*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
    color: #fff;
    background: linear-gradient(45deg, #3a599b, #82a0d8, #4343a3, #3a599b);
    background-size: 400% 400%;
    animation: gradientAnimation 20s ease infinite;
}

@keyframes gradientAnimation {
    0% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
    100% {
        background-position: 0% 50%;
    }
}

header {
    background: linear-gradient(45deg, #3a599b, #82a0d8, #4343a3, #3a599b);
    background-size: 400% 400%;
    animation: gradientAnimation 20s ease infinite;
    color: #fff;
    padding: 2rem;
    text-align: center;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}

h1 {
    margin: 0;
    font-size: 2.5rem;
}

nav ul {
    padding: 0;
    list-style: none;
    display: flex;
    justify-content: center;
    margin-top: 1rem;
}

nav li {
    margin: 0 15px;
}

nav a {
    color: #fff;
    text-decoration: none;
    font-size: 1.1rem;
    padding-bottom: 5px;
    border-bottom: 2px solid transparent;
    transition: border-bottom 0.3s;
}

nav a:hover {
    border-bottom: 2px solid #6a89cc;
}

main {
    padding: 2rem;
}

section {
    background-color: rgba(255, 255, 255, 0.8);
    color: #333;
    border-radius: 8px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

h2 {
    border-bottom: 2px solid #4a69bd;
    padding-bottom: 0.5rem;
    margin-top: 0;
}

table {
    width: 100%;
    margin-top: 1.5rem;
    border-collapse: collapse;
}

th, td {
    padding: 12px 15px;
    border-bottom: 1px solid #eee;
    text-align: left;
}

th {
    background-color: rgba(248, 248, 248, 0.3);
    font-weight: bold;
    white-space: nowrap;
}

tr:last-child th,
tr:last-child td {
    border-bottom: none;
}

footer {
    background: linear-gradient(45deg, #3a599b, #82a0d8, #4343a3, #3a599b);
    background-size: 400% 400%;
    animation: gradientAnimation 20s ease infinite;
    color: #fff;
    padding: 1.5rem;
    text-align: center;
    position: relative;
    bottom: 0;
    width: 100%;
    box-shadow: 0 -2px 5px rgba(0,0,0,0.2);
}

@media (max-width: 768px) {
    header, main, section {
        padding: 1.5rem;
    }

    #logo {
        font-size: 2rem;
    }

    nav ul {
        flex-direction: column;
    }

    nav li {
        margin: 10px 0;
    }

    th, td {
        padding: 8px;
    }
}

#page-top-btn {
    position: fixed;
    right: 20px;
    bottom: 20px;
    width: 50px;
    height: 50px;
    background-color: #4a69bd;
    color: #fff;
    text-align: center;
    line-height: 50px;
    border-radius: 50%;
    text-decoration: none;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s, visibility 0.3s;
}

#page-top-btn.visible {
    opacity: 1;
    visibility: visible;
}

#page-top-btn:hover {
    background-color: #6a89cc;
}

#logo img {
    height: 100px;
    width: auto;
    display: block;
    margin: 0 auto;
    border-radius: 50%;
}