body {
    font-family: sans-serif;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f0f0f0;
    margin: 0;
}

.container {
    text-align: center;
    background-color: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

h1 {
    margin-bottom: 1.5rem;
}

.numbers-container {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 1.5rem;
    min-height: 50px;
}

.number {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    /* background-color: #4CAF50; */ /* 색상은 JS에서 동적으로 할당 */
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.2rem;
    font-weight: bold;
    animation: pop-in 0.5s cubic-bezier(0.68, -0.55, 0.27, 1.55) forwards;
}

.history-container {
    margin-top: 2rem;
    text-align: center;
}

.history-entry {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
    color: #555;
}

@keyframes pop-in {
    0% {
        transform: scale(0);
        opacity: 0;
    }
    100% {
        transform: scale(1);
        opacity: 1;
    }
}

.container.shaking {
    animation: shake 0.5s linear;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-2px); }
    75% { transform: translateX(2px); }
}

#generate-btn {
    padding: 10px 20px;
    font-size: 1rem;
    border: none;
    border-radius: 5px;
    background-color: #008CBA;
    color: white;
    cursor: pointer;
    transition: background-color 0.3s;
}

#generate-btn:hover {
    background-color: #005f7a;
}