:root{--bg-color: #f9f9f9;--text-color: #333;--primary-color: #3b82f6;--success-color: #22c55e;--error-color: #9ca3af;--correction-color: #f97316;--bar-bg: #e5e7eb;--bar-fill: #22c55e;--font-main: "Fredoka", sans-serif;--font-mono: "Roboto Mono", monospace}*{box-sizing:border-box;margin:0;padding:0}body{font-family:var(--font-main);background-color:var(--bg-color);color:var(--text-color);height:100vh;overflow:hidden;display:flex;flex-direction:column}#app{width:100%;height:100%;position:relative;display:flex;flex-direction:column;z-index:1}.screen{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;width:100%;height:100%;padding:20px}.hidden{display:none!important}#start-screen h1{font-size:3rem;margin-bottom:2rem;color:var(--primary-color)}.config-container{background:#fff;padding:2rem;border-radius:1rem;box-shadow:0 4px 6px -1px #0000001a;display:flex;flex-direction:column;gap:1.5rem;width:100%;max-width:400px}.input-group{display:flex;flex-direction:column;gap:.5rem}.input-group label{font-weight:500}.input-group input{padding:.75rem;border:2px solid #e5e7eb;border-radius:.5rem;font-size:1.2rem;font-family:var(--font-mono);text-align:center}.primary-btn{background-color:var(--primary-color);color:#fff;border:none;padding:.75rem 1.5rem;border-radius:.5rem;font-size:1.2rem;font-weight:600;cursor:pointer;transition:background-color .2s;font-family:var(--font-main)}.primary-btn:hover{background-color:#2563eb}.icon-btn{background-color:var(--primary-color);color:#fff;border:none;width:48px;height:48px;border-radius:50%;display:flex;align-items:center;justify-content:center;cursor:pointer;transition:transform .1s;box-shadow:0 2px 4px #0000001a}.icon-btn:active{transform:scale(.95)}.avatar-selector{text-align:center;margin-bottom:1rem}.avatar-selector p{margin-bottom:.5rem;font-weight:500}.avatars{display:flex;justify-content:center;gap:.5rem;flex-wrap:wrap}.avatar-option{font-size:2rem;cursor:pointer;padding:.5rem;border:2px solid transparent;border-radius:50%;transition:all .2s;-webkit-user-select:none;user-select:none}.avatar-option:hover{transform:scale(1.1);background-color:#f3f4f6}.avatar-option.selected{background-color:#dbeafe;border-color:var(--primary-color);transform:scale(1.1)}#game-screen{justify-content:flex-start;padding:0}.top-bar{width:100%;padding:1rem;display:flex;flex-direction:column;gap:1rem;background:#fff;box-shadow:0 1px 2px #0000000d;z-index:10}.progress-container{width:100%;height:24px;background-color:var(--bar-bg);border-radius:12px;overflow:hidden;position:relative}.progress-bar{height:100%;background-color:var(--bar-fill);width:0%;transition:width .3s ease-out}.controls{display:flex;justify-content:space-between;width:100%;padding:0 1rem}.game-content{flex:1;display:flex;flex-direction:column;justify-content:center;align-items:center;width:100%;max-width:600px;margin:0 auto;position:relative}.history-container{display:flex;flex-direction:column-reverse;align-items:center;width:100%;margin-bottom:2rem;height:150px;overflow:hidden;position:relative}.history-item{font-size:2rem;margin:.5rem 0;font-family:var(--font-mono);transition:all .5s ease;opacity:1;display:grid;grid-template-columns:1fr auto 1fr;gap:1rem;width:100%;align-items:center}.lhs{text-align:right}.eq{text-align:center}.rhs{text-align:left;display:flex;align-items:center;gap:.5rem}.history-item.correct{color:var(--text-color)}.history-item.correct .answer{color:var(--success-color);text-decoration:underline;font-weight:700}.history-item.incorrect{color:var(--text-color)}.history-item.incorrect .answer{color:var(--error-color);text-decoration:line-through}.history-item.incorrect .correction{color:#eab308;font-weight:700;margin-left:.5rem}.ok-sign{color:var(--success-color);font-size:1rem;font-weight:700;margin-left:.5rem}.history-item:nth-child(1){opacity:1;transform:scale(1)}.history-item:nth-child(2){opacity:.6;transform:scale(.95)}.history-item:nth-child(3){opacity:.3;transform:scale(.9)}.history-item:nth-child(n+4){opacity:0}.current-problem-container{display:flex;align-items:center;justify-content:center;gap:1rem;font-size:3rem;font-family:var(--font-mono);margin-bottom:10vh}.problem-display{display:flex;align-items:center;gap:.5rem}#answer-input{width:120px;height:80px;font-size:3rem;text-align:center;border:3px solid black;border-radius:8px;font-family:var(--font-mono);background:#fff}#answer-input:focus{outline:none;border-color:var(--primary-color)}#answer-input:read-only{background-color:#fff;cursor:default}#answer-input::-webkit-outer-spin-button,#answer-input::-webkit-inner-spin-button{-webkit-appearance:none;margin:0}#answer-input[type=number]{-moz-appearance:textfield;-webkit-appearance:textfield;appearance:textfield}.overlay{position:fixed;top:0;left:0;width:100%;height:100%;background:#fffffff2;z-index:100;display:flex;justify-content:center;align-items:center}.overlay-content{background:#fff;padding:2rem;border-radius:1rem;box-shadow:0 10px 25px #0000001a;width:fit-content;max-width:90%;max-height:90vh;display:flex;flex-direction:column;position:relative}.overlay-header{display:flex;justify-content:center;align-items:center;margin-bottom:1rem}#close-stats-btn{position:absolute;top:1rem;right:1rem}.stats-grid{display:grid;gap:4px;overflow-y:auto;padding:4px;max-width:450px;margin:0 auto}.stat-cell{aspect-ratio:1;display:flex;align-items:center;justify-content:center;font-size:.8rem;border-radius:4px;background:#eee;color:#555;font-weight:700;position:relative}.stat-cell.good{background-color:#dcfce7;color:#166534}.stat-cell.bad{background-color:#fee2e2;color:#991b1b}.stat-cell.mixed{background-color:#fef3c7;color:#92400e}.stat-cell.empty{background-color:#f3f4f6;color:#d1d5db}#congrats-screen{text-align:center}#congrats-screen h1{font-size:4rem;color:var(--success-color);margin-bottom:1rem}#congrats-screen p{font-size:1.5rem;margin-bottom:2rem}#turtle-container{position:fixed;top:0;left:0;width:100%;height:100%;pointer-events:none;z-index:0;overflow:hidden}.turtle{position:absolute;font-size:2rem;opacity:0;animation:turtle-pop-in .5s cubic-bezier(.175,.885,.32,1.275) forwards;filter:drop-shadow(0 2px 4px rgba(0,0,0,.1))}@keyframes turtle-pop-in{0%{opacity:0;transform:scale(0) rotate(-10deg)}to{opacity:.6;transform:scale(1) rotate(0)}}.virtual-keypad{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;width:100%;max-width:300px;margin-top:2rem}.key{background:#fff;border:2px solid #e5e7eb;border-radius:12px;padding:15px;font-size:1.5rem;font-family:var(--font-mono);font-weight:700;color:var(--text-color);cursor:pointer;transition:all .1s;touch-action:manipulation;-webkit-user-select:none;user-select:none;-webkit-tap-highlight-color:transparent}.key:active{background-color:#f3f4f6;transform:scale(.95)}.key.action-key{background-color:#eff6ff;color:var(--primary-color);border-color:#bfdbfe}.key.action-key:active{background-color:#dbeafe}@media (max-width: 600px){.virtual-keypad{margin-top:1rem;gap:8px}.key{padding:12px;font-size:1.25rem}.game-content{justify-content:flex-start;padding-top:1rem}.history-container{height:100px;margin-bottom:1rem}.current-problem-container{margin-bottom:1rem}}@media (max-height: 700px){.history-container{height:80px;margin-bottom:.5rem}.history-item{font-size:1.5rem;margin:.25rem 0}.current-problem-container{margin-bottom:.5rem;font-size:2rem}#answer-input{height:50px;width:80px;font-size:2rem}.virtual-keypad{margin-top:.5rem;gap:6px}.key{padding:8px}}@media (max-width: 600px){.current-problem-container{font-size:2rem;flex-direction:column}#answer-input{width:100px;height:60px;font-size:2rem}.history-item{font-size:1.5rem}}