/* ==========================================
   脳トレブロックパズル道場 - Webサイトスタイル（改善版）
   ダークネイビーを維持しながら視認性を大幅向上
   ========================================== */

/* CSS変数 */
:root {
  /* アプリと同じ配色（より見やすく調整） */
  --primary-dark: #0D1B2A;
  --primary-navy: #1B263B;
  --secondary-navy: #253549;
  --accent-blue: #42A5F5;
  --accent-blue-bright: #64B5F6;
  --accent-blue-dark: #1976D2;
  --accent-amber: #FFD700;
  --accent-amber-bright: #FFE44D;
  --accent-green: #4CAF50;
  --accent-green-bright: #66BB6A;
  --accent-red: #EF5350;
  --white: #FFFFFF;
  
  /* テキストカラー（コントラスト比を大幅改善） */
  --text-primary: rgba(255, 255, 255, 0.98);
  --text-secondary: rgba(255, 255, 255, 0.87);
  --text-tertiary: rgba(255, 255, 255, 0.7);
  --text-disabled: rgba(255, 255, 255, 0.5);
  
  /* グラス効果（より明確に） */
  --glass-bg: rgba(255, 255, 255, 0.12);
  --glass-bg-hover: rgba(255, 255, 255, 0.18);
  --glass-border: rgba(255, 255, 255, 0.25);
  --glass-border-hover: rgba(255, 255, 255, 0.4);
  
  /* シャドウ（より強調） */
  --shadow-sm: 0 2px 12px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 6px 24px rgba(0, 0, 0, 0.25);
  --shadow-lg: 0 12px 48px rgba(0, 0, 0, 0.35);
  --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.45);
  
  /* グロー効果 */
  --glow-blue: 0 0 20px rgba(66, 165, 245, 0.3);
  --glow-amber: 0 0 20px rgba(255, 215, 0, 0.3);
  --glow-green: 0 0 20px rgba(76, 175, 80, 0.3);
  
  /* トランジション */
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-fast: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

/* リセット */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans JP", sans-serif;
  line-height: 1.7;
  color: var(--text-primary);
  background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary-navy) 100%);
  background-attachment: fixed;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* コンテナ */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ==========================================
   ナビゲーション
   ========================================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(13, 27, 42, 0.97);
  backdrop-filter: blur(24px);
  box-shadow: var(--shadow-md);
  z-index: 1000;
  border-bottom: 1px solid var(--glass-border);
}

/* メニューラッパー：スクロール可能を示すグラデーション */
.nav-menu-wrapper {
  position: relative;
  width: 100%;
}

.nav-menu-wrapper::before,
.nav-menu-wrapper::after {
  content: '';
  position: absolute;
  top: 0;
  bottom: 0;
  width: 40px;
  pointer-events: none;
  z-index: 2;
  transition: opacity 0.3s ease;
}

.nav-menu-wrapper::before {
  left: 0;
  background: linear-gradient(to right, rgba(13, 27, 42, 0.97), transparent);
}

.nav-menu-wrapper::after {
  right: 0;
  background: linear-gradient(to left, rgba(13, 27, 42, 0.97), transparent);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.875rem;
  font-size: 1.625rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: 0.5px;
  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
  white-space: nowrap;
  flex-shrink: 0;
}

.nav-brand span {
  white-space: nowrap;
}

.nav-brand i {
  font-size: 2rem;
  color: var(--accent-amber);
  filter: drop-shadow(var(--glow-amber));
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 2.25rem;
  width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0.5rem 0;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
  scrollbar-color: var(--accent-blue) var(--glass-bg);
}

/* Webkit（Chrome、Safari）用のスクロールバースタイル */
.nav-menu::-webkit-scrollbar {
  height: 6px;
}

.nav-menu::-webkit-scrollbar-track {
  background: var(--glass-bg);
  border-radius: 3px;
}

.nav-menu::-webkit-scrollbar-thumb {
  background: var(--accent-blue);
  border-radius: 3px;
  transition: var(--transition);
}

.nav-menu::-webkit-scrollbar-thumb:hover {
  background: var(--accent-blue-bright);
}

.nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 600;
  font-size: 1.05rem;
  transition: var(--transition);
  position: relative;
  padding: 0.5rem 0;
  white-space: nowrap;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-blue), var(--accent-blue-bright));
  transition: width 0.3s ease;
  border-radius: 2px;
}

.nav-link:hover {
  color: var(--text-primary);
}

.nav-link:hover::after {
  width: 100%;
}

/* 言語スイッチャー */
.language-switcher {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  padding: 0.625rem 1.25rem;
  background: var(--glass-bg);
  border: 1.5px solid var(--glass-border);
  border-radius: 14px;
  backdrop-filter: blur(12px);
  transition: var(--transition);
}

.language-switcher:hover {
  background: var(--glass-bg-hover);
  border-color: var(--glass-border-hover);
}

.language-switcher i {
  color: var(--accent-blue-bright);
  font-size: 1.1rem;
}

.language-switcher select {
  background: transparent;
  border: none;
  color: var(--text-primary);
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  outline: none;
  padding: 0.25rem;
}

.language-switcher select option {
  background: var(--secondary-navy);
  color: var(--text-primary);
  font-weight: 600;
}

/* モバイルメニュー */
.nav-toggle {
  display: none; /* 横スクロールメニューを使用するため非表示 */
  flex-direction: column;
  gap: 6px;
  cursor: pointer;
  padding: 8px;
}

.bar {
  width: 28px;
  height: 3px;
  background: var(--text-primary);
  border-radius: 3px;
  transition: var(--transition);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

/* ==========================================
   ヒーローセクション
   ========================================== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 80px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 900px;
  height: 900px;
  background: radial-gradient(circle, rgba(66, 165, 245, 0.2) 0%, transparent 70%);
  border-radius: 50%;
  animation: pulse 8s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { 
    transform: scale(1); 
    opacity: 0.6; 
  }
  50% { 
    transform: scale(1.15); 
    opacity: 0.4; 
  }
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
  position: relative;
  z-index: 1;
}

.hero-text h1 {
  font-size: 3.75rem;
  font-weight: 800;
  margin-bottom: 1.75rem;
  line-height: 1.15;
  background: linear-gradient(135deg, var(--white) 0%, var(--accent-blue-bright) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-shadow: 0 4px 20px rgba(66, 165, 245, 0.3);
  letter-spacing: -0.5px;
}

.hero-text .subtitle {
  font-size: 1.625rem;
  color: var(--text-secondary);
  margin-bottom: 2.25rem;
  font-weight: 400;
  line-height: 1.5;
  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

.hero-text p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  margin-bottom: 2.75rem;
  line-height: 1.9;
}

.cta-buttons {
  display: flex;
  gap: 1.25rem;
  flex-wrap: wrap;
}

.btn-primary,
.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.875rem;
  padding: 1.125rem 2.25rem;
  border-radius: 14px;
  font-weight: 700;
  font-size: 1.125rem;
  text-decoration: none;
  transition: var(--transition);
  border: none;
  cursor: pointer;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
  letter-spacing: 0.3px;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent-blue) 0%, var(--accent-blue-dark) 100%);
  color: var(--white);
  box-shadow: 0 8px 24px rgba(66, 165, 245, 0.4);
}

.btn-primary:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 36px rgba(66, 165, 245, 0.5);
  filter: brightness(1.1);
}

.btn-secondary {
  background: var(--glass-bg);
  color: var(--white);
  border: 2px solid var(--glass-border);
  backdrop-filter: blur(12px);
}

.btn-secondary:hover {
  background: var(--glass-bg-hover);
  border-color: var(--glass-border-hover);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

/* ヒーロー画像エリア */
.hero-image {
  position: relative;
}

.app-image,
.app-icon {
  width: 100%;
  max-width: 420px;
  margin: 0 auto;
  background: var(--glass-bg);
  padding: 2.5rem;
  border-radius: 28px;
  border: 2px solid var(--glass-border);
  backdrop-filter: blur(16px);
  box-shadow: var(--shadow-xl);
  text-align: center;
  min-height: 520px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

.app-image:hover,
.hero-image:hover .app-icon {
  border-color: var(--glass-border-hover);
  box-shadow: 0 20px 70px rgba(0, 0, 0, 0.5);
}

