* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Arial', sans-serif;
}

body {
    background-color: #f5f9fa;
    color: #333;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 20px;
    text-align: center;
}

header {
    margin-bottom: 20px;
}

h1 {
    color: #ff6f00;
    margin-bottom: 15px;
}

.score-container {
    display: flex;
    justify-content: space-around;
    margin: 15px 0;
    font-size: 1.2em;
    font-weight: bold;
}

.instructions {
    font-size: 1.5em;
    background-color: #fff;
    padding: 10px;
    border-radius: 10px;
    margin: 15px auto;
    width: fit-content;
    min-width: 300px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.home-button {
    display: inline-block;
    margin: 10px;
    padding: 8px 16px;
    background-color: #ff6f00;
    color: white;
    text-decoration: none;
    border-radius: 5px;
    transition: background-color 0.3s;
}

.home-button:hover {
    background-color: #e65100;
}

#game-container {
    position: relative;
    width: 100%;
    height: 500px;
    background-color: #fff3e0;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 6px 12px rgba(0,0,0,0.1);
}

#start-screen, #game-over {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background-color: rgba(255, 255, 255, 0.9);
    z-index: 10;
}

#game-area {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: space-around;
    align-items: center;
    padding: 20px;
}

#equation-container {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px;
    margin: 20px 0;
    font-size: 2.5em;
    font-weight: bold;
}

.equation-part {
    padding: 15px;
    border-radius: 10px;
    background-color: #fff;
    min-width: 60px;
    height: 80px;
    display: flex;
    justify-content: center;
    align-items: center;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.equation-part.operator {
    background-color: transparent;
    box-shadow: none;
}

.equation-part.missing {
    background-color: #ffecb3;
    border: 2px dashed #ff6f00;
}

.equation-part.drop-target {
    background-color: #ffe082;
    border: 2px solid #ff6f00;
}

#numbers-container {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 15px;
    margin: 20px 0;
}

.number-option {
    width: 70px;
    height: 70px;
    background: linear-gradient(135deg, #ff9800, #ff6f00);
    color: white;
    font-size: 1.8em;
    font-weight: bold;
    border-radius: 10px;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: move;
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
    transition: transform 0.2s;
}

.number-option:hover {
    transform: scale(1.05);
}

.number-option.dragging {
    opacity: 0.7;
    transform: scale(1.1);
}

#feedback-container {
    height: 60px;
    margin: 20px 0;
    font-size: 1.8em;
    font-weight: bold;
}

.feedback-message {
    padding: 10px 25px;
    border-radius: 10px;
    display: inline-block;
    animation: fadeInOut 2s forwards;
}

.feedback-message.correct {
    background-color: #a5d6a7;
    color: #2e7d32;
}

.feedback-message.wrong {
    background-color: #ef9a9a;
    color: #c62828;
}

@keyframes fadeInOut {
    0% { opacity: 0; }
    20% { opacity: 1; }
    80% { opacity: 1; }
    100% { opacity: 0; }
}

.bonus-time-notification {
    position: absolute;
    top: 60px;
    right: 20px;
    background-color: #4caf50;
    color: white;
    padding: 8px 12px;
    border-radius: 20px;
    font-weight: bold;
    animation: bonusTime 2s ease-in-out;
    z-index: 10;
}

@keyframes bonusTime {
    0% { opacity: 0; transform: translateY(20px); }
    20% { opacity: 1; transform: translateY(0); }
    80% { opacity: 1; }
    100% { opacity: 0; transform: translateY(-20px); }
}

button {
    padding: 12px 25px;
    margin: 15px 0;
    background-color: #ff6f00;
    color: white;
    border: none;
    border-radius: 5px;
    font-size: 1.1em;
    cursor: pointer;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #e65100;
}

.hidden {
    display: none !important;
}

.correct-animation {
    animation: correctFlash 0.5s;
}

@keyframes correctFlash {
    0% { background-color: #ffecb3; }
    50% { background-color: #a5d6a7; }
    100% { background-color: #ffecb3; }
}

.wrong-animation {
    animation: wrongShake 0.5s;
}

@keyframes wrongShake {
    0% { transform: translateX(0); }
    20% { transform: translateX(-10px); }
    40% { transform: translateX(10px); }
    60% { transform: translateX(-5px); }
    80% { transform: translateX(5px); }
    100% { transform: translateX(0); }
}