2s ease;
}

.site-nav a:hover {
  color: var(--dark-text);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--dark-text);
  cursor: pointer;
  padding: 0.5rem;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: currentColor;
  margin: 5px 0;
  transition: transform 0.3s ease;
}

/* --- Main Content --- */
.site-main {
  flex: 1;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--gap);
  width: 100%;
}

/* --- Home Page --- */
.home-header {
  text-align: center;
  padding: 3rem 0 2rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: var(--gap);
}

.home-header h1 {
  font-size: 1.6rem;
  font-weight: 400;
  color: var(--text-secondary);
  letter-spacing: 0.08em;
}

.home-header .tagline {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-top: 0.5rem;
}

.posts-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--gap);
}

.post-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.8rem;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  display: flex;
  flex-direction: column;
}

.post-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
}

.post-card.featured {
  grid-column: 1 / -1;
  border-left: 4px solid var(--accent);
}

.post-card .post-date {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  letter-spacing: 0.05em;
  margin-bottom: 0.6rem;
}

.post-card .post-title {
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 0.8rem;
}

.post-card .post-title a {
  color: var(--text);
}

.post-card .post-title a:hover {
  color: var(--accent);
}

.post-card .post-excerpt {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.7;
  flex: 1;
}

.post-card .post-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 1rem;
}

.tag {
  display: inline-block;
  font-size: 0.72rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  background: var(--bg-alt);
  padding: 0.2rem 0.6rem;
  border-radius: 3px;
  letter-spacing: 0.03em;
}

/* --- Article Page --- */
.article {
  max-width: var(--content-width);
  margin: 0 auto;
}

.article-header {
  text-align: center;
  padding: 2.5rem 0 2rem;
  border-bottom: 2px solid var(--border);
  margin-bottom: 2rem;
}

.article-header .article-date {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  letter-spacing: 0.06em;
  margin-bottom: 0.8rem;
}

.article-header h1 {
  font-size: 2rem;
  font-weight: 700;
  line-height: 1.35;
  margin-bottom: 1rem;
}

.article-header .article-tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.4rem;
}

.article-body {
  font-size: 1rem;
  line-height: 1.9;
}

/* --- News Item (H2) Styling --- */
.article-body h2 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-top: 3rem;
  margin-bottom: 1rem;
  padding-bottom: 0.6rem;
  border-bottom: 2px solid var(--accent);
  position: relative;
}

.article-body h2::before {
  content: '';
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 60px;
  height: 2px;
  background: var(--accent);
}

/* --- Perspective Section (H3) Base --- */
.article-body h3 {
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 700;
  margin-top: 1.8rem;
  margin-bottom: 0.8rem;
  padding: 0.6rem 1rem;
  border-radius: var(--radius);
  border-left: 4px solid var(--border-strong);
  background: var(--bg-alt);
}

/* --- Perspective Color Coding --- */
.perspective-breaking h3,
h3[data-perspective="breaking"] {
  border-left-color: var(--breaking);
  background: rgba(193, 39, 45, 0.06);
  color: var(--breaking);
}

.perspective-developer h3,
h3[data-perspective="developer"] {
  border-left-color: var(--developer);
  background: rgba(10, 126, 140, 0.06);
  color: var(--developer);
}

.perspective-business h3,
h3[data-perspective="business"] {
  border-left-color: var(--business);
  background: rgba(184, 134, 11, 0.06);
  color: var(--business);
}

.perspective-beginner h3,
h3[data-perspective="beginner"] {
  border-left-color: var(--beginner);
  background: rgba(61, 122, 191, 0.06);
  color: var(--beginner);
}

.perspective-ideas h3,
h3[data-perspective="ideas"] {
  border-left-color: var(--ideas);
  background: rgba(45, 134, 89, 0.06);
  color: var(--ideas);
}

/* Perspective section wrapper */
.perspective-section {
  margin-bottom: 0.5rem;
  padding: 0 0 0 0.2rem;
  border-left: 1px solid transparent;
  transition: border-color 0.2s ease;
}

.perspective-section:hover {
  border-left-color: var(--border);
}

.perspective-section p,
.perspective-section ul,
.perspective-section ol {
  color: var(--text);
  font-size: 0.95rem;
}


/* --- Lists in articles --- */
.article-body ul,
.article-body ol {
  margin: 0.8rem 0 1.2rem 1.5rem;
}

