:root {
    --bg-color: #f4f4f4;
    --text-color: #333;
    --container-bg: #fff;
    --heading-color: #0056b3;
    --border-color: #ccc;
    --button-bg: #007bff;
    --button-hover-bg: #0056b3;
    --numbers-color: #28a745;
}

body.dark-mode {
    --bg-color: #2c2c2c;
    --text-color: #e0e0e0;
    --container-bg: #3c3c3c;
    --heading-color: #6daffb;
    --border-color: #555;
    --button-bg: #4a90e2;
    --button-hover-bg: #357ABD;
    --numbers-color: #8ed28e;
}

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

.container {
    background-color: var(--container-bg);
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    text-align: center;
    width: 90%;
    max-width: 500px;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

h1 {
    color: var(--heading-color);
    margin-bottom: 20px;
    transition: color 0.3s ease;
}

.numbers-display {
    margin: 20px 0;
    padding: 15px;
    border: 2px dashed var(--border-color);
    border-radius: 5px;
    min-height: 50px;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    font-size: 1.8em;
    font-weight: bold;
    color: var(--numbers-color);
    transition: border-color 0.3s ease, color 0.3s ease;
}

.numbers-display span {
    margin: 0 8px;
}

button {
    background-color: var(--button-bg);
    color: white;
    padding: 12px 25px;
    border: none;
    border-radius: 5px;
    font-size: 1.1em;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

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

/* Theme toggle button specific styles */
.theme-toggle {
    position: absolute;
    top: 20px;
    right: 20px;
    background-color: transparent;
    border: 1px solid var(--border-color);
    font-size: 1.5em;
    cursor: pointer;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--text-color);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.theme-toggle:hover {
    background-color: rgba(0,0,0,0.05);
}

body.dark-mode .theme-toggle {
    border-color: var(--border-color);
    color: var(--text-color);
    background-color: rgba(255,255,255,0.05);
}

body.dark-mode .theme-toggle:hover {
    background-color: rgba(255,255,255,0.1);
}