/* ===== リセット・基本設定 ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --primary: #1a56db;
  --primary-dark: #1341b0;
  --primary-light: #e8f0fe;
  --accent: #f59e0b;
  --accent-dark: #d97706;
  --text-primary: #111827;
  --text-secondary: #6b7280;
  --text-light: #9ca3af;
  --bg-white: #ffffff;
  --bg-light: #f9fafb;
  --bg-gray: #f3f4f6;
  --border: #e5e7eb;
  --youtube-red: #ff0000;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.10);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.12);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --font-sans: 'Noto Sans JP', -apple-system, sans-serif;
  --font-serif: 'Noto Serif JP', serif;
  --transition: 0.2s ease;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  color: var(--text-primary);
  background: var(--bg-white);
  line-height: 1.7;
  font-size: 16px;
}

a { text-decoration: none; color: inherit; }
ul { list-style: none; }
img { max-width: 100%; display: block; }

.container {
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== ボタン ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius-sm);
  font-weight: 500;
  font-size: 15px;
  cursor: pointer;
  border: none;
  transition: all var(--transition);
  white-space: nowrap;
}
.btn-primary {
  background: var(--primary);
  color: #fff;
}
.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(26,86,219,0.3);
}
.btn-secondary {
  background: rgba(255,255,255,0.15);
  color: #fff;
  border: 2px solid rgba(255,255,255,0.6);
  backdrop-filter: blur(8px);
}
.btn-secondary:hover {
  background: rgba(255,255,255,0.25);
  transform: translateY(-1px);
}
.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 2px solid var(--primary);
}
.btn-outline:hover {
  background: var(--primary);
  color: #fff;
  transform: translateY(-1px);
}
.btn-youtube {
  background: var(--youtube-red);
  color: #fff;
}
.btn-youtube:hover {
  background: #cc0000;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(255,0,0,0.3);
}
.btn-youtube-large {
  background: var(--youtube-red);
  color: #fff;
  padding: 16px 40px;
  font-size: 17px;
  border-radius: var(--radius-md);
}
.btn-youtube-large:hover {
  background: #cc0000;
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(255,0,0,0.3);
}
.btn-full { width: 100%; justify-content: center; }

/* ===== ナビゲーション ===== */
.navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  padding: 16px 0;
  transition: all 0.3s ease;
}
.navbar.scrolled {
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-sm);
  padding: 12px 0;
}
.nav-container {
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-logo {
  font-size: 20px;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 2px;
}
.logo-ai { color: var(--primary); }
.logo-x { color: var(--accent); margin: 0 2px; }
.logo-tax { color: var(--text-primary); }
.navbar:not(.scrolled) .logo-tax { color: #fff; }
.navbar:not(.scrolled) .logo-ai { color: #93c5fd; }

.nav-menu {
  display: flex;
  align-items: center;
  gap: 36px;
}
.nav-link {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition);
  position: relative;
}
.navbar:not(.scrolled) .nav-link { color: rgba(255,255,255,0.85); }
.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px; left: 0; right: 0;
  height: 2px;
  background: var(--primary);
  transform: scaleX(0);
  transition: transform var(--transition);
}
.nav-link:hover { color: var(--primary); }
.navbar:not(.scrolled) .nav-link:hover { color: #fff; }
.nav-link:hover::after { transform: scaleX(1); }
.nav-link-tool {
  background: rgba(255,255,255,0.15);
  padding: 6px 14px;
  border-radius: 100px;
  border: 1px solid rgba(255,255,255,0.3);
  color: #fff !important;
}
.nav-link-tool::after { display: none; }
.navbar.scrolled .nav-link-tool {
  background: var(--primary-light);
  border-color: transparent;
  color: var(--primary) !important;
}
.nav-link-tool:hover {
  background: rgba(255,255,255,0.3) !important;
}
.navbar.scrolled .nav-link-tool:hover {
  background: #d4e4fd !important;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav-toggle span {
  display: block;
  width: 24px; height: 2px;
  background: var(--text-primary);
  transition: all var(--transition);
}
.navbar:not(.scrolled) .nav-toggle span { background: #fff; }

