/* ============================================
   歌詞自動表示 — エディトリアルイラスト風スタイル
   モノクロ / 手描き / ネガティブスペース重視
   ============================================ */

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

:root {
  --ink: #1a1a1a;
  --ink-light: #444;
  --ink-muted: #888;
  --ink-faint: #bbb;
  --paper: #ffffff;
  --paper-warm: #fafaf8;
  --border: #e0e0e0;
  --border-light: #f0f0f0;

  --font-serif: 'Noto Serif JP', 'Georgia', serif;
  --font-sans: 'Noto Sans JP', 'Hiragino Kaku Gothic ProN', sans-serif;

  --space-xs: 8px;
  --space-sm: 16px;
  --space-md: 32px;
  --space-lg: 64px;
  --space-xl: 96px;
  --space-2xl: 144px;
}

html {
  scroll-behavior: smooth;
}

body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  font-weight: 300;
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}

/* ============================================
   ナビゲーションバー
   ============================================ */

.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: transparent;
  transition: background 0.25s, border-color 0.25s, box-shadow 0.25s;
  border-bottom: 1px solid transparent;
}

.site-nav.scrolled {
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom-color: var(--border-light);
  box-shadow: 0 1px 0 var(--border-light);
}

.site-nav-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 var(--space-md);
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-nav-logo {
  font-family: var(--font-serif);
  font-size: 14px;
  font-weight: 400;
  color: var(--ink);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.site-nav-links {
  display: flex;
  gap: var(--space-md);
}

.site-nav-links a {
  font-size: 12px;
  font-weight: 300;
  color: var(--ink-muted);
  text-decoration: none;
  letter-spacing: 0.3px;
  transition: color 0.15s;
}

.site-nav-links a:hover {
  color: var(--ink);
}

/* ============================================
   ページトップへ戻るボタン
   ============================================ */

.back-to-top {
  position: fixed;
  bottom: var(--space-md);
  right: var(--space-md);
  z-index: 100;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3px;
  padding: 10px 12px;
  background: var(--paper);
  color: var(--ink-muted);
  border: 1px solid var(--border);
  cursor: pointer;
  font-family: var(--font-sans);
  font-size: 9px;
  font-weight: 400;
  letter-spacing: 1px;
  text-transform: uppercase;
  transition: color 0.15s, border-color 0.15s;
}

.back-to-top:hover {
  color: var(--ink);
  border-color: var(--ink);
}

.back-to-top[hidden] {
  display: none;
}

/* ============================================
   レイアウトユーティリティ
   ============================================ */

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 var(--space-md);
}

.container-narrow {
  max-width: 680px;
}

.divider-line {
  height: 1px;
  background: var(--border);
  margin: 0 var(--space-md);
}

/* ============================================
   ヒーローセクション
   ネガティブスペースたっぷりの上部
   ============================================ */

.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  position: relative;
  overflow: hidden;
  padding-top: 52px; /* ナビバー分 */
}

.hero-negative-space {
  flex: 1;
  min-height: 340px;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}

.illustration-float {
  width: 100%;
  max-width: 840px;
  height: auto;
  opacity: 0.85;
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
}

.hero-content {
  padding: var(--space-xl) var(--space-md) var(--space-2xl);
  max-width: 640px;
  margin: 0 auto;
  text-align: left;
}

.eyebrow {
  font-family: var(--font-sans);
  font-weight: 400;
  font-size: 11px;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: var(--space-sm);
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.eyebrow::before {
  content: '';
  display: inline-block;
  width: 24px;
  height: 1px;
  background: var(--ink-faint);
}

.hero-title {
  font-family: var(--font-serif);
  font-weight: 300;
  font-size: clamp(48px, 8vw, 80px);
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin-bottom: var(--space-md);
}

.hero-sub {
  font-size: 15px;
  color: var(--ink-light);
  line-height: 1.9;
  margin-bottom: var(--space-lg);
  font-weight: 300;
}

.hero-actions {
  display: flex;
  gap: var(--space-sm);
  flex-wrap: wrap;
}

/* ============================================
   ボタン
   ============================================ */

.btn-primary {
  display: inline-block;
  padding: 13px 28px;
  background: var(--ink);
  color: var(--paper);
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 400;
  letter-spacing: 0.5px;
  text-decoration: none;
  border: 1px solid var(--ink);
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
}

.btn-primary:hover {
  background: var(--paper);
  color: var(--ink);
}

.btn-ghost {
  display: inline-block;
  padding: 13px 28px;
  background: transparent;
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 400;
  letter-spacing: 0.5px;
  text-decoration: none;
  border: 1px solid var(--border);
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
}

.btn-ghost:hover {
  border-color: var(--ink);
  background: var(--paper-warm);
}

/* ============================================
   How it works
   ============================================ */

.how-it-works {
  padding: var(--space-2xl) 0;
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-xl);
}

.section-label {
  display: inline-block;
  font-size: 10px;
  font-weight: 400;
  letter-spacing: 3px;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: var(--space-sm);
}

.section-header h2 {
  font-family: var(--font-serif);
  font-weight: 300;
  font-size: clamp(28px, 4vw, 40px);
  letter-spacing: -0.01em;
  color: var(--ink);
  margin-top: 6px;
}

.section-desc {
  font-size: 14px;
  color: var(--ink-muted);
  margin-top: var(--space-sm);
  line-height: 1.8;
}

.steps {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: 0;
  flex-wrap: wrap;
}

