:root { --key-color: #2980b9; --key-color-light: #ebf5fb; } body { font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, sans-serif; line-height: 1.8; color: #333; background-color: #f9f8f5; margin: 0; padding: 0; } .container { max-width: 800px; margin: 0 auto;…