body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background-color: #f9f9f9;
}

main {
    width: 90%;
    max-width: 800px;
    margin: 20px auto;
    padding: 20px;
    background: white;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    border-radius: 8px;
}

h1, h2, h3 {
    color: #333;
}

p {
    color: #666;
}

section {
    margin-bottom: 20px;
}

h2 {
    border-bottom: 2px solid #ddd;
    padding-bottom: 5px;
}

h3 {
    margin-top: 15px;
}

/* ????????? */
header {
    background: #007bff;
    color: white;
    padding: 10px 0;
    text-align: center;
}

nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

nav ul li {
    display: inline;
    margin: 0 15px;
}

nav ul li a {
    color: white;
    text-decoration: none;
    font-weight: bold;
}

nav ul li a:hover {
    text-decoration: underline;
}

/* ????????? */
footer {
    background: #007bff;
    color: white;
    text-align: center;
    padding: 10px 0;
    margin-top: 20px;
}

footer p {
    color: white;
}

.tutorial-step {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 30px;
}

.tutorial-step .text {
    width: 50%;
    padding: 10px;
}

.tutorial-step .image-placeholder {
    width: 50%;
    display: flex;
    justify-content: center;
}

.tutorial-step img {
    width: 80%;
    height: auto;
    max-width: 1242px;
    max-height: 2688px;    
    background-color: #f0f0f0;
}

hr {
    border: none;
    border-top: 2px solid #ddd;
    margin: 30px 0;
}


/* ????? */
@media (max-width: 768px) {
    .tutorial-step {
        flex-direction: column;
        text-align: center;
    }
    
    .tutorial-step .text, 
    .tutorial-step .image-placeholder {
        width: 100%;
    }

    .tutorial-step img {
        width: 100%;
    }
}