body {
    --page-bg: #f0f2f5;
    --panel-bg: #ffffff;
    --text-color: #333333;
    --muted-text: #5f6673;
    --heading-color: #1877f2;
    --primary-bg: #1877f2;
    --primary-hover-bg: #166fe5;
    --ball-bg: #4CAF50;
    --field-bg: #ffffff;
    --field-border: #cfd7e3;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --button-shadow: rgba(0, 0, 0, 0.2);

    font-family: sans-serif;
    background-color: var(--page-bg);
    color: var(--text-color);
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 40px 20px;
    box-sizing: border-box;
    transition: background-color 0.3s, color 0.3s;
}

body.dark-mode {
    --page-bg: #111827;
    --panel-bg: #1f2937;
    --text-color: #f9fafb;
    --muted-text: #cbd5e1;
    --heading-color: #60a5fa;
    --primary-bg: #2563eb;
    --primary-hover-bg: #1d4ed8;
    --ball-bg: #16a34a;
    --field-bg: #111827;
    --field-border: #4b5563;
    --shadow-color: rgba(0, 0, 0, 0.35);
    --button-shadow: rgba(0, 0, 0, 0.35);
}

.container {
    background-color: var(--panel-bg);
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 4px 20px var(--shadow-color);
    text-align: center;
    width: min(100%, 760px);
    transition: background-color 0.3s, box-shadow 0.3s;
}

h1,
h2 {
    color: var(--heading-color);
}

h1 {
    font-size: 2.5em;
    margin-bottom: 20px;
}

h2 {
    font-size: 1.6em;
    margin: 0 0 20px;
}

.numbers-container {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-bottom: 30px;
}

.number {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.8em;
    font-weight: bold;
    color: white;
    background-color: var(--ball-bg);
    box-shadow: 0 2px 5px var(--button-shadow);
    transition: background-color 0.3s, box-shadow 0.3s;
}

button {
    padding: 15px 35px;
    font-size: 1.2em;
    border: none;
    border-radius: 8px;
    background-color: var(--primary-bg);
    color: white;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.2s;
    box-shadow: 0 2px 5px var(--button-shadow);
}

button:hover {
    background-color: var(--primary-hover-bg);
    transform: translateY(-2px);
}

.theme-toggle {
    display: block;
    margin-left: auto;
    margin-bottom: 24px;
    padding: 10px 18px;
    font-size: 0.95em;
}

.contact-section {
    border-top: 1px solid var(--field-border);
    margin-top: 40px;
    padding-top: 32px;
    text-align: left;
}

.contact-form {
    display: grid;
    gap: 18px;
}

.form-grid {
    display: grid;
    gap: 18px;
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.contact-form label {
    color: var(--muted-text);
    display: grid;
    font-size: 0.95em;
    font-weight: 700;
    gap: 8px;
}

.contact-form input,
.contact-form textarea {
    background-color: var(--field-bg);
    border: 1px solid var(--field-border);
    border-radius: 8px;
    box-sizing: border-box;
    color: var(--text-color);
    font: inherit;
    padding: 12px 14px;
    transition: border-color 0.2s, box-shadow 0.2s, background-color 0.3s, color 0.3s;
    width: 100%;
}

.contact-form textarea {
    resize: vertical;
}

.contact-form input:focus,
.contact-form textarea:focus {
    border-color: var(--primary-bg);
    box-shadow: 0 0 0 3px rgba(24, 119, 242, 0.16);
    outline: none;
}

.contact-form button {
    justify-self: end;
}

@media (max-width: 640px) {
    body {
        padding: 20px;
    }

    .container {
        width: 100%;
        padding: 28px 20px;
    }

    h1 {
        font-size: 2em;
    }

    .numbers-container {
        flex-wrap: wrap;
    }

    .form-grid {
        grid-template-columns: 1fr;
    }

    .contact-form button {
        justify-self: stretch;
    }
}