body{color:#1a1a1a;background:#fafafa;margin:0;padding:2rem 1rem;font-family:system-ui,sans-serif;line-height:1.6}main{max-width:42rem;margin:0 auto}a{color:#0b5fff}h1{text-align:center;margin-bottom:.25rem}#level-select{padding:0 .5rem}#level-select h2{text-align:center}#level-grid{grid-template-columns:repeat(auto-fill,minmax(3.5rem,1fr));gap:.5rem;margin-top:1rem;display:grid}button.level{cursor:pointer;border:none;border-radius:.5rem;min-height:3rem;font-size:1.1rem}button.level.locked{color:#9a9a9a;cursor:not-allowed;background:#e2e2e2}button.level.unlocked{color:#fff;background:#0b5fff}button.level.completed{color:#fff;background:#1f9d55}#game{background:#fff;border:1px solid #e6e6e6;border-radius:1rem;padding:2rem 2.5rem 2.5rem;box-shadow:0 8px 24px #0000000f}#game #back-to-levels{color:#0b5fff;cursor:pointer;background:0 0;border:none;padding:0;font-size:1rem}#game-title{text-align:center;margin-top:.5rem}#tiles,#operators{grid-template-columns:repeat(4,1fr);gap:.75rem;display:grid}#tiles{margin-top:1.5rem}#operators{margin-top:.75rem}#tiles button{min-height:4rem;font-size:1.6rem;font-weight:600}#operators button{min-height:3rem;font-size:1.3rem}#tiles button,#operators button,#controls button{cursor:pointer;background:#eef1f7;border:none;border-radius:.75rem}#tiles button:disabled,#operators button:disabled,#controls button:disabled{opacity:.4;cursor:not-allowed}#tiles button.used{background:#dcdfe6;text-decoration:line-through}#current-value{text-align:center;font-variant-numeric:tabular-nums;min-height:2.5rem;margin:1.5rem 0 .5rem;font-size:2rem;font-weight:700}#history{text-align:center;font-variant-numeric:tabular-nums;color:#6a6a6a;flex-direction:column;gap:.25rem;margin:0 0 1.5rem;padding:0;font-size:.95rem;list-style:none;display:flex}#controls{grid-template-columns:repeat(4,1fr);gap:.5rem;margin-top:1rem;display:grid}#controls button{min-height:3rem;padding:0 .25rem;font-size:1rem}#controls button#submit{color:#fff;background:#0b5fff;font-weight:600}#move-error{text-align:center;color:#b3261e;min-height:1.2rem;margin:.5rem 0 0;font-size:.9rem;font-weight:600}#feedback{margin-top:1.5rem}#feedback .feedback-message{margin:0 0 .75rem;font-size:1.1rem;font-weight:600}#feedback .feedback-message.failure{color:#b3261e}#feedback .feedback-message.success{color:#1f9d55}#feedback button{color:#fff;cursor:pointer;background:#0b5fff;border:none;border-radius:.5rem;min-height:2.75rem;margin:0 .5rem .5rem 0;padding:0 1.25rem}#congrats{text-align:center;background:#fff;border:1px solid #e6e6e6;border-radius:1rem;padding:2.5rem;box-shadow:0 8px 24px #0000000f}#congrats h2{color:#1f9d55;margin-top:0;font-size:1.75rem}#congrats-controls{grid-template-columns:repeat(2,1fr);gap:.75rem;margin-top:1.5rem;display:grid}#congrats-controls button{cursor:pointer;border:none;border-radius:.75rem;min-height:3rem;font-size:1rem}#congrats-play-again{color:#fff;background:#0b5fff;font-weight:600}#congrats-back{background:#eef1f7}@media (width<=480px){body{padding:1rem .75rem}#game,#congrats{box-shadow:none;border:none;border-radius:0;padding:0}#tiles button{min-height:3.5rem;font-size:1.3rem}#operators button{min-height:3rem;font-size:1.15rem}#controls{gap:.4rem}#controls button{min-height:3rem;padding:0 .15rem;font-size:.85rem}#current-value{font-size:1.6rem}}