html {
    scroll-behavior: smooth;
}

body {
    background-color: red !important;
    background-size: cover;
    background-position: center;
    font-family: Georgia, 'Times New Roman', Times, serif;
    color: #333;
    margin: 0;
    padding: 0 20px;
}

#container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

nav {
    background-color: #ffffff;
    padding: 10px 0;
    border-radius: 15px;
}

nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
}

nav ul li {
    margin: 0 15px;
}

nav ul li a {
    color: rgb(0, 0, 0);
    text-decoration: none;
    font-size: 18px;
    transition: color 0.3s ease;
}

nav ul li a:hover {
    color: rgb(39, 39, 38);
}

section {
    padding: 20px;
    margin: 20px 0;
    border-radius: 10px;
    background-color: #ffffff;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    border-left: 5px solid rgb(255, 0, 0);
}

h1 {
    color: rgb(255, 255, 255);
    text-align: center;
}

h2, h3, h4, h5, h6 {
    color: rgb(0, 0, 0);
}

p, ul {
    line-height: 1.6;
    padding-left: 20px;
}

a {
    color: red;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

input[type="number"] {
    width: 100%;
    max-width: 300px;
    padding: 10px;
    margin: 5px 0;
    border: 1px solid #ccc;
    border-radius: 5px;
    box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.1);
    font-size: 16px;
}

button {
    background-color: #333;
    color: white;
    padding: 10px 20px;
    margin: 10px 5px;
    border: none;
    border-radius: 5px;
    font-size: 16px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

button:hover {
    background-color: #555;
}

#buttons {
    display: flex;
    justify-content: center;
}

#result {
    margin-top: 20px;
    font-size: 18px;
    font-weight: bold;
    text-align: center;
}

@media (max-width: 768px) {
    body {
        padding: 0 10px;
    }

    nav ul li {
        margin: 0 10px;
    }

    #container {
        padding: 10px;
    }

    .grade-input {
        flex-direction: column;
    }

    .grade-input input {
        width: 100%;
        margin-bottom: 10px;
    }
}

header {
    text-align: center;
    margin-bottom: 20px;
}

iframe {
    display: block;
    margin: 20px auto;
    width: 100%;
    max-width: 800px;
    height: 315px;

}