body { margin:0; font-family: Arial, sans-serif; line-height:1.6; color:#111; background:#fff; }
    header { padding:15px; text-align:center; border-bottom:1px solid #eee; }
    header img { max-width:200px; height:auto; }
    .banner img { width:100%; display:block; height:auto; }
    main { padding:20px; max-width:900px; margin:auto; }