/* ============================================================
   蜜聊官网样式
   - 移动优先 + 渐进增强
   - 无任何第三方依赖 (无 Tailwind / 无字体 CDN)
   ============================================================ */

/* ---------- Design Tokens ---------- */
:root {
    --brand-50:  #FFF5FA;
    --brand-100: #FFE4F1;
    --brand-200: #FFC8E2;
    --brand-400: #FF6B9D;
    --brand-600: #C44BFF;
    --brand-700: #9A2DE0;

    --ink-900: #1a1a2e;
    --ink-700: #3d3d52;
    --ink-500: #6b7280;
    --ink-400: #9ca3af;

    --brand-grad: linear-gradient(135deg, #C44BFF 0%, #FF6B9D 100%);
    --shadow-brand: 0 10px 30px -10px rgba(196, 75, 255, 0.55);
    --shadow-card-hover: 0 20px 40px -20px rgba(196, 75, 255, 0.25);

    --container: 72rem;       /* 1152px */
    --radius-sm: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    --radius-pill: 9999px;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
    margin: 0;
    font-family: "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
    color: var(--ink-900);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    min-height: 100vh;
    min-height: 100dvh;
    display: flex;
    flex-direction: column;
    background-color: #fff;
    /* 柔和粉紫光晕背景 */
    background-image:
        radial-gradient(ellipse 70% 50% at 20% 0%, rgba(196, 75, 255, 0.12), transparent 60%),
        radial-gradient(ellipse 80% 50% at 90% 20%, rgba(255, 107, 157, 0.12), transparent 60%),
        radial-gradient(ellipse 60% 40% at 50% 100%, rgba(196, 75, 255, 0.06), transparent 60%);
    background-attachment: fixed;
}

a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; height: auto; }
h1, h2, h3, p { margin: 0; }
ul { margin: 0; padding: 0; list-style: none; }
button { font: inherit; cursor: pointer; }

/* ---------- Layout helpers ---------- */
.container {
    width: 100%;
    max-width: var(--container);
    margin-inline: auto;
    padding-inline: 1rem;
}
@media (min-width: 640px) {
    .container { padding-inline: 1.5rem; }
}

main { flex-grow: 1; }

/* 桌面/移动切换显示 (用于换行控制) */
.mobile-only { display: inline; }
.desktop-only { display: none; }
@media (min-width: 640px) {
    .mobile-only { display: none; }
    .desktop-only { display: inline; }
}

/* 渐变文字 */
.gradient-text {
    background: var(--brand-grad);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: transparent;
}

/* ---------- Header ---------- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(255, 255, 255, 0.75);
    backdrop-filter: saturate(180%) blur(14px);
    -webkit-backdrop-filter: saturate(180%) blur(14px);
    border-bottom: 1px solid rgba(255, 228, 241, 0.7);
}
.nav-inner {
    max-width: var(--container);
    margin-inline: auto;
    padding-inline: 1rem;
    height: 3.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}
@media (min-width: 640px) {
    .nav-inner {
        padding-inline: 1.5rem;
        height: 4rem;
    }
}
.nav-brand {
    display: flex;
    align-items: center;
    gap: 0.625rem;
}
.brand-logo {
    width: 2rem;
    height: 2rem;
    border-radius: var(--radius-md);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
}
@media (min-width: 640px) {
    .brand-logo { width: 2.25rem; height: 2.25rem; }
}
.brand-name {
    font-size: 1.125rem;
    font-weight: 700;
}
@media (min-width: 640px) {
    .brand-name { font-size: 1.25rem; }
}
.nav-links {
    display: none;
    gap: 1.75rem;
    font-size: 0.875rem;
    color: var(--ink-700);
}
@media (min-width: 640px) {
    .nav-links { display: flex; }
}
.nav-links a { transition: color 0.2s ease; }
.nav-links a:hover { color: var(--brand-600); }