/* ===== ヒーロー ===== */
.hero {
  min-height: 100vh;
  background: linear-gradient(135deg, #1a1a3e 0%, #1a56db 50%, #0ea5e9 100%);
  display: flex;
  align-items: center;
  padding: 100px 24px 60px;
  position: relative;
  overflow: hidden;
  gap: 48px;
  max-width: 1140px;
  margin: 0 auto;
}
.hero-bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 20% 50%, rgba(99,102,241,0.3) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(14,165,233,0.2) 0%, transparent 40%);
  pointer-events: none;
}
.hero::before {
  content: '';
  position: fixed;
  inset: 0;
  background: linear-gradient(135deg, #1a1a3e 0%, #1a56db 50%, #0ea5e9 100%);
  z-index: -1;
}
section.hero {
  max-width: none;
  width: 100%;
}
.hero-content {
  flex: 1;
  max-width: 560px;
  position: relative;
  z-index: 1;
  margin: 0 auto 0 max(24px, calc((100vw - 1140px)/2 + 24px));
}
.hero-badge {
  display: inline-block;
  background: rgba(255,255,255,0.15);
  color: #fff;
  padding: 6px 16px;
  border-radius: 100px;
  font-size: 13px;
  font-weight: 500;
  margin-bottom: 20px;
  border: 1px solid rgba(255,255,255,0.25);
  backdrop-filter: blur(8px);
}
.hero-title {
  font-size: clamp(36px, 5vw, 56px);
  font-weight: 700;
  color: #fff;
  line-height: 1.25;
  margin-bottom: 20px;
  font-family: var(--font-serif);
}
.gradient-text {
  background: linear-gradient(90deg, #fbbf24, #f59e0b);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-subtitle {
  font-size: 16px;
  color: rgba(255,255,255,0.8);
  margin-bottom: 32px;
  line-height: 1.8;
}
.hero-buttons {
  display: flex;
  gap: 16px;
  margin-bottom: 48px;
  flex-wrap: wrap;
}
.hero-stats {
  display: flex;
  align-items: center;
  gap: 24px;
}
.stat { text-align: center; }
.stat-num {
  display: block;
  font-size: 28px;
  font-weight: 700;
  color: #fff;
  line-height: 1;
}
.stat-label {
  font-size: 12px;
  color: rgba(255,255,255,0.6);
  margin-top: 4px;
}
.stat-divider {
  width: 1px;
  height: 40px;
  background: rgba(255,255,255,0.2);
}

.hero-visual {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  position: relative;
  z-index: 1;
  margin-right: max(24px, calc((100vw - 1140px)/2 + 24px));
  flex-shrink: 0;
}
.hero-card {
  background: rgba(255,255,255,0.1);
  backdrop-filter: blur(12px);
  border: 1px solid rgba(255,255,255,0.2);
  border-radius: var(--radius-md);
  padding: 24px 20px;
  text-align: center;
  color: #fff;
  transition: transform var(--transition), background var(--transition);
}
.hero-card:hover {
  transform: translateY(-4px);
  background: rgba(255,255,255,0.15);
}
.card-icon {
  font-size: 32px;
  margin-bottom: 8px;
}
.hero-card p {
  font-size: 13px;
  font-weight: 500;
}

/* ===== セクション共通 ===== */
.section { padding: 96px 0; }
.section-header {
  text-align: center;
  margin-bottom: 56px;
}
.section-label {
  display: inline-block;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 3px;
  color: var(--primary);
  margin-bottom: 12px;
}
.section-title {
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 700;
  font-family: var(--font-serif);
  margin-bottom: 16px;
}
.section-desc {
  font-size: 16px;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto;
}

/* ===== Aboutセクション ===== */
.about { background: var(--bg-light); }
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: start;
}
.about-profile {
  display: flex;
  gap: 24px;
  align-items: flex-start;
}
.profile-avatar {
  flex-shrink: 0;
}
.avatar-placeholder {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), #0ea5e9);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 40px;
  box-shadow: var(--shadow-md);
}
.profile-info h3 {
  font-size: 22px;
  font-weight: 700;
  margin-bottom: 4px;
}
.profile-role {
  font-size: 14px;
  color: var(--primary);
  font-weight: 500;
  margin-bottom: 12px;
}
.profile-bio {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 16px;
}
.profile-tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}
.tag {
  padding: 4px 12px;
  background: var(--primary-light);
  color: var(--primary);
  border-radius: 100px;
  font-size: 12px;
  font-weight: 500;
}

.about-features {
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.feature-card {
  background: var(--bg-white);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
  display: flex;
  gap: 16px;
  align-items: flex-start;
  transition: box-shadow var(--transition), transform var(--transition);
}
.feature-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.feature-icon { font-size: 24px; flex-shrink: 0; }
.feature-card h4 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 4px;
}
.feature-card p {
  font-size: 14px;
  color: var(--text-secondary);
}

