* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-size: 16px;
    font-family: Arial, Helvetica, sans-serif;
    background-color: #f5f5f5;
}

.container {
    max-width: 1100px;
}

.header {
    background-color: #222;
    color: white;
    padding: 60px 0;
    text-align: center;
}

.header__title {
    font-size: 2rem;
}

.header__subtitle {
    font-size: 1.1rem;
}

.section__title {
    font-size: 1.6rem;
    margin-bottom: 20px;
}

.about {
    padding: 60px 0;
    text-align: center;
}

.btn {
    padding: 12px 24px;
    font-size: 1rem;
    background-color: #222;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}

.btn:hover {
    background-color: #444;
}

.btn:disabled {
    background-color: #888;
    cursor: not-allowed;
}

.btn {
    transition: background-color 0.3s ease;
}

.message {
    margin-top: 20px;
    font-weight: bold;
    color: #222;
}

footer {
    background-color: #ddd;
    text-align: center;
    padding: 20px 0;
}


/* Tablets */

@media (min-width:768px) {
    .header__title {
        font-size: 2.5rem;
    }

    .about__text {
        max-width: 700px;
        margin: 0 auto;
    }
}

/* Desktop */

@media (min-width:1024px) {
    .header {
        padding: 100px 0;
    }

    .section__title {
        font-size: 2rem;
    }
}