:root {
    --background-color: #f0f0f0;
    --container-background: white;
    --text-color: #333;
    --h2-color: #555;
    --border-color: #eee;
    --input-border-color: #ccc;
    --button-bg-color: #4CAF50;
    --button-text-color: white;
    --button-hover-bg-color: #45a049;
    --toggle-button-bg-color: #ddd;
    --toggle-button-text-color: #333;
}

[data-theme='dark'] {
    --background-color: #121212;
    --container-background: #1e1e1e;
    --text-color: #e0e0e0;
    --h2-color: #c7c7c7;
    --border-color: #333;
    --input-border-color: #555;
    --button-bg-color: #5a5a5a;
    --button-text-color: #e0e0e0;
    --button-hover-bg-color: #6a6a6a;
    --toggle-button-bg-color: #555;
    --toggle-button-text-color: #e0e0e0;
}

body {
    font-family: sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    transition: background-color 0.3s, color 0.3s;
}

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

h1 {
    color: var(--text-color);
}

h2 {
    color: var(--h2-color);
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
    margin-top: 1.5rem;
}

.numbers-container, .number-inputs {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 1rem;
}

.number, .number-inputs input {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.2rem;
    font-weight: bold;
}

.number-inputs input {
    border: 2px solid var(--input-border-color);
    text-align: center;
    background-color: var(--container-background);
    color: var(--text-color);
    -moz-appearance: textfield; /* Firefox */
}

.number-inputs input::-webkit-outer-spin-button,
.number-inputs input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

#check-button {
    background-color: var(--button-bg-color);
    color: var(--button-text-color);
    border: none;
    padding: 0.8rem 1.5rem;
    font-size: 1rem;
    border-radius: 5px;
    cursor: pointer;
    margin-top: 1.5rem;
    transition: background-color 0.3s;
}

#check-button:hover {
    background-color: var(--button-hover-bg-color);
}

#theme-toggle {
    background-color: var(--toggle-button-bg-color);
    color: var(--toggle-button-text-color);
    border: 1px solid var(--input-border-color);
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
    border-radius: 5px;
    cursor: pointer;
    margin-bottom: 1rem;
    transition: background-color 0.3s, color 0.3s;
}

.result {
    margin-top: 1.5rem;
}

#result-text {
    font-size: 1.1rem;
    font-weight: bold;
}