.app-image i {
  font-size: 11rem;
  color: var(--accent-blue);
  opacity: 0.4;
  filter: drop-shadow(var(--glow-blue));
}

/* ブロックパズル風の浮遊要素 */
.floating-elements {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 2;
}

.puzzle-block {
  position: absolute;
  display: grid;
  grid-template-columns: repeat(2, 30px);
  grid-template-rows: repeat(2, 30px);
  gap: 3px;
  animation: floatBlock 6s ease-in-out infinite;
  filter: drop-shadow(0 4px 12px rgba(0, 0, 0, 0.3));
}

.block-cell {
  width: 30px;
  height: 30px;
  border-radius: 6px;
  box-shadow: 
    inset 0 2px 4px rgba(255, 255, 255, 0.3),
    inset 0 -2px 4px rgba(0, 0, 0, 0.2),
    0 4px 12px rgba(0, 0, 0, 0.2);
  position: relative;
  transition: var(--transition);
}

/* ブロックのハイライト効果 */
.block-cell::before {
  content: '';
  position: absolute;
  top: 3px;
  left: 3px;
  right: 3px;
  height: 40%;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.4) 0%, transparent 100%);
  border-radius: 4px 4px 0 0;
}

/* テトリス風のL字型ブロック（青） */
.puzzle-block-1 {
  top: 8%;
  left: 10%;
  animation-delay: 0s;
}

.puzzle-block-1 .block-cell {
  background: linear-gradient(135deg, #42A5F5 0%, #1E88E5 100%);
}

.puzzle-block-1 .block-cell:nth-child(3) {
  opacity: 0;
  pointer-events: none;
}

/* T字型ブロック（黄色） */
.puzzle-block-2 {
  top: 15%;
  right: 8%;
  animation-delay: 1s;
}

.puzzle-block-2 .block-cell {
  background: linear-gradient(135deg, #FFD700 0%, #FFA000 100%);
}

.puzzle-block-2 .block-cell:nth-child(4) {
  opacity: 0;
  pointer-events: none;
}

/* Z字型ブロック（緑） */
.puzzle-block-3 {
  bottom: 20%;
  left: 5%;
  animation-delay: 2s;
}

.puzzle-block-3 .block-cell {
  background: linear-gradient(135deg, #4CAF50 0%, #388E3C 100%);
}

.puzzle-block-3 .block-cell:nth-child(1) {
  opacity: 0;
  pointer-events: none;
}

/* 正方形ブロック（紫） */
.puzzle-block-4 {
  bottom: 12%;
  right: 12%;
  animation-delay: 3s;
}

.puzzle-block-4 .block-cell {
  background: linear-gradient(135deg, #AB47BC 0%, #8E24AA 100%);
}

/* I字型ブロック（赤） */
.puzzle-block-5 {
  top: 50%;
  right: 5%;
  display: grid;
  grid-template-columns: 30px;
  grid-template-rows: repeat(3, 30px);
  animation-delay: 4s;
}

.puzzle-block-5 .block-cell {
  background: linear-gradient(135deg, #EF5350 0%, #D32F2F 100%);
}

/* 小さなブロック（オレンジ） */
.puzzle-block-6 {
  top: 35%;
  left: 8%;
  display: grid;
  grid-template-columns: 30px;
  grid-template-rows: repeat(2, 30px);
  animation-delay: 5s;
}

.puzzle-block-6 .block-cell {
  background: linear-gradient(135deg, #FF9800 0%, #F57C00 100%);
}

/* フロートアニメーション */
@keyframes floatBlock {
  0%, 100% {
    transform: translateY(0) rotate(0deg);
  }
  25% {
    transform: translateY(-15px) rotate(3deg);
  }
  50% {
    transform: translateY(-8px) rotate(-2deg);
  }
  75% {
    transform: translateY(-20px) rotate(2deg);
  }
}

/* ホバー時のブロックアニメーション */
.hero-image:hover .puzzle-block {
  animation-play-state: paused;
}

.hero-image:hover .block-cell {
  transform: scale(1.1);
}

/* ヒーローボタン */
.hero-buttons {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 1.25rem;
  flex-wrap: wrap;
}

