body{color:#ddd;background:#101416;margin:0;font-family:Arial,sans-serif;line-height:1.6}header{border-bottom:1px solid #333;padding:45px 20px}header h1{color:#31c026;max-width:850px;margin:auto;font-size:42px}header p{color:#888;max-width:850px;margin:8px auto 0}main{width:850px;max-width:calc(100% - 30px);margin:40px auto}section{margin-bottom:45px}h2{color:#31c026;margin-bottom:12px;font-size:26px}p{color:#bdbdbd;max-width:750px}.levels{grid-template-columns:1fr 1fr;gap:12px;display:grid}.level{background:#171c20;border:1px solid #30363b;padding:20px}.level h3{color:#fff;margin:5px 0 10px}.level p{margin:0}.easy{border-left:4px solid #31c026}.medium{border-left:4px solid #e0c52b}.hard{border-left:4px solid #e34b4b}.impossible{border-left:4px solid #9b59ff}footer{color:#777;text-align:center;border-top:1px solid #333;padding:25px}@media (width<=650px){.levels{grid-template-columns:1fr}header h1{font-size:32px}}