/* ===== ブログセクション ===== */
.blog { background: var(--bg-white); }

.category-filter {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 40px;
}
.filter-btn {
  padding: 8px 20px;
  border: 2px solid var(--border);
  background: transparent;
  color: var(--text-secondary);
  border-radius: 100px;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
  font-family: var(--font-sans);
}
.filter-btn:hover, .filter-btn.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

.blog-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-bottom: 48px;
}
.blog-card.featured {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: 1fr 1fr;
}
.blog-card.featured .card-image { height: 100%; min-height: 240px; }
.blog-card.featured .card-title { font-size: 22px; }

.blog-card {
  background: var(--bg-white);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border);
  transition: box-shadow var(--transition), transform var(--transition);
}
.blog-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
}
.blog-card.hidden { display: none; }

.card-image {
  position: relative;
  overflow: hidden;
}
.image-placeholder {
  height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 48px;
}
.gradient-1 { background: linear-gradient(135deg, #667eea, #764ba2); }
.gradient-2 { background: linear-gradient(135deg, #11998e, #38ef7d); }
.gradient-3 { background: linear-gradient(135deg, #f093fb, #f5576c); }
.gradient-4 { background: linear-gradient(135deg, #4facfe, #00f2fe); }
.gradient-5 { background: linear-gradient(135deg, #f7971e, #ffd200); }

.card-badge {
  position: absolute;
  top: 16px; left: 16px;
  background: var(--accent);
  color: #fff;
  padding: 4px 12px;
  border-radius: 100px;
  font-size: 12px;
  font-weight: 700;
}
.card-body { padding: 24px; }
.card-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 12px;
}
.card-category {
  font-size: 12px;
  font-weight: 600;
  color: var(--primary);
  background: var(--primary-light);
  padding: 3px 10px;
  border-radius: 100px;
}
.card-date {
  font-size: 12px;
  color: var(--text-light);
}
.card-title {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 10px;
  line-height: 1.5;
}
.card-excerpt {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 16px;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.card-link {
  font-size: 14px;
  color: var(--primary);
  font-weight: 600;
  transition: gap var(--transition);
}
.card-link:hover { color: var(--primary-dark); }

.section-cta { text-align: center; }

/* ===== YouTubeセクション ===== */
.youtube { background: var(--bg-light); }

.youtube-featured {
  display: grid;
  grid-template-columns: 3fr 2fr;
  gap: 40px;
  margin-bottom: 48px;
  align-items: center;
}
.youtube-player {
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  aspect-ratio: 16/9;
}
.youtube-embed-placeholder {
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, #1a1a1a, #333);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: rgba(255,255,255,0.7);
  gap: 12px;
}
.play-button {
  width: 64px; height: 64px;
  background: var(--youtube-red);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  color: #fff;
}
.youtube-note { font-size: 12px; color: rgba(255,255,255,0.4); }

.youtube-badge {
  display: inline-block;
  background: var(--youtube-red);
  color: #fff;
  padding: 4px 12px;
  border-radius: 100px;
  font-size: 12px;
  font-weight: 700;
  margin-bottom: 16px;
}
.youtube-info h3 {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 12px;
  line-height: 1.5;
}
.youtube-info p {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 20px;
}
.video-meta {
  display: flex;
  gap: 16px;
  font-size: 13px;
  color: var(--text-light);
  margin-bottom: 24px;
}

.youtube-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-bottom: 56px;
}
.video-card {
  background: var(--bg-white);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition), transform var(--transition);
}
.video-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-4px);
}
.video-thumbnail {
  aspect-ratio: 16/9;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}
.video-play {
  width: 48px; height: 48px;
  background: rgba(255,255,255,0.9);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  color: var(--text-primary);
  cursor: pointer;
  transition: transform var(--transition);
}
.video-card:hover .video-play { transform: scale(1.1); }
.video-duration {
  position: absolute;
  bottom: 8px; right: 8px;
  background: rgba(0,0,0,0.75);
  color: #fff;
  font-size: 12px;
  padding: 2px 6px;
  border-radius: 4px;
}
.video-info { padding: 16px; }
.video-info h4 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 6px;
  line-height: 1.5;
}
.video-date {
  font-size: 12px;
  color: var(--text-light);
}

.youtube-subscribe {
  background: linear-gradient(135deg, #1a1a1a, #333);
  border-radius: var(--radius-lg);
  padding: 48px;
  text-align: center;
  color: #fff;
}
.youtube-subscribe h3 {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 12px;
}
.youtube-subscribe p {
  color: rgba(255,255,255,0.7);
  margin-bottom: 28px;
}