/* ---------- Buttons ---------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.625rem;
    padding: 0.875rem 1.75rem;
    border-radius: var(--radius-pill);
    font-weight: 600;
    font-size: 1rem;
    border: 0;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease, background-color 0.2s ease;
    white-space: nowrap;
}
.btn:focus-visible {
    outline: 3px solid rgba(196, 75, 255, 0.4);
    outline-offset: 2px;
}
.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.75rem;
}
@media (min-width: 640px) {
    .btn-sm { padding: 0.625rem 1.25rem; font-size: 0.875rem; }
}
.btn-primary {
    background: var(--brand-grad);
    color: #fff;
    box-shadow: var(--shadow-brand);
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 14px 36px -10px rgba(196, 75, 255, 0.7);
}
.btn-primary:active { transform: translateY(0); }

.btn-secondary {
    background: #fff;
    color: var(--ink-900);
    border: 2px solid var(--brand-100);
}
.btn-secondary:hover {
    border-color: var(--brand-400);
    transform: translateY(-2px);
    box-shadow: 0 10px 24px -12px rgba(255, 107, 157, 0.4);
}
.btn-secondary:active { transform: translateY(0); }

.btn-icon { width: 1.25rem; height: 1.25rem; flex-shrink: 0; }
.btn-secondary .btn-icon { color: var(--brand-600); }

/* ---------- Hero ---------- */
.hero {
    padding: 3rem 1rem;
    text-align: center;
}
@media (min-width: 640px) {
    .hero { padding: 5rem 1.5rem; }
}
.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.375rem 0.75rem;
    background: var(--brand-50);
    border: 1px solid var(--brand-100);
    border-radius: var(--radius-pill);
    font-size: 0.75rem;
    color: var(--brand-600);
    font-weight: 500;
    letter-spacing: 0.025em;
    margin-bottom: 1.5rem;
}
@media (min-width: 640px) {
    .hero-badge { font-size: 0.875rem; margin-bottom: 2rem; }
}
.hero-badge .dot {
    width: 0.375rem;
    height: 0.375rem;
    background: var(--brand-400);
    border-radius: 50%;
    animation: pulse 2s ease-in-out infinite;
}
.hero-logo {
    display: flex;
    justify-content: center;
    margin-bottom: 1.5rem;
}
.hero-logo img {
    width: 5rem;
    height: 5rem;
    border-radius: 1.5rem;
    box-shadow: 0 20px 40px -15px rgba(196, 75, 255, 0.4);
    animation: float 4s ease-in-out infinite;
}
@media (min-width: 640px) {
    .hero-logo { margin-bottom: 2rem; }
    .hero-logo img { width: 6rem; height: 6rem; }
}
.hero-title {
    font-size: 2.25rem;
    font-weight: 700;
    line-height: 1.15;
    letter-spacing: -0.025em;
    margin-bottom: 1.25rem;
}
@media (min-width: 640px) {
    .hero-title { font-size: 3rem; margin-bottom: 1.5rem; }
}
@media (min-width: 768px) {
    .hero-title { font-size: 3.75rem; }
}
.hero-subtitle {
    font-size: 1rem;
    color: var(--ink-500);
    max-width: 36rem;
    margin: 0 auto 2.25rem;
    line-height: 1.7;
    padding-inline: 0.5rem;
}
@media (min-width: 640px) {
    .hero-subtitle { font-size: 1.125rem; margin-bottom: 3rem; }
}
.hero-actions {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    align-items: stretch;
    max-width: 22rem;
    margin: 0 auto;
}
@media (min-width: 640px) {
    .hero-actions {
        flex-direction: row;
        gap: 1rem;
        justify-content: center;
        align-items: center;
        max-width: none;
    }
    .hero-actions .btn { min-width: 12.5rem; }
}
.hero-note {
    margin-top: 1.5rem;
    font-size: 0.75rem;
    color: var(--ink-400);
}
@media (min-width: 640px) {
    .hero-note { margin-top: 2rem; font-size: 0.875rem; }
}

