:root {
    --bg-color: #f0f2f5;
    --container-bg: white;
    --text-color: #333;
    --ball-empty-bg: #ccc;
    --btn-bg: #4a90e2;
    --btn-hover: #357abd;
}

[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --container-bg: #2d2d2d;
    --text-color: #f0f2f5;
    --ball-empty-bg: #444;
    --btn-bg: #357abd;
    --btn-hover: #4a90e2;
}

body {
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    text-align: center;
    background: var(--container-bg);
    padding: 2rem;
    border-radius: 20px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    transition: background-color 0.3s ease;
    position: relative;
}

h1 {
    margin-bottom: 2rem;
}

.numbers-container {
    display: flex;
    gap: 15px;
    margin-bottom: 2rem;
    justify-content: center;
}

.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: var(--ball-empty-bg);
    transition: transform 0.3s ease, background-color 0.3s ease;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

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

button {
    padding: 12px 30px;
    font-size: 1.1rem;
    cursor: pointer;
    background-color: var(--btn-bg);
    color: white;
    border: none;
    border-radius: 10px;
    transition: background-color 0.2s, transform 0.1s;
}

button:hover {
    background-color: var(--btn-hover);
}

button:active {
    transform: translateY(2px);
}

/* Theme Switch Styles */
.theme-switch-wrapper {
    display: flex;
    align-items: center;
    justify-content: flex-end;
    margin-bottom: 1rem;
}

#theme-text {
    margin-left: 10px;
    font-size: 0.9rem;
}

.theme-switch {
    display: inline-block;
    height: 24px;
    position: relative;
    width: 44px;
}

.theme-switch input {
    display: none;
}

.slider {
    background-color: #ccc;
    bottom: 0;
    cursor: pointer;
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    transition: .4s;
}

.slider:before {
    background-color: #fff;
    bottom: 4px;
    content: "";
    height: 16px;
    left: 4px;
    position: absolute;
    transition: .4s;
    width: 16px;
}

input:checked + .slider {
    background-color: #4a90e2;
}

input:checked + .slider:before {
    transform: translateX(20px);
}

.slider.round {
    border-radius: 34px;
}

.slider.round:before {
    border-radius: 50%;
}