body { background-color: #e6e6e6; /* 薄めの鉄グレー */ color: #222; font-family: "Yu Gothic", "Hiragino Kaku Gothic ProN", Meiryo, sans-serif; line-height: 1.8; padding: 2em; } h1 { font-size: 1.8em; border-bottom: 2px solid #999; padding-bottom: 0.3em; margin-bottom: 1em; } h2 { font-size: 1.3em; margin-t…