/* Operator Quiz Styles */
:root {
    --bg-color: #F8F3E6; /* Wall color */
    --board-color: #2F4F4F; /* Blackboard Green */
    --chalk-color: #FFF;
    --wood-color: #8D6E63;
}

body {
    margin: 0;
    padding: 0;
    font-family: 'Roboto', sans-serif;
    background-color: var(--bg-color);
    background-image: 
        linear-gradient(90deg, rgba(200,200,200,.1) 50%, transparent 50%),
        linear-gradient(rgba(200,200,200,.1) 50%, transparent 50%);
    background-size: 50px 50px;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    user-select: none;
}

.home-btn {
    position: absolute;
    top: 20px; left: 20px;
    font-size: 1.5rem;
    color: #555;
    background: #fff;
    width: 40px; height: 40px;
    border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    text-decoration: none;
    z-index: 100;
}

.game-container {
    width: 90%;
    max-width: 800px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
}

.blackboard {
    background-color: var(--board-color);
    width: 100%;
    padding: 20px;
    border: 15px solid var(--wood-color);
    border-radius: 10px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.3);
    position: relative;
    min-height: 300px;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.header-info {
    position: absolute;
    top: 15px; left: 20px; right: 20px;
    display: flex;
    justify-content: space-between;
    font-family: 'Courier New', monospace;
    color: rgba(255,255,255,0.7);
    font-weight: bold;
    font-size: 1.2rem;
}

.equation-area {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    font-family: 'Fredericka the Great', cursive; /* Chalk font */
    color: var(--chalk-color);
    font-size: 4rem; /* Big */
    text-shadow: 2px 2px 4px rgba(0,0,0,0.5);
    flex-wrap: wrap;
}

.operator-box {
    width: 80px; height: 80px;
    border: 3px dashed rgba(255,255,255,0.5);
    border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    color: #FFD54F; /* Highlight color for missing op */
}

/* Controls */
.controls-area {
    display: flex;
    gap: 20px;
    margin-top: 20px;
}

.op-btn {
    width: 80px; height: 80px;
    border: none;
    border-radius: 50%;
    font-size: 2.5rem;
    color: #fff;
    cursor: pointer;
    box-shadow: 0 5px 0 rgba(0,0,0,0.2);
    transition: transform 0.1s;
    display: flex; align-items: center; justify-content: center;
}
.op-btn:nth-child(1) { background: #4CAF50; } /* + */
.op-btn:nth-child(2) { background: #2196F3; } /* - */
.op-btn:nth-child(3) { background: #FF9800; } /* * */
.op-btn:nth-child(4) { background: #F44336; } /* / */

.op-btn:active {
    transform: translateY(5px);
    box-shadow: none;
}

@media (max-width: 600px) {
    .equation-area { font-size: 2.5rem; gap: 10px; }
    .operator-box, .op-btn { width: 60px; height: 60px; font-size: 2rem; }
    .blackboard { min-height: 200px; }
}

/* Modals */
.modal-overlay {
    position: fixed; top: 0; left: 0; width: 100%; height: 100%;
    background: rgba(0,0,0,0.7);
    display: flex; align-items: center; justify-content: center;
    z-index: 1000;
}
.modal-content {
    background: #fff;
    padding: 30px;
    border-radius: 20px;
    text-align: center;
    min-width: 300px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
}
.modal-content h2 { margin-top: 0; color: #333; }
.btn-control {
    padding: 10px 20px;
    background: #4CAF50;
    border: none;
    color: #fff;
    border-radius: 20px;
    font-size: 1.1rem;
    cursor: pointer;
    margin-top: 15px;
}