:root {
    --bg-color: #f0f4ff;
    --text-color: #333;
    --header-bg: #4a76f7;
    --header-text: white;
    --btn-bg: #4a76f7;
    --btn-hover: #345de2;
    --ball-bg: #fff;
    --ball-border: #4a76f7;
    --ball-text: #333;
    --container-bg: transparent;
}

[data-theme="dark"] {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --header-bg: #1f1f1f;
    --header-text: #ffffff;
    --btn-bg: #3700b3;
    --btn-hover: #6200ee;
    --ball-bg: #1e1e1e;
    --ball-border: #bb86fc;
    --ball-text: #ffffff;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    text-align: center;
    margin: 0;
    padding: 0;
    transition: background-color 0.3s, color 0.3s;
}

header {
    background-color: var(--header-bg);
    color: var(--header-text);
    padding: 25px;
    font-size: 24px;
    font-weight: bold;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 40px;
}

#container {
    margin-top: 40px;
    padding: 20px;
}

#btn {
    background-color: var(--btn-bg);
    color: white;
    border: none;
    padding: 15px 30px;
    font-size: 18px;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s;
}

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

.set {
    margin-top: 30px;
    padding: 15px;
}

.ball {
    display: inline-block;
    width: 45px;
    height: 45px;
    line-height: 45px;
    margin: 5px;
    border-radius: 50%;
    background-color: var(--ball-bg);
    border: 2px solid var(--ball-border);
    color: var(--ball-text);
    font-size: 20px;
    font-weight: bold;
    transition: background-color 0.3s, border-color 0.3s, color 0.3s;
}

#theme-toggle {
    background: none;
    border: 1px solid var(--header-text);
    color: var(--header-text);
    padding: 8px 16px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.3s;
}

#theme-toggle:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

#contact-section {
    margin: 50px auto;
    padding: 30px;
    max-width: 500px;
    background-color: var(--ball-bg);
    border: 1px solid var(--ball-border);
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

#contact-form {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

#contact-form input, #contact-form textarea {
    padding: 12px;
    border: 1px solid var(--ball-border);
    border-radius: 6px;
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: inherit;
}

#contact-form textarea {
    height: 100px;
    resize: vertical;
}

#contact-form button {
    background-color: var(--btn-bg);
    color: white;
    border: none;
    padding: 12px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: bold;
    transition: background-color 0.3s;
}

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