body {
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
    background-color: #f0f2f5;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.container {
    background-color: white;
    padding: 2rem;
    border-radius: 20px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    text-align: center;
    width: 90%;
    max-width: 500px;
}

h1 {
    color: #333;
    margin-bottom: 2rem;
}

.numbers-container {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.ball {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-weight: bold;
    font-size: 1.2rem;
    color: white;
    background-color: #ccc;
    box-shadow: inset -3px -3px 5px rgba(0,0,0,0.2);
    transition: transform 0.3s ease;
}

.ball.active {
    transform: scale(1.1);
}

#generate-btn {
    background-color: #4a90e2;
    color: white;
    border: none;
    padding: 1rem 2rem;
    font-size: 1.1rem;
    border-radius: 10px;
    cursor: pointer;
    transition: background-color 0.2s;
    width: 100%;
}

#generate-btn:hover {
    background-color: #357abd;
}

#generate-btn:active {
    transform: translateY(2px);
}

/* Ball Colors */
.n1-10 { background-color: #fbc400; } /* Yellow */
.n11-20 { background-color: #69c8f2; } /* Blue */
.n21-30 { background-color: #ff7272; } /* Red */
.n31-40 { background-color: #aaaaaa; } /* Gray */
.n41-45 { background-color: #b0d840; } /* Green */