body{background-image:url('/assets/background.jpg');background-size:cover;background-position:center;color:#fff;margin:0;font-family:Arial,Helvetica,sans-serif;} .container{max-width:1100px;margin:20px auto;padding:16px;background:rgba(0,0,0,0.45);border-radius:12px;} .main-nav a{color:#fff;margin-right:12px;text-decoration:none;} .start-gallery{height:260px;position:relative;border-radius:12px;overflow:hidden;} .start-gallery img{position:absolute;left:0;top:0;width:100%;height:100%;object-fit:cover;opacity:0;transition:opacity 1s;} .start-gallery img.active{opacity:1;}