:root {
    --primary-color: #2A7AE5;
    --primary-dark: #1e5bb0;
    --text-color: #333333;
    --text-light: #666666;
    --bg-color: #ffffff;
    --bg-light: #f5f7fa;
    --border-color: #e1e4e8;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px rgba(0,0,0,0.1);
    --radius: 8px;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header & Nav */
header {
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
}

.logo img {
    height: 40px;
    width: auto;
}

.nav-links {
    display: flex;
    gap: 20px;
    align-items: center;
}

.lang-switch {
    padding: 6px 12px;
    border: 1px solid var(--primary-color);
    color: var(--primary-color);
    border-radius: 20px;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.9rem;
    transition: all 0.3s ease;
    background: transparent;
}

.lang-switch:hover {
    background-color: var(--primary-color);
    color: white;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #f5f7fa 0%, #eef2f7 100%);
    padding: 80px 0;
    text-align: center;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 20px;
    color: var(--text-color);
    line-height: 1.2;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-light);
    max-width: 800px;
    margin: 0 auto;
}

/* Section Styles */
section {
    padding: 60px 0;
}

section:nth-child(even) {
    background-color: var(--bg-light);
}

.section-title {
    text-align: center;
    margin-bottom: 50px;
}

.section-title h2 {
    font-size: 2rem;
    color: var(--text-color);
    margin-bottom: 15px;
    position: relative;
    display: inline-block;
}

.section-title h2::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background-color: var(--primary-color);
    margin: 10px auto 0;
    border-radius: 2px;
}

/* About Grid */
.about-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.card {
    background: white;
    padding: 30px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.card h3 {
    color: var(--primary-color);
    margin-bottom: 15px;
    font-size: 1.25rem;
}

/* Necessity List */
.necessity-list {
    list-style: none;
}

.necessity-list li {
    margin-bottom: 20px;
    padding-left: 20px;
    position: relative;
}

.necessity-list li::before {
    content: '•';
    color: var(--primary-color);
    font-size: 1.5em;
    position: absolute;
    left: 0;
    top: -5px;
}

/* Members Section */
.members-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.member-card {
    text-align: center;
    background: white;
    padding: 30px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
}

.member-role {
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 10px;
    display: block;
    text-transform: uppercase;
    font-size: 0.85rem;
    letter-spacing: 1px;
}

.member-name {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 5px;
}

.member-org {
    color: var(--text-light);
    font-size: 0.9rem;
}

/* Gallery */
.gallery {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-top: 40px;
}

.gallery img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: var(--radius);
    transition: transform 0.3s ease;
}

.gallery img:hover {
    transform: scale(1.05);
}

/* Footer */
footer {
    background-color: #1a1a1a;
    color: white;
    padding: 60px 0 20px;
    text-align: center;
}

.footer-content {
    margin-bottom: 40px;
}

.copyright {
    color: #888;
    font-size: 0.9rem;
    border-top: 1px solid #333;
    padding-top: 20px;
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 1.8rem;
    }
    
    .nav-links {
        display: flex; /* Keep language switch visible on mobile */
    }
    
    section {
        padding: 40px 0;
    }
}

/* Utility */
.hidden {
    display: none !important;
}

/* Language Toggling */
body.lang-en .lang-cn {
    display: none !important;
}

body.lang-cn .lang-en {
    display: none !important;
}