body{font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Open Sans,Helvetica Neue,sans-serif;margin:0;padding:0;display:flex;flex-direction:column;min-height:100vh;color:#333}header{background-color:#3f51b5;color:#fff;padding:.5rem 1rem;box-shadow:0 2px 4px #0000001a}header nav ul{list-style:none;padding:0;margin:0;display:flex;gap:1rem}header nav a{color:#fff;text-decoration:none;padding:.5rem .8rem;border-radius:4px;transition:background-color .2s ease}header nav a:hover,header nav a.active{background-color:#fff3}main{flex-grow:1;padding:1.5rem;max-width:1200px;margin:0 auto;width:100%;box-sizing:border-box}footer{background-color:#f5f5f5;padding:1rem;text-align:center;margin-top:auto;color:#666;font-size:.9rem}button{padding:.7rem 1.5rem;background-color:#3f51b5;color:#fff;border:none;border-radius:4px;cursor:pointer;font-size:1rem;transition:background-color .2s ease}button:hover{background-color:#303f9f}button:disabled{background-color:#ccc;cursor:not-allowed}