:root {
    --bg-color: #f0f2f5;
    --surface-color: #ffffff;
    --text-color: #333333;
    --primary-color: #4a90e2;
    --primary-hover-color: #357abd;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

body.dark-mode {
    --bg-color: #14181f;
    --surface-color: #1f2633;
    --text-color: #e8edf5;
    --primary-color: #5ba1f0;
    --primary-hover-color: #3f86d6;
    --shadow-color: rgba(0, 0, 0, 0.35);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    padding: 1rem;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.25s ease, color 0.25s ease;
}

#app {
    text-align: center;
    width: 100%;
    max-width: 520px;
    background-color: var(--surface-color);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 6px var(--shadow-color);
    transition: background-color 0.25s ease, box-shadow 0.25s ease;
}

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

#numbers {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin: 2rem 0;
}

.number {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: var(--primary-color);
    color: white;
    font-size: 1.5rem;
    font-weight: bold;
    animation: fadeIn 0.5s ease-in-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: scale(0.5);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 20px;
    font-size: 1rem;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

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

#theme-toggle {
    margin-bottom: 1rem;
}

#partnership {
    margin-top: 2rem;
    text-align: left;
}

#partnership h2 {
    margin: 0 0 0.75rem;
    color: var(--text-color);
    font-size: 1.1rem;
}

#partnership form {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

#partnership label {
    font-size: 0.9rem;
    font-weight: 600;
}

#partnership input,
#partnership textarea {
    padding: 0.65rem 0.7rem;
    border: 1px solid rgba(127, 127, 127, 0.35);
    border-radius: 6px;
    font-size: 0.95rem;
    font-family: inherit;
    color: var(--text-color);
    background-color: var(--surface-color);
}

#partnership textarea {
    resize: vertical;
}