body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

.main-header {
    background-color: #ffffff;
    color: #333;
    padding: 10px 40px;
    width: 100%;
    box-sizing: border-box;
    position: sticky;
    top: 0;
    z-index: 1000;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid #e7e7e7;
    box-shadow: 0 2px 4px rgba(0,0,0,0.04);
}
.main-header h1 {
    margin: 0;
    font-size: 1.8em;
    color: #333333;
}
.main-nav {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
}
.main-nav a {
    color: #555555;
    padding: 8px 15px;
    text-decoration: none;
    margin: 0 5px;
    border-radius: 4px;
    background-color: transparent;
    transition: color 0.3s, background-color 0.3s;
    font-weight: 600;
}
.main-nav a:hover {
    color: #000000;
    background-color: #f5f5f5;
}
.main-nav a.active {
    color: #fff;
    background-color: #007bff;
}
.main-footer {
    background-color: #f8f9fa;
    color: #6c757d;
    text-align: center;
    padding: 20px;
    font-size: 0.9em;
    width: 100%;
    box-sizing: border-box;
    border-top: 1px solid #e7e7e7;
}

.hamburger {
    display: none;
    cursor: pointer;
    background: transparent;
    border: none;
    padding: 0;
    z-index: 1001;
}

.hamburger .bar {
    display: block;
    width: 25px;
    height: 3px;
    margin: 5px auto;
    transition: all 0.3s ease-in-out;
    background-color: #333;
}

@media (max-width: 768px) {
    .main-header {
        padding: 15px 20px;
    }

    .main-header h1 {
        margin-bottom: 0;
        font-size: 1.5em;
    }

    .main-nav {
        position: fixed;
        left: -100%;
        top: 55px; /* Adjusted to match header height */
        flex-direction: column;
        background-color: #ffffff;
        width: 100%;
        height: calc(100vh - 55px);
        transition: left 0.3s ease-in-out;
        padding-top: 20px;
        gap: 0.5rem;
        box-shadow: 2px 0 5px rgba(0,0,0,0.1);
    }
    .main-nav.active {
        left: 0;
    }
    .main-nav a {
        font-size: 1.1em;
        padding: 15px;
        width: 100%;
        text-align: center;
        margin: 0;
    }
    .hamburger {
        display: block;
    }
    .hamburger.active .bar:nth-child(2) {
        opacity: 0;
    }
    .hamburger.active .bar:nth-child(1) {
        transform: translateY(8px) rotate(45deg);
    }
    .hamburger.active .bar:nth-child(3) {
        transform: translateY(-8px) rotate(-45deg);
    }
}

#backToTopBtn {
    display: none; /* Hidden by default */
    position: fixed;
    bottom: 20px;
    right: 30px;
    z-index: 99;
    font-size: 18px;
    border: none;
    outline: none;
    background-color: #007bff;
    color: white;
    cursor: pointer;
    padding: 15px;
    border-radius: 10px;
    transition: background-color 0.3s;
}

#backToTopBtn:hover {
    background-color: #0056b3; /* A darker blue on hover */
}