.article-body li {
  margin-bottom: 0.4rem;
}

.article-body li strong {
  color: var(--text);
}

/* --- Footer --- */
.site-footer {
  background: var(--dark-bg);
  color: var(--dark-text-secondary);
  margin-top: auto;
  border-top: 3px solid var(--accent);
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2.5rem var(--gap);
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--gap);
}

.footer-brand {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--dark-text);
  margin-bottom: 0.5rem;
}

.footer-desc {
  font-size: 0.82rem;
  line-height: 1.6;
  max-width: 320px;
}

.footer-links {
  display: flex;
  gap: 2rem;
}

.footer-links a {
  color: var(--dark-text-secondary);
  font-size: 0.82rem;
  transition: color 0.2s;
}

.footer-links a:hover {
  color: var(--dark-text);
}

.footer-bottom {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.2rem var(--gap);
  border-top: 1px solid var(--dark-bg-alt);
  font-size: 0.75rem;
  text-align: center;
  color: var(--dark-text-secondary);
}

/* --- AdSense Placeholder --- */
.ad-container {
  margin: 2rem 0;
  padding: 1.5rem;
  background: var(--bg-alt);
  border: 1px dashed var(--border-strong);
  border-radius: var(--radius);
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* --- Page (About, Categories, etc.) --- */
.page-header {
  padding: 2rem 0;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2rem;
}

.page-header h1 {
  font-size: 1.8rem;
}

.page-content {
  max-width: var(--content-width);
  margin: 0 auto;
  line-height: 1.9;
}

/* --- Animations --- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.post-card {
  animation: fadeInUp 0.5s ease both;
}

.post-card:nth-child(1) { animation-delay: 0s; }
.post-card:nth-child(2) { animation-delay: 0.08s; }
.post-card:nth-child(3) { animation-delay: 0.16s; }
.post-card:nth-child(4) { animation-delay: 0.24s; }
.post-card:nth-child(5) { animation-delay: 0.32s; }
.post-card:nth-child(6) { animation-delay: 0.40s; }

.article-header {
  animation: fadeInUp 0.6s ease both;
}

.article-body {
  animation: fadeInUp 0.6s ease 0.15s both;
}

/* --- Scrollbar --- */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg);
}

::-webkit-scrollbar-thumb {
  background: var(--border-strong);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* --- Responsive --- */
@media (max-width: 768px) {
  :root {
    --gap: 1.2rem;
  }

  html {
    font-size: 15px;
  }

  .header-inner {
    height: 56px;
  }

  .site-logo {
    font-size: 1.1rem;
  }

  .site-nav {
    display: none;
    position: fixed;
    top: 56px;
    left: 0;
    right: 0;
    background: var(--dark-bg);
    flex-direction: column;
    padding: 1.5rem var(--gap);
    gap: 1.2rem;
    border-bottom: 1px solid var(--dark-bg-alt);
  }

  .site-nav.open {
    display: flex;
  }

  .site-nav a {
    font-size: 1rem;
  }

  .nav-toggle {
    display: block;
  }

  .home-header h1 {
    font-size: 1.3rem;
  }

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

  .post-card.featured {
    border-left-width: 3px;
  }

  .post-card .post-title {
    font-size: 1.15rem;
  }

  .article-header h1 {
    font-size: 1.5rem;
  }

  .article-body h2 {
    font-size: 1.3rem;
    margin-top: 2rem;
  }

  .footer-inner {
    flex-direction: column;
    gap: 1.5rem;
  }

  .footer-links {
    flex-direction: column;
    gap: 0.8rem;
  }

}

@media (max-width: 480px) {
  .post-card {
    padding: 1.2rem;
  }

  .article-header {
    padding: 1.5rem 0;
  }

  .article-body h3 {
    font-size: 0.92rem;
    padding: 0.5rem 0.8rem;
  }
}

/* ============================================
   AI Utilization Hub Design
   ============================================ */

/* ヘッドラインニュースセクション */
.news-headline {
  text-align: center;
  padding: 3rem 2rem;
  background: linear-gradient(135deg, var(--accent) 0%, #A01D2C 100%);
  color: white;
  border-radius: var(--radius);
  margin-bottom: 2rem;
}

.headline-title {
  font-size: 2rem;
  font-family: var(--font-display);
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.headline-desc {
  font-size: 1rem;
  opacity: 0.9;
}