/* ===== ニュースレター ===== */
.newsletter { background: var(--primary); }
.newsletter-box {
  max-width: 700px;
  margin: 0 auto;
  text-align: center;
}
.newsletter-content h2 {
  font-size: 28px;
  font-weight: 700;
  color: #fff;
  margin-bottom: 12px;
}
.newsletter-content p {
  color: rgba(255,255,255,0.8);
  margin-bottom: 32px;
}
.newsletter-form {
  display: flex;
  gap: 12px;
  max-width: 520px;
  margin: 0 auto 16px;
}
.newsletter-input {
  flex: 1;
  padding: 12px 20px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-family: var(--font-sans);
  outline: none;
}
.newsletter-note {
  font-size: 12px;
  color: rgba(255,255,255,0.6);
}

/* ===== お問い合わせ ===== */
.contact { background: var(--bg-white); }
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 60px;
  align-items: start;
}
.contact-info {
  display: flex;
  flex-direction: column;
  gap: 28px;
}
.contact-item {
  display: flex;
  gap: 16px;
  align-items: flex-start;
}
.contact-icon {
  font-size: 24px;
  flex-shrink: 0;
  width: 48px;
  height: 48px;
  background: var(--primary-light);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
}
.contact-item h4 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 4px;
}
.contact-item p {
  font-size: 14px;
  color: var(--text-secondary);
}
.contact-item ul {
  font-size: 14px;
  color: var(--text-secondary);
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.contact-item li::before { content: '・'; }

.contact-form {
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.form-group label {
  font-size: 14px;
  font-weight: 500;
}
.required { color: #ef4444; }
.form-group input,
.form-group select,
.form-group textarea {
  padding: 12px 16px;
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-family: var(--font-sans);
  transition: border-color var(--transition);
  outline: none;
  background: var(--bg-white);
  color: var(--text-primary);
}
.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  border-color: var(--primary);
}
.form-group textarea { resize: vertical; }

/* ===== フッター ===== */
.footer {
  background: var(--text-primary);
  color: rgba(255,255,255,0.7);
  padding: 64px 0 0;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 48px;
  border-bottom: 1px solid rgba(255,255,255,0.1);
  margin-bottom: 32px;
}
.footer-brand .nav-logo { margin-bottom: 16px; display: inline-flex; }
.footer-brand .logo-tax { color: rgba(255,255,255,0.9); }
.footer-brand .logo-ai { color: #93c5fd; }
.footer-brand p {
  font-size: 14px;
  line-height: 1.8;
}
.footer-links h4 {
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 16px;
}
.footer-links ul {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.footer-links a {
  font-size: 14px;
  transition: color var(--transition);
}
.footer-links a:hover { color: #fff; }
.footer-bottom {
  text-align: center;
  padding: 24px 0;
  font-size: 13px;
}

/* ===== アニメーション ===== */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== レスポンシブ ===== */
@media (max-width: 1024px) {
  .hero {
    flex-direction: column;
    text-align: center;
    padding: 120px 24px 60px;
  }
  .hero-content {
    margin: 0 auto;
  }
  .hero-buttons { justify-content: center; }
  .hero-stats { justify-content: center; }
  .hero-visual {
    margin: 0 auto;
    width: 100%;
    max-width: 360px;
  }
  .about-grid { grid-template-columns: 1fr; }
  .blog-grid { grid-template-columns: repeat(2, 1fr); }
  .blog-card.featured {
    grid-column: 1 / -1;
    grid-template-columns: 1fr;
  }
  .youtube-featured { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 100%; left: 0; right: 0;
    background: var(--bg-white);
    flex-direction: column;
    padding: 20px 24px;
    box-shadow: var(--shadow-md);
    gap: 0;
  }
  .nav-menu.open { display: flex; }
  .nav-menu .nav-link { color: var(--text-secondary); padding: 12px 0; border-bottom: 1px solid var(--border); }
  .nav-toggle { display: flex; }
  .navbar:not(.scrolled) { background: rgba(26,26,62,0.8); backdrop-filter: blur(8px); }

  .blog-grid { grid-template-columns: 1fr; }
  .blog-card.featured { grid-column: 1; }
  .youtube-grid { grid-template-columns: 1fr; }
  .newsletter-form { flex-direction: column; }
  .footer-grid { grid-template-columns: 1fr; }
  .section { padding: 64px 0; }
}

@media (max-width: 480px) {
  .hero-title { font-size: 32px; }
  .hero-visual { grid-template-columns: 1fr 1fr; }
  .about-profile { flex-direction: column; align-items: center; text-align: center; }
  .profile-tags { justify-content: center; }
  .contact-item { flex-direction: column; }
}