/* プライバシーリンク（ヒーロー内） */
.privacy-link {
  position: relative;
  display: grid;
  place-items: center;  /* 1行で完結！ */
  padding: 2rem 0 1rem;
}

.privacy-link a {
  display: inline-flex;
  align-items: center;
  gap: 0.625rem;
  padding: 0.75rem 1.5rem;
  background: var(--glass-bg);
  border: 1.5px solid var(--glass-border);
  border-radius: 12px;
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  transition: var(--transition);
  backdrop-filter: blur(12px);
}

.privacy-link a:hover {
  background: var(--glass-bg-hover);
  border-color: var(--accent-blue-bright);
  color: var(--text-primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

/* ==========================================
   セクション共通
   ========================================== */
.section {
  padding: 6rem 0;
  position: relative;
}

.section-title {
  text-align: center;
  margin-bottom: 4.5rem;
}

.section-title h2 {
  font-size: 2.75rem;
  font-weight: 800;
  margin-bottom: 1.25rem;
  background: linear-gradient(135deg, var(--white) 0%, var(--accent-blue-bright) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-shadow: 0 4px 16px rgba(66, 165, 245, 0.3);
  letter-spacing: -0.5px;
}

.section-subtitle {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto;
  line-height: 1.8;
}

/* ==========================================
   特徴セクション
   ========================================== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2.5rem;
}

.feature-item {
  background: var(--glass-bg);
  padding: 3rem;
  border-radius: 24px;
  border: 2px solid var(--glass-border);
  backdrop-filter: blur(16px);
  transition: var(--transition);
  text-align: center;
  box-shadow: var(--shadow-sm);
}

.feature-item:hover {
  transform: translateY(-12px);
  box-shadow: var(--shadow-lg);
  border-color: var(--accent-blue);
  background: var(--glass-bg-hover);
}

.feature-icon {
  width: 90px;
  height: 90px;
  margin: 0 auto 1.75rem;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--accent-blue) 0%, var(--accent-blue-dark) 100%);
  border-radius: 22px;
  font-size: 2.75rem;
  color: var(--white);
  box-shadow: 0 8px 24px rgba(66, 165, 245, 0.4);
  transition: var(--transition);
}

.feature-item:hover .feature-icon {
  transform: scale(1.1) rotateY(10deg);
  box-shadow: 0 12px 32px rgba(66, 165, 245, 0.5);
}

.feature-item h3 {
  font-size: 1.625rem;
  margin-bottom: 1.125rem;
  color: var(--text-primary);
  font-weight: 700;
  letter-spacing: 0.3px;
}

.feature-item p {
  color: var(--text-secondary);
  line-height: 1.85;
  font-size: 1.05rem;
}

/* ==========================================
   スクリーンショットセクション
   ========================================== */
.screenshots-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2.5rem;
}

.screenshot-item {
  position: relative;
  cursor: pointer;
  border-radius: 24px;
  overflow: hidden;
  transition: var(--transition);
}

.screenshot-item:hover {
  transform: scale(1.08);
}

.screenshot-frame {
  background: var(--glass-bg);
  padding: 2rem;
  border-radius: 24px;
  border: 2px solid var(--glass-border);
  backdrop-filter: blur(16px);
  min-height: 440px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.screenshot-item:hover .screenshot-frame {
  border-color: var(--accent-blue);
  box-shadow: var(--shadow-lg);
  background: var(--glass-bg-hover);
}

.screenshot-frame i {
  font-size: 6rem;
  color: var(--accent-blue);
  opacity: 0.4;
}

.screenshot-label {
  text-align: center;
  margin-top: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  font-size: 1.125rem;
  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

/* ==========================================
   モーダル
   ========================================== */
.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(13, 27, 42, 0.96);
  backdrop-filter: blur(12px);
  z-index: 2000;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.modal.active {
  display: flex;
}

.modal-content {
  position: relative;
  max-width: 90%;
  max-height: 90%;
  animation: modalZoom 0.3s ease-out;
}

@keyframes modalZoom {
  from {
    transform: scale(0.7);
    opacity: 0;
  }
  to {
    transform: scale(1);
    opacity: 1;
  }
}