.step {
  flex: 1;
  min-width: 200px;
  max-width: 260px;
  text-align: center;
  padding: 0 var(--space-sm);
}

.step-illustration {
  width: 100px;
  height: 100px;
  margin: 0 auto var(--space-md);
}

.step-illustration svg {
  width: 100%;
  height: 100%;
}

.step-number {
  font-family: var(--font-sans);
  font-size: 10px;
  font-weight: 400;
  letter-spacing: 2px;
  color: var(--ink-faint);
  margin-bottom: 10px;
}

.step h3 {
  font-family: var(--font-serif);
  font-weight: 400;
  font-size: 17px;
  color: var(--ink);
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.step p {
  font-size: 13px;
  color: var(--ink-muted);
  line-height: 1.8;
}

.step-connector {
  display: flex;
  align-items: center;
  padding-top: 50px;
  opacity: 0.6;
}

.step-connector svg {
  width: 60px;
  height: 20px;
}

/* ============================================
   検索セクション
   ============================================ */

.search-section {
  padding: var(--space-2xl) 0;
  background: var(--paper-warm);
}

.search-box {
  background: var(--paper);
  border: 1px solid var(--border);
  padding: var(--space-lg);
}

.search-field-group {
  display: flex;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
}

.search-field {
  flex: 1;
}

.search-field label {
  display: block;
  font-size: 10px;
  font-weight: 400;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: 8px;
}

.search-field input {
  width: 100%;
  padding: 12px 14px;
  border: 1px solid var(--border);
  border-radius: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 300;
  outline: none;
  transition: border-color 0.2s;
  -webkit-appearance: none;
}

.search-field input::placeholder {
  color: var(--ink-faint);
}

.search-field input:focus {
  border-color: var(--ink);
}

.btn-search {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 13px 24px;
  background: var(--ink);
  color: var(--paper);
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 400;
  letter-spacing: 0.5px;
  border: none;
  cursor: pointer;
  transition: opacity 0.2s;
  width: 100%;
  justify-content: center;
}

.btn-search:hover {
  opacity: 0.8;
}

.search-note {
  font-size: 11px;
  color: var(--ink-faint);
  text-align: center;
  margin-top: 10px;
  letter-spacing: 0.3px;
}

/* ============================================
   インストールセクション
   ============================================ */

.install-section {
  padding: var(--space-2xl) 0;
}

.install-inner {
  display: flex;
  gap: var(--space-xl);
  align-items: center;
}

.install-illustration {
  flex-shrink: 0;
  width: 180px;
  height: 180px;
}

.install-illustration svg {
  width: 100%;
  height: 100%;
}

.install-text {
  flex: 1;
}

.install-text h2 {
  font-family: var(--font-serif);
  font-weight: 300;
  font-size: clamp(24px, 3vw, 36px);
  letter-spacing: -0.01em;
  color: var(--ink);
  margin: 8px 0 var(--space-sm);
}

.install-text p {
  font-size: 14px;
  color: var(--ink-muted);
  line-height: 1.9;
  margin-bottom: var(--space-md);
}

.install-steps {
  list-style: none;
  margin-top: var(--space-md);
  counter-reset: steps;
}

.install-steps li {
  counter-increment: steps;
  font-size: 13px;
  color: var(--ink-muted);
  line-height: 1.6;
  padding: 8px 0 8px 36px;
  position: relative;
  border-bottom: 1px solid var(--border-light);
}

.install-steps li:last-child { border-bottom: none; }

.install-steps li::before {
  content: counter(steps);
  position: absolute;
  left: 0;
  top: 8px;
  width: 20px;
  height: 20px;
  border: 1px solid var(--border);
  font-size: 10px;
  font-weight: 400;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--ink-faint);
}

.install-steps code {
  font-family: 'SF Mono', 'Fira Code', monospace;
  font-size: 11px;
  background: var(--paper-warm);
  border: 1px solid var(--border-light);
  padding: 1px 5px;
  color: var(--ink-light);
}

/* ============================================
   フッター
   ============================================ */

.footer {
  padding: var(--space-lg) 0 var(--space-md);
  border-top: 1px solid var(--border-light);
  background: var(--paper-warm);
}

.footer-inner {
  text-align: center;
}

.footer-title {
  font-family: var(--font-serif);
  font-size: 16px;
  font-weight: 400;
  color: var(--ink);
  margin-bottom: var(--space-sm);
}

.footer-note {
  font-size: 11px;
  color: var(--ink-faint);
  line-height: 1.9;
  margin-bottom: var(--space-sm);
  max-width: 500px;
  margin-left: auto;
  margin-right: auto;
}

.footer-copy {
  font-size: 10px;
  color: var(--ink-faint);
  letter-spacing: 1px;
}

/* ============================================
   レスポンシブ
   ============================================ */

@media (max-width: 640px) {
  .hero-content {
    padding-bottom: var(--space-xl);
  }

  .step-connector {
    display: none;
  }

  .steps {
    flex-direction: column;
    align-items: center;
    gap: var(--space-lg);
  }

  .step {
    max-width: 100%;
  }

  .search-field-group {
    flex-direction: column;
  }

  .install-inner {
    flex-direction: column;
    text-align: center;
  }

  .install-illustration {
    width: 120px;
    height: 120px;
  }
}

/* ============================================
   フォーカスアクセシビリティ
   ============================================ */

:focus-visible {
  outline: 1px solid var(--ink);
  outline-offset: 3px;
}

a {
  color: inherit;
}