/* 記事アーカイブリンク */
/* archive-link unified definition below */

.archive-button {
  display: inline-block;
  padding: 1rem 2rem;
  background: var(--bg-alt);
  color: var(--text);
  text-decoration: none;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  transition: background 0.2s ease;
}

.archive-button:hover {
  background: var(--border-strong);
  color: white;
}

/* ============================================
   Archive Page
   ============================================ */

.archive-item {
  padding: 1.2rem 0;
  border-bottom: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.archive-item:last-child {
  border-bottom: none;
}

.archive-date {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  letter-spacing: 0.04em;
}

.archive-link {
  text-align: center;
  margin: 3rem 0;
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--text);
  transition: color 0.2s ease;
}

.archive-link:hover {
  color: var(--accent);
}

.archive-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.3rem;
}

.no-posts {
  text-align: center;
  color: var(--text-muted);
  padding: 3rem 0;
  font-size: 0.95rem;
}

/* ============================================
   Hero Section & CTA (初心者向け)
   ============================================ */

.hero-section {
  padding: 80px 20px;
  text-align: center;
  background: linear-gradient(135deg, var(--bg) 0%, #f0ede8 100%);
}

.hero-title {
  font-size: clamp(1.8rem, 5vw, 2.5rem);
  margin-bottom: 1rem;
  color: var(--text);
  font-family: var(--font-display);
  font-weight: 700;
}

.hero-subtitle {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

/* レスポンシブ */
@media (max-width: 768px) {
  .hero-section {
    padding: 60px 20px;
  }
}

/* ============================================
   Chat Demo Styles
   ============================================ */

.chat-demo {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-demo);
  overflow: hidden;
}

.chat-messages {
  padding: 1.5rem;
  min-height: 200px;
  max-height: 300px;
  overflow-y: auto;
  background: var(--bg-alt);
}

.message {
  padding: 0.75rem 1rem;
  margin-bottom: 0.75rem;
  border-radius: var(--radius-lg);
  max-width: 80%;
}

.message.user {
  background: var(--accent);
  color: white;
  margin-left: auto;
}

.message.ai, .message.system {
  background: white;
  color: var(--text);
  border: 1px solid var(--border);
}

.chat-input {
  display: flex;
  padding: 1rem;
  background: var(--bg-card);
  border-top: 1px solid var(--border);
}

.chat-input input {
  flex: 1;
  padding: 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-right: 0.5rem;
  font-family: var(--font-body);
}

.chat-input input:focus {
  outline: none;
  border-color: var(--accent);
}

.chat-input button {
  padding: 0.75rem 1.5rem;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  font-family: var(--font-body);
  transition: var(--transition-hover);
}

.chat-input button:hover {
  filter: brightness(0.9);
}

/* ============================================
   Article Demo Styles
   ============================================ */

.article-demo {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.article-input {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.article-input label {
  font-weight: bold;
  margin-right: 0.5rem;
  font-family: var(--font-body);
}

.article-input input {
  flex: 1;
  padding: 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-family: var(--font-body);
}

.article-input input:focus {
  outline: none;
  border-color: var(--accent);
}

.article-input button {
  padding: 0.75rem 1.5rem;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  font-family: var(--font-body);
  font-weight: bold;
  transition: var(--transition-hover);
}

.article-input button:hover {
  filter: brightness(0.9);
}

.article-output {
  min-height: 150px;
  padding: 1rem;
  background: var(--bg-alt);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.article-output h2 {
  font-size: 1.3rem;
  color: var(--text);
  margin-bottom: 0.5rem;
}

.article-output p {
  color: var(--text);
}

/* ============================================
   Chat Hero Section (チャットボット体験)
   ============================================ */

.chat-hero {
  background: var(--bg-alt);
  padding: 2rem;
  text-align: center;
  border-radius: var(--radius);
  margin: 2rem 0;
}

.chat-hero h2 {
  font-family: var(--font-display);
  font-size: 1.5rem;
  margin-bottom: 1rem;
  color: var(--text);
}

.chat-hero p {
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

.recommended-ai h3 {
  font-size: 1.2rem;
  margin-bottom: 1.5rem;
  color: var(--accent);
}

.ai-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  max-width: 600px;
  margin: 0 auto;
}

.ai-list a {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  transition: var(--transition-hover);
}

.ai-list a:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--accent);
}

.ai-icon {
  font-size: 2rem;
}

.ai-name {
  font-weight: bold;
  color: var(--text);
}

.ai-desc {
  color: var(--text-secondary);
  font-size: 0.9rem;
}