.modal-close {
  position: absolute;
  top: -20px;
  right: -20px;
  background: rgba(239, 83, 80, 0.9);
  color: var(--white);
  border: none;
  font-size: 1.75rem;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  box-shadow: 0 4px 16px rgba(239, 83, 80, 0.4);
}

.modal-close:hover {
  background: var(--accent-red);
  transform: rotate(90deg) scale(1.1);
  box-shadow: 0 6px 20px rgba(239, 83, 80, 0.6);
}

.modal-image {
  max-width: 100%;
  max-height: 100%;
  border-radius: 24px;
  box-shadow: var(--shadow-xl);
}

/* ==========================================
   ダウンロードセクション
   ========================================== */
.download-section {
  background: linear-gradient(135deg, rgba(66, 165, 245, 0.15) 0%, rgba(25, 118, 210, 0.15) 100%);
  border: 2px solid var(--glass-border);
  border-radius: 28px;
  padding: 4.5rem 2.5rem;
  text-align: center;
  box-shadow: var(--shadow-md);
  backdrop-filter: blur(12px);
}

.store-buttons {
  display: flex;
  justify-content: center;
  gap: 2.5rem;
  flex-wrap: wrap;
  margin-top: 2.5rem;
}

.store-link {
  transition: var(--transition);
  display: block;
}

.store-link:hover {
  transform: translateY(-6px);
}

.store-badge {
  height: 64px;
  width: auto;
  filter: drop-shadow(0 6px 16px rgba(0, 0, 0, 0.3));
  transition: var(--transition);
}

.store-link:hover .store-badge {
  filter: drop-shadow(0 8px 24px rgba(66, 165, 245, 0.5));
}

/* ==========================================
   プライバシーポリシーセクション
   ========================================== */
.privacy-content {
  background: var(--glass-bg);
  padding: 3.5rem;
  border-radius: 24px;
  border: 2px solid var(--glass-border);
  backdrop-filter: blur(16px);
  max-width: 960px;
  margin: 0 auto;
  box-shadow: var(--shadow-md);
}

.privacy-content h3 {
  font-size: 2rem;
  margin: 2.5rem 0 1.25rem;
  color: var(--text-primary);
  font-weight: 700;
  letter-spacing: 0.3px;
}

.privacy-content h4 {
  font-size: 1.5rem;
  margin: 2rem 0 1rem;
  color: var(--accent-blue-bright);
  font-weight: 600;
}

.privacy-content p {
  margin-bottom: 1.25rem;
  line-height: 1.9;
  color: var(--text-secondary);
  font-size: 1.05rem;
}

.privacy-content ul {
  margin: 1.25rem 0;
  padding-left: 2.5rem;
}

.privacy-content li {
  margin-bottom: 0.75rem;
  line-height: 1.85;
  color: var(--text-secondary);
  font-size: 1.05rem;
}

.privacy-content a {
  color: var(--accent-blue-bright);
  text-decoration: none;
  transition: var(--transition);
  font-weight: 600;
  border-bottom: 1px solid transparent;
}

.privacy-content a:hover {
  color: var(--white);
  border-bottom-color: var(--white);
}

/* ==========================================
   お問い合わせフォーム
   ========================================== */
.contact-container {
  max-width: 840px;
  margin: 0 auto;
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 0.625rem;
  color: var(--accent-blue-bright);
  text-decoration: none;
  font-weight: 700;
  font-size: 1.05rem;
  margin-bottom: 2.5rem;
  transition: var(--transition);
}

.back-link:hover {
  gap: 1.25rem;
  color: var(--white);
}

.form-group {
  margin-bottom: 2.25rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.875rem;
  font-weight: 700;
  color: var(--text-primary);
  font-size: 1.125rem;
  letter-spacing: 0.3px;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 1.125rem 1.5rem;
  background: var(--glass-bg);
  border: 2px solid var(--glass-border);
  border-radius: 14px;
  color: var(--text-primary);
  font-size: 1.05rem;
  font-family: inherit;
  transition: var(--transition);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-sm);
}

.form-group input::placeholder,
.form-group textarea::placeholder {
  color: var(--text-tertiary);
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--accent-blue-bright);
  box-shadow: 0 0 0 4px rgba(66, 165, 245, 0.15);
  background: var(--glass-bg-hover);
}

