body { font-family: "Hiragino Kaku Gothic Pro", "Meiryo", sans-serif; line-height: 1.8; color: #333; background: #fafafa; padding: 20px; max-width: 800px; margin: auto; } h1, h2, h3 { color: #2c3e50; } h1 { font-size: 24px; } h2 { font-size: 20px; margin-top: 40px; } p { margin-bottom: 20px; } .happ…