:root {
    --primary: #007AFF;
    --dark: #1D1D1F;
    --light: #F5F5F7;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    color: var(--dark);
    line-height: 1.6;
    margin: 0;
    background-color: white;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Language Switching Logic */
body.lang-zh .en {
    display: none;
}

body.lang-en .zh {
    display: none;
}

.header-content {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.lang-switcher {
    margin: 15px 0;
    display: flex;
    gap: 10px;
}

.lang-switcher button {
    background: transparent;
    border: 1px solid rgba(255, 255, 255, 0.4);
    color: white;
    padding: 6px 14px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.85em;
    transition: all 0.2s;
}

.lang-switcher button.active {
    background: white;
    color: var(--dark);
    border-color: white;
}

.lang-switcher button:hover:not(.active) {
    border-color: white;
    background: rgba(255, 255, 255, 0.1);
}

header {
    background: var(--dark);
    color: white;
    padding: 40px 0;
    text-align: center;
}

.header-nav {
    margin-top: 20px;
}

.header-nav a {
    color: white;
    text-decoration: none;
    margin: 0 15px;
    font-weight: 500;
    opacity: 0.8;
}

.header-nav a:hover {
    opacity: 1;
    text-decoration: underline;
}

header h1 {
    margin: 0;
    font-size: 2.5em;
    font-weight: 700;
}

main {
    padding: 40px 0;
}

.hero {
    text-align: center;
    margin-bottom: 60px;
}

.hero h2 {
    font-size: 2em;
}

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 60px;
}

.feature-item {
    background: var(--light);
    padding: 20px;
    border-radius: 12px;
    text-align: center;
}

.section {
    margin-bottom: 40px;
    padding: 40px;
    background: var(--light);
    border-radius: 18px;
}

footer {
    text-align: center;
    padding: 40px 0;
    color: #888;
    font-size: 0.9em;
}

footer a {
    color: #888;
    text-decoration: underline;
}

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

ul {
    padding-left: 20px;
}

a {
    color: var(--primary);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}