.form-group textarea {
  min-height: 220px;
  resize: vertical;
  line-height: 1.8;
}

.error-message {
  color: var(--accent-red);
  font-size: 0.95rem;
  margin-top: 0.625rem;
  display: none;
  font-weight: 600;
}

.error-message.active {
  display: block;
}

.success-message {
  background: linear-gradient(135deg, var(--accent-green) 0%, var(--accent-green-bright) 100%);
  color: var(--white);
  padding: 2.5rem;
  border-radius: 20px;
  margin-bottom: 2.5rem;
  text-align: center;
  box-shadow: 0 8px 24px rgba(76, 175, 80, 0.4);
}

.success-message i {
  font-size: 3.5rem;
  margin-bottom: 1.25rem;
  display: block;
  filter: drop-shadow(0 4px 12px rgba(0, 0, 0, 0.2));
}

.success-message h3 {
  font-size: 1.625rem;
  margin-bottom: 0.625rem;
  font-weight: 700;
}

.submit-btn {
  width: 100%;
  padding: 1.375rem;
  background: linear-gradient(135deg, var(--accent-blue) 0%, var(--accent-blue-dark) 100%);
  color: var(--white);
  border: none;
  border-radius: 14px;
  font-size: 1.25rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.875rem;
  box-shadow: 0 8px 24px rgba(66, 165, 245, 0.4);
  letter-spacing: 0.3px;
}

.submit-btn:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 36px rgba(66, 165, 245, 0.5);
  filter: brightness(1.1);
}

/* ==========================================
   フッター
   ========================================== */
.footer {
  background: rgba(13, 27, 42, 0.98);
  border-top: 2px solid var(--glass-border);
  padding: 3.5rem 0 2rem;
  margin-top: 6rem;
  box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.2);
}

.footer-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-bottom: 2.5rem;
  gap: 2rem;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.875rem;
  font-size: 1.625rem;
  font-weight: 700;
  color: var(--text-primary);
}

.footer-brand i {
  font-size: 2rem;
  color: var(--accent-amber);
  filter: drop-shadow(var(--glow-amber));
}

.footer-links {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 3rem;
  flex-wrap: wrap;
}

.footer-links a {
  color: var(--text-secondary);
  text-decoration: none;
  transition: var(--transition);
  font-weight: 600;
  font-size: 1.05rem;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.footer-links a:hover {
  color: var(--text-primary);
  transform: translateY(-2px);
}

.footer-links a i {
  font-size: 1.1rem;
}

.footer-home {
  margin-top: 1rem;
}

.footer-home a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  background: var(--glass-bg);
  border: 2px solid var(--glass-border);
  border-radius: 50%;
  color: var(--white);
  font-size: 1.625rem;
  transition: var(--transition);
  text-decoration: none;
  box-shadow: var(--shadow-sm);
}

.footer-home a:hover {
  background: var(--accent-blue);
  border-color: var(--accent-blue-bright);
  transform: scale(1.15);
  box-shadow: var(--shadow-md);
}

.footer-bottom {
  text-align: center;
  padding-top: 2.5rem;
  border-top: 1px solid var(--glass-border);
}

.footer-bottom p {
  color: var(--text-tertiary);
  font-size: 0.95rem;
}

/* ==========================================
   レスポンシブデザイン
   ========================================== */
@media (max-width: 768px) {
  /* ナビゲーション */
  .nav-container {
    padding: 0.875rem 1rem;
    gap: 0.75rem;
  }
  
  .nav-brand {
    font-size: 1.25rem;
  }
  
  .nav-brand i {
    font-size: 1.5rem;
  }
  
  .nav-toggle {
    display: none; /* 横スクロールメニューを使用 */
  }

  .nav-toggle.active .bar:nth-child(1) {
    transform: none;
  }

  .nav-toggle.active .bar:nth-child(2) {
    opacity: 1;
  }

  .nav-toggle.active .bar:nth-child(3) {
    transform: none;
  }

  .nav-menu {
    position: static;
    background: transparent;
    backdrop-filter: none;
    flex-direction: row;
    padding: 0.5rem 0;
    border-bottom: none;
    transform: translateX(0);
    box-shadow: none;
    gap: 1.5rem;
    justify-content: flex-start;
  }

