:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --bg-light: #f3f4f6;
    --white: #ffffff;
    --gradient-start: #4f46e5;
    --gradient-end: #06b6d4;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    width: 100%;
}

.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
}

.btn-primary {
    background-color: var(--primary-color);
    color: var(--white);
    box-shadow: 0 4px 6px rgba(37, 99, 235, 0.2);
}

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
}

.btn-outline {
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    background: transparent;
}

.btn-outline:hover {
    background-color: var(--primary-color);
    color: var(--white);
}

.navbar {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 15px 0;
}

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

.nav-brand {
    font-weight: 800;
    font-size: 1.25rem;
    text-decoration: none;
    background: linear-gradient(to right, var(--gradient-start), var(--gradient-end));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: flex;
    align-items: center;
    gap: 10px;
}

.nav-brand:hover {
    opacity: 0.8;
}

/* Dropdown Language Switcher */
.lang-dropdown {
    position: relative;
    display: inline-block;
}

.lang-btn {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    background: #f3f4f6;
    border-radius: 8px;
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 600;
    font-size: 14px;
    border: none;
    cursor: pointer;
    transition: background 0.2s;
}

.lang-btn:hover {
    background: #e5e7eb;
}

.dropdown-menu {
    display: none;
    position: absolute;
    right: 0;
    top: 100%;
    background-color: var(--white);
    min-width: 140px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    z-index: 1001;
    border-radius: 12px;
    margin-top: 8px;
    padding: 6px;
    border: 1px solid rgba(0,0,0,0.05);
    transform-origin: top right;
    animation: dropdownFade 0.2s ease-out;
}

.lang-dropdown.show .dropdown-menu {
    display: block;
}

.dropdown-item {
    color: var(--text-dark);
    padding: 10px 12px;
    text-decoration: none;
    display: block;
    font-size: 14px;
    border-radius: 6px;
    transition: all 0.2s;
}

.dropdown-item:hover {
    background-color: #f3f4f6;
    color: var(--primary-color);
}

.dropdown-item.active {
    background-color: #eff6ff;
    color: var(--primary-color);
    font-weight: 600;
}

@keyframes dropdownFade {
    from {
        opacity: 0;
        transform: scale(0.95);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.lang-icon {
    font-size: 16px;
}

.chevron-down {
    font-size: 10px;
    opacity: 0.5;
}

body.lang-en [lang="zh"] {
    display: none;
}

body.lang-zh [lang="en"] {
    display: none;
}

footer {
    padding: 40px 0;
    text-align: center;
    color: var(--text-light);
    border-top: 1px solid #e5e7eb;
    background: var(--white);
    margin-top: auto;
}

.footer-links {
    margin-bottom: 20px;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 24px;
}

.footer-links a {
    color: var(--text-light);
    text-decoration: none;
    font-size: 0.95rem;
    transition: color 0.2s;
}

.footer-links a:hover {
    color: var(--primary-color);
}