/* ── Reset & Base ── */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --bg: #0a0a0f;
    --bg-card: rgba(18, 18, 30, 0.6);
    --border: rgba(255, 255, 255, 0.08);
    --text: #e4e4ec;
    --text-muted: #8888a0;
    --accent-blue: #4A9EFF;
    --accent-purple: #A855F7;
    --accent-cyan: #22D3EE;
    --radius: 20px;
    --radius-sm: 12px;
    --max-width: 800px;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

/* ── Animated Background Gradient ── */
.bg-gradient {
    position: fixed;
    inset: 0;
    z-index: -1;
    background:
        radial-gradient(ellipse 80% 60% at 20% 10%, rgba(74, 158, 255, 0.12), transparent),
        radial-gradient(ellipse 60% 50% at 80% 30%, rgba(168, 85, 247, 0.10), transparent),
        radial-gradient(ellipse 70% 40% at 50% 80%, rgba(34, 211, 238, 0.08), transparent);
    animation: gradientShift 14s ease-in-out infinite alternate;
}

@keyframes gradientShift {
    0%   { opacity: 0.7; transform: scale(1); }
    50%  { opacity: 1; transform: scale(1.05); }
    100% { opacity: 0.7; transform: scale(1); }
}

/* ── Glass Card ── */
.glass-card {
    background: var(--bg-card);
    backdrop-filter: blur(24px) saturate(180%);
    -webkit-backdrop-filter: blur(24px) saturate(180%);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 2rem;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.glass-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 32px rgba(74, 158, 255, 0.08);
}

/* ── Links ── */
a {
    color: var(--accent-blue);
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    color: var(--accent-cyan);
}

.text-link {
    display: inline-block;
    margin-top: 1rem;
    font-weight: 500;
}

/* ── Language Switcher ── */
.lang-switcher {
    position: fixed;
    top: 1rem;
    right: 1.25rem;
    z-index: 1000;
    display: flex;
    background: var(--bg-card);
    backdrop-filter: blur(24px) saturate(180%);
    -webkit-backdrop-filter: blur(24px) saturate(180%);
    border: 1px solid var(--border);
    border-radius: 100px;
    padding: 3px;
    gap: 2px;
}

.lang-switcher button {
    padding: 6px 14px;
    border: none;
    border-radius: 100px;
    background: transparent;
    color: var(--text-muted);
    font-size: 0.8rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.25s ease;
    font-family: inherit;
}

.lang-switcher button.active {
    background: var(--accent-blue);
    color: #fff;
}

.lang-switcher button:hover:not(.active) {
    color: var(--text);
}

/* Bilingual text visibility */
html.lang-zh .lang-en { display: none; }
html.lang-en .lang-zh { display: none; }

/* ── Hero ── */
.hero {
    display: flex;
    justify-content: center;
    padding: 3rem 1.5rem 2rem;
}

.hero-card {
    text-align: center;
    max-width: 520px;
    width: 100%;
    padding: 3rem 2rem;
}

.app-icon {
    width: 96px;
    height: 96px;
    border-radius: 22px;
    margin-bottom: 1.5rem;
    box-shadow: 0 4px 20px rgba(74, 158, 255, 0.25);
}

.hero-card h1 {
    font-size: 2.4rem;
    font-weight: 700;
    letter-spacing: -0.5px;
    margin-bottom: 0.3rem;
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.tagline {
    font-size: 1.1rem;
    color: var(--accent-cyan);
    font-weight: 500;
    margin-bottom: 0.8rem;
}

.hero-subtitle {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 1.8rem;
    line-height: 1.7;
}

.app-store-link {
    display: inline-block;
    background: var(--accent-blue);
    color: #fff;
    padding: 0.75rem 2rem;
    border-radius: 100px;
    font-weight: 600;
    font-size: 0.95rem;
    letter-spacing: 0.3px;
    transition: background 0.3s, transform 0.2s;
}

.app-store-link:hover {
    background: var(--accent-purple);
    color: #fff;
    transform: scale(1.03);
}

/* ── Main Content ── */
main {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.5rem 3rem;
}

main section {
    margin-bottom: 2rem;
}

/* ── Features Grid ── */
.features h2 {
    text-align: center;
    font-size: 1.6rem;
    margin-bottom: 1.5rem;
    color: var(--text);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 1.25rem;
}

.feature-card {
    padding: 1.5rem;
    text-align: center;
}

.feature-icon {
    font-size: 2rem;
    display: block;
    margin-bottom: 0.75rem;
}

.feature-card h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text);
}

.feature-card p {
    font-size: 0.875rem;
    color: var(--text-muted);
    line-height: 1.55;
}

/* ── Privacy Summary ── */
.privacy-summary ul {
    list-style: none;
    padding: 0;
    margin: 1rem 0;
}

.privacy-summary li {
    padding: 0.35rem 0;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-muted);
    font-size: 0.925rem;
}

.privacy-summary li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--accent-cyan);
    font-weight: 700;
}

.privacy-summary h2 {
    margin-bottom: 0.6rem;
}

/* ── Support ── */
.support h2 {
    margin-bottom: 0.6rem;
}

.support p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

.support-note {
    margin-top: 1rem;
    font-size: 0.85rem !important;
    font-style: italic;
}

/* ── Footer ── */
footer {
    border-top: 1px solid rgba(255, 255, 255, 0.06);
    padding: 1.5rem;
    text-align: center;
}

.footer-content {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 1.25rem;
    align-items: center;
}

.footer-content p {
    color: var(--text-muted);
    font-size: 0.8rem;
}

.footer-links {
    display: flex;
    gap: 1.25rem;
}

.footer-links a {
    font-size: 0.8rem;
    color: var(--text-muted);
}

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

/* ── Privacy Policy Page ── */
.policy-page {
    max-width: 720px;
    margin: 0 auto;
    padding: 2rem 1.5rem 3rem;
}

.back-link {
    display: inline-block;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.back-link:hover {
    color: var(--accent-blue);
}

.policy-card {
    padding: 2.5rem;
}

.policy-card h1 {
    font-size: 1.8rem;
    margin-bottom: 0.4rem;
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.effective-date {
    color: var(--text-muted);
    font-size: 0.85rem;
    margin-bottom: 2rem;
}

.policy-card section {
    margin-bottom: 1.8rem;
}

.policy-card h2 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text);
}

.policy-card p,
.policy-card li {
    color: var(--text-muted);
    font-size: 0.925rem;
    line-height: 1.65;
}

.policy-card ul {
    padding-left: 1.5rem;
    margin: 0.5rem 0;
}

.policy-card li {
    margin-bottom: 0.35rem;
}

.policy-card strong {
    color: var(--text);
}

.policy-card a {
    color: var(--accent-blue);
}

/* ── Responsive ── */
@media (max-width: 600px) {
    .hero {
        padding: 2rem 1rem 1.5rem;
    }
    .hero-card {
        padding: 2rem 1.25rem;
    }
    .hero-card h1 {
        font-size: 1.8rem;
    }
    .app-icon {
        width: 72px;
        height: 72px;
        border-radius: 18px;
    }
    .features-grid {
        grid-template-columns: 1fr;
    }
    .glass-card {
        padding: 1.25rem;
    }
    .policy-card {
        padding: 1.5rem;
    }
    .footer-content {
        flex-direction: column;
        gap: 0.5rem;
    }
}