html,body{margin:0;padding:0;background-color:#036;font-family:Arial,sans-serif;overflow-x:hidden;min-height:100vh}.lesson-box{background-color:#fff;border-radius:1rem;padding:2rem;box-shadow:0 10px 30px #00000026;max-width:900px;margin:2rem auto}.lesson-box img.logo{display:block;max-width:35%;height:auto;margin:0 auto 1rem}.chord-grid{display:flex;flex-wrap:wrap;gap:.5rem;justify-content:center}.chord-grid img{width:200px;height:auto;flex:0 0 auto}