:root {
    --mau-chinh: #12305f;
    --mau-chinh-dam: #0a1f40;
    --mau-nhan: #e65100;
    --mau-nhan-dam: #bf360c;
    --mau-zalo: #0068ff;
    --mau-zalo-dam: #0050c8;
    --mau-nen: #f4f5f7;
    --mau-chu: #222;
    --mau-chu-phu: #555;
}

body {
    background-color: var(--mau-nen);
    font-family: 'Be Vietnam Pro', sans-serif;
    font-size: 17px;
    margin: 0;
    color: var(--mau-chu);
}

header {
    text-align: center;
    background-color: var(--mau-chinh);
    padding: 16px;
    color: white;
}

h1 {
    font-size: 26px;
}

img {
    width: 100%;
    border-radius: 10px;
}

nav a {
    color: white;
    text-decoration: none;
    padding: 12px;
    border: 1px solid white;
    font-size: 15px;
    font-weight: bold;
    transition: 0.3s;
    display: inline-block;
    margin: 4px;
}

main {
    padding: 20px;
    max-width: 1000px;
    margin: 0 auto;
}

footer {
    padding: 20px;
    background-color: var(--mau-chinh);
    text-align: center;
    color: white;
    font-size: 20px;
    padding-bottom: 120px;

}

header p {
    font-size: 23px;
    font-weight: bold;
}

.luoi-anh {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

.luoi-anh img {
    aspect-ratio: 2 / 3;
    object-fit: cover;
    object-position: center;
}

.nut-goi {
    padding: 8px;
    background-color: var(--mau-nhan);
    font-weight: bold;
    border-radius: 5px;
    font-size: 20px;
    color: white;
    text-decoration: none;
    display: inline-block;
    margin: 0;
    transition: 0.3s;

}

.nut-zalo {
    background-color: var(--mau-zalo);
}

.nut-goi:hover {
    background-color: var(--mau-nhan-dam);
}

.nut-zalo:hover {
    background-color: var(--mau-zalo-dam);
}

.khau-hieu {
    font-size: 17px;
}

@media (min-width: 900px) {
    .luoi-anh {
        grid-template-columns: 1fr 1fr 1fr;

    }

    h1 {
        font-size: 50px;
    }

    .khau-hieu {
        font-size: 25px;
    }
    }


    nav a:hover {
        color: var(--mau-nhan);
    }



    iframe {
        width: 100%;
        height: 350px;
        border: 0;
        border-radius: 10px;
    }

    .ban-quyen {
        font-size: 14px;
    }

    .nut-chi-duong {
        background-color: var(--mau-chinh);
    }

    .nut-chi-duong:hover {
        background-color: Var(--mau-chinh-dam);
    }

    figure {
        margin: 0;
    }

    figcaption {
        padding-top: 8px;

        color: var(--mau-chu-phu);
        font-size: 15px;
    }

    h3 {
        border-bottom: 3px solid var(--mau-nhan);
        margin-top: 40px;
        padding-bottom: 8px;
    }

    .nut-noi {
        position: fixed;
        bottom: 16px;
        right: 16px;
        z-index: 100;
        display: grid;
        gap: 8px;
    }

    .nut-noi a {
        font-size: 16px;
        padding: 6px;
    }

    .anh-chu-xuong {
        max-width: 300px;
        margin: 0 auto 20px;
    }