body {
    font-family: 'Segoe UI', 'Arial', sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background-color: #fafafa;
    color: #333;
    font-size: 18px;
}

header {
    background-color: #333;
    color: #fff;
    padding: 20px;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}

nav a {
    color: #fff;
    margin: 0 15px;
    text-decoration: none;
    font-weight: 500;
    padding: 6px 12px;
    border-radius: 4px;
    transition: background 0.2s;
}
nav a.active, nav a:hover {
    background: #555;
}

main {
    padding: 20px;
    max-width: 800px;
    margin: 0 auto;
    background: #fff;
    border-radius: 8px;
    box-shadow: 0 2px 16px rgba(0,0,0,0.04);
}

footer {
    text-align: center;
    padding: 10px;
    background-color: #eee;
    position: relative;
    bottom: 0;
    width: 100%;
    font-size: 16px;
}

.post-list {
    list-style: none;
    padding: 0;
}

.post-list li {
    margin-bottom: 10px;
    font-size: 20px;
}

.profile-photo {
    width: 150px;
    border-radius: 50%;
    box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}

/* 回到頂部按鈕 */
#backToTop {
    display: none;
    position: fixed;
    bottom: 40px;
    right: 40px;
    background: #333;
    color: #fff;
    border: none;
    border-radius: 50%;
    width: 48px;
    height: 48px;
    font-size: 24px;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(0,0,0,0.12);
    z-index: 100;
    transition: background 0.2s;
}
#backToTop:hover {
    background: #555;
}

/* 響應式設計 */
@media (max-width: 600px) {
    main {
        padding: 10px;
        max-width: 100%;
        border-radius: 0;
        box-shadow: none;
    }
    header {
        padding: 10px;
    }
    .profile-photo {
        width: 100px;
    }
    .post-list li {
        font-size: 16px;
    }
}