body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--tg-theme-bg-color, #ffffff);
    color: var(--tg-theme-text-color, #000000);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    margin: 0;
    text-align: center;
}
.container {
    padding: 20px;
}
h1 { font-size: 48px; margin-bottom: 10px; }
p { font-size: 18px; color: var(--tg-theme-hint-color, #999); }
.back-button {
    margin-top: 30px;
    padding: 12px 24px;
    background-color: var(--tg-theme-button-color, #3390ec);
    color: var(--tg-theme-button-text-color, #ffffff);
    border: none;
    border-radius: 12px;
    text-decoration: none;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
}