  .nav-menu.active {
    transform: translateX(0);
  }
  
  .nav-link {
    white-space: nowrap;
    width: auto;
    text-align: center;
    padding: 0.75rem 1rem;
    font-size: 1rem;
    background: var(--glass-bg);
    border-radius: 8px;
    border: 1px solid var(--glass-border);
  }
  
  .nav-link:hover {
    background: var(--glass-bg-hover);
  }
  
  .nav-link::after {
    display: none; /* モバイルでは下線を非表示 */
  }
  
  .language-switcher {
    margin-top: 0;
    flex-shrink: 0;
  }

  /* ヒーロー */
  .hero-content {
    grid-template-columns: 1fr;
    gap: 3rem;
  }

  .hero-text h1 {
    font-size: 2.75rem;
  }

  .hero-text .subtitle {
    font-size: 1.375rem;
  }

  .hero-text p {
    font-size: 1.05rem;
  }

  .hero-buttons {
    flex-direction: column;
    width: 100%;
  }

  .hero-buttons .btn {
    width: 100%;
    justify-content: center;
  }

  /* ブロックパズル - モバイルサイズ調整 */
  .puzzle-block {
    grid-template-columns: repeat(2, 24px);
    grid-template-rows: repeat(2, 24px);
    gap: 2px;
  }

  .block-cell {
    width: 24px;
    height: 24px;
    border-radius: 5px;
  }

  .puzzle-block-5 {
    grid-template-columns: 24px;
    grid-template-rows: repeat(3, 24px);
  }

  .puzzle-block-6 {
    grid-template-columns: 24px;
    grid-template-rows: repeat(2, 24px);
  }

  /* プライバシーリンク */
  .privacy-link {
    bottom: 0.25rem;  /* 1rem → 0.25rem に変更してより下に配置 */
  }

  .privacy-link a {
    font-size: 0.875rem;
    padding: 0.625rem 1.25rem;
  }

  /* セクション */
  .section {
    padding: 4rem 0;
  }

  .section-title h2 {
    font-size: 2.25rem;
  }

  .section-subtitle {
    font-size: 1.125rem;
  }

  /* 特徴 */
  .features-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  /* スクリーンショット */
  .screenshots-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  /* ダウンロード */
  .download-section {
    padding: 3.5rem 2rem;
  }

  /* ストアボタン */
  .store-buttons {
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
  }

  /* フッター */
  .footer-content {
    flex-direction: column;
    text-align: center;
    gap: 1.5rem;
  }

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

  .footer-home {
    margin-top: 0.5rem;
  }

  /* モーダル */
  .modal-close {
    top: -15px;
    right: -15px;
    width: 50px;
    height: 50px;
    font-size: 1.5rem;
  }
}

/* タブレット */
@media (min-width: 769px) and (max-width: 1024px) {
  .hero-content {
    gap: 3rem;
  }

  .hero-text h1 {
    font-size: 3.25rem;
  }

  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .screenshots-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* 小さい画面用 */
@media (max-width: 480px) {
  .nav-container {
    padding: 0.75rem 0.875rem;
    gap: 0.5rem;
  }
  
  .nav-brand {
    font-size: 1.125rem;
    gap: 0.5rem;
  }
  
  .nav-brand i {
    font-size: 1.375rem;
  }
  
  .nav-menu {
    gap: 1rem;
  }
  
  .nav-link {
    padding: 0.625rem 0.875rem;
    font-size: 0.9rem;
  }
  
  .language-switcher {
    padding: 0.5rem 1rem;
  }
  
  .language-switcher select {
    font-size: 0.9rem;
  }
}

/* アニメーション */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(40px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideInFromLeft {
  from {
    opacity: 0;
    transform: translateX(-40px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes slideInFromRight {
  from {
    opacity: 0;
    transform: translateX(40px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.fade-in {
  animation: fadeIn 0.8s ease-out;
}

.slide-in-left {
  animation: slideInFromLeft 0.8s ease-out;
}

.slide-in-right {
  animation: slideInFromRight 0.8s ease-out;
}

/* パフォーマンス最適化 */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}