/* ---------- Features ---------- */
.features { padding: 3.5rem 1rem; }
@media (min-width: 640px) {
    .features { padding: 5rem 1.5rem; }
}
.section-head {
    text-align: center;
    margin-bottom: 2.5rem;
}
@media (min-width: 640px) {
    .section-head { margin-bottom: 3.5rem; }
}
.section-head h2 {
    font-size: 1.875rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
}
@media (min-width: 640px) {
    .section-head h2 { font-size: 2.25rem; }
}
.section-head p {
    color: var(--ink-500);
    font-size: 0.875rem;
}
@media (min-width: 640px) {
    .section-head p { font-size: 1rem; }
}

.feature-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
}
@media (min-width: 640px) {
    .feature-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.25rem;
    }
}
@media (min-width: 1024px) {
    .feature-grid { grid-template-columns: repeat(4, 1fr); }
}

.feature-card {
    background: #fff;
    border: 1px solid var(--brand-100);
    border-radius: var(--radius-xl);
    padding: 1.5rem;
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-card-hover);
    border-color: var(--brand-200);
}
.feature-icon {
    width: 3rem;
    height: 3rem;
    border-radius: var(--radius-md);
    background: var(--brand-grad);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
    box-shadow: 0 8px 20px -8px rgba(196, 75, 255, 0.6);
    color: #fff;
}
.feature-icon svg { width: 1.5rem; height: 1.5rem; }
.feature-card h3 {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}
@media (min-width: 640px) {
    .feature-card h3 { font-size: 1.125rem; }
}
.feature-card p {
    font-size: 0.875rem;
    color: var(--ink-500);
    line-height: 1.7;
}

/* ---------- Footer ---------- */
.site-footer {
    padding: 2rem 1rem;
    border-top: 1px solid rgba(255, 228, 241, 0.8);
}
@media (min-width: 640px) {
    .site-footer { padding: 2rem 1.5rem; }
}
.footer-inner {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
    font-size: 0.875rem;
    color: var(--ink-400);
}
@media (min-width: 640px) {
    .footer-inner { flex-direction: row; }
}
.footer-brand {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.footer-brand img {
    width: 1.5rem;
    height: 1.5rem;
    border-radius: var(--radius-sm);
}
.footer-brand span {
    font-weight: 600;
    color: var(--ink-700);
}
.footer-links {
    display: flex;
    gap: 1.25rem;
}
.footer-links a { transition: color 0.2s ease; }
.footer-links a:hover { color: var(--brand-600); }

/* ---------- Animations ---------- */
@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.4; }
}
@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-6px); }
}
/* ---------- Steps (3 步开启) ---------- */
.steps { padding: 3.5rem 1rem; }
@media (min-width: 640px) {
    .steps { padding: 5rem 1.5rem; }
}
.steps-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
}
@media (min-width: 768px) {
    .steps-grid { grid-template-columns: repeat(3, 1fr); gap: 1.5rem; }
}
.step-card {
    background: #fff;
    border: 1px solid var(--brand-100);
    border-radius: var(--radius-xl);
    padding: 2rem 1.5rem;
    transition: transform 0.25s ease, box-shadow 0.25s ease;
}
.step-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-card-hover);
}
.step-num {
    font-size: 3rem;
    font-weight: 800;
    background: var(--brand-grad);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: transparent;
    line-height: 1;
    margin-bottom: 1rem;
    letter-spacing: -0.05em;
}
@media (min-width: 640px) {
    .step-num { font-size: 3.5rem; }
}
.step-card h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}
.step-card p {
    font-size: 0.875rem;
    color: var(--ink-500);
    line-height: 1.7;
}

/* ---------- Scenes (使用场景) ---------- */
.scenes { padding: 3.5rem 1rem; }
@media (min-width: 640px) {
    .scenes { padding: 5rem 1.5rem; }
}
.scenes-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
}
@media (min-width: 640px) {
    .scenes-grid { grid-template-columns: repeat(2, 1fr); gap: 1.25rem; }
}
@media (min-width: 1024px) {
    .scenes-grid { grid-template-columns: repeat(4, 1fr); }
}
.scene-card {
    background: linear-gradient(180deg, #FFF5FA 0%, #ffffff 100%);
    border: 1px solid var(--brand-100);
    border-radius: var(--radius-xl);
    padding: 1.75rem 1.25rem;
    text-align: center;
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.scene-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-card-hover);
    border-color: var