/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: '思源黑体 CN Regular', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f8f9fa; /* Light grey background */
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
}

h1, h2, h3, h4 {
    font-family: '思源黑体 CN Bold', 'Microsoft YaHei Bold', sans-serif;
    margin-bottom: 1rem;
}

h2 {
    text-align: center;
    color: #003366; /* Dark Blue for headings */
    margin-bottom: 2.5rem;
    font-size: 2.2rem;
    position: relative;
    padding-bottom: 10px;
}
h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 3px;
    background-color: #2E8B57; /* Healthy Green underline */
}

a {
    text-decoration: none;
    color: #2E8B57; /* Healthy Green for links */
}

a:hover {
    color: #1e5a3a;
}

section {
    padding: 60px 0;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 10px 25px;
    border-radius: 25px;
    background-color: #D4AF37; /* Gold emphasis */
    color: #fff;
    font-weight: bold;
    transition: background-color 0.3s ease;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn:hover {
    background-color: #b89a30; /* Darker Gold */
    color: #fff;
}

.btn-secondary {
     background-color: #4682B4; /* Tech Blue */
}
 .btn-secondary:hover {
     background-color: #366690; /* Darker Tech Blue */
 }

/* Header & Navigation */
.main-header {
    background-color: #fff;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 10px 0;
}

.main-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.8rem;
    font-weight: bold;
    color: #2E8B57; /* Healthy Green */
}
 .logo span {
    color: #4682B4; /* Tech Blue */
    font-size: 0.8em;
 }


.main-nav ul {
    list-style: none;
    display: flex;
}

.main-nav ul li {
    margin-left: 25px;
}

.main-nav ul li a {
    color: #333;
    font-weight: 500;
    padding: 5px 0;
    position: relative;
    transition: color 0.3s ease;
}

.main-nav ul li a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: #2E8B57; /* Healthy Green */
    transition: width 0.3s ease;
}

.main-nav ul li a:hover,
.main-nav ul li a.active {
    color: #2E8B57; /* Healthy Green */
}

.main-nav ul li a:hover::after,
.main-nav ul li a.active::after {
     width: 100%;
}

.header-actions {
    display: flex;
    align-items: center;
}

.header-actions .language-switcher {
    margin-right: 15px;
    font-size: 0.9rem;
    background-color: #f8f9fa; /* 背景色 */
    border-radius: 5px; /* 圆角 */
    padding: 5px; /* 内边距 */
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1); /* 阴影效果 */
}

.menu-toggle {
    display: none; /* Hidden by default on larger screens */
    font-size: 1.5rem;
    cursor: pointer;
    border: none;
    background: none;
    color: #333; /* Ensure it's visible */
    padding: 5px;
}


/* Footer */
.main-footer {
    background-color: #002b51; /* Darker Blue for footer */
    color: #ccc;
    padding: 50px 0 20px;
    font-size: 0.9rem;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
    margin-bottom: 40px;
}

.footer-column h5 {
    color: #fff;
    margin-bottom: 15px;
    font-size: 1.1rem;
}

.footer-column ul {
    list-style: none;
    padding: 0; /* Ensure no default padding */
}

.footer-column ul li {
    margin-bottom: 10px;
}

.footer-column ul li a {
    color: #ccc;
    transition: color 0.3s ease;
}

.footer-column ul li a:hover {
    color: #D4AF37; /* Gold */
}

.footer-column p {
     line-height: 1.8;
}

.social-links a {
    color: #ccc;
    margin-right: 15px;
    font-size: 1.3rem;
    transition: color 0.3s ease;
}
.social-links a:hover {
     color: #D4AF37; /* Gold */
}


.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid #004075; /* Slightly lighter border */
    font-size: 0.85rem;
    color: #aaa;
}

/* Utility Classes */
.text-center { text-align: center; }
.mt-4 { margin-top: 40px; }

/* Simple fade-in animation */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}
.fade-in {
   animation: fadeIn 0.6s ease-out forwards;
   opacity: 0; /* Start hidden for JS IntersectionObserver */
}


/* Base Responsive Design (Header/Footer/General) */
@media (max-width: 992px) {
    .main-nav ul {
        display: none; /* Hide on smaller screens initially */
        flex-direction: column;
        position: absolute;
        top: 100%; /* Position below header */
        left: 0;
        width: 100%;
        background-color: #fff;
        box-shadow: 0 4px 10px rgba(0,0,0,0.1);
        border-top: 1px solid #eee;
    }
    .main-nav ul.active {
         display: flex; /* Show when active */
    }

    .main-nav ul li {
        margin: 0; /* Remove left margin */
    }
    .main-nav ul li a {
        display: block; /* Make links full width */
        padding: 12px 20px; /* Add padding */
        text-align: center;
        border-bottom: 1px solid #eee;
    }
    .main-nav ul li:last-child a {
        border-bottom: none;
    }

    .main-nav ul li a::after {
        display: none; /* Hide underlines on mobile */
    }
     .menu-toggle {
        display: block; /* Show toggle button */
     }
}

@media (max-width: 768px) {
    h2 { font-size: 1.8rem; }
    .footer-grid {
       grid-template-columns: 1fr; /* Stack columns */
    }
    .main-header .container {
       padding: 0 20px;
    }
    .logo { font-size: 1.5rem; }
    .btn { padding: 8px 20px; font-size: 0.9rem;}
}

/* Hide menu toggle on PC */
@media (min-width: 993px) {
    .menu-toggle {
        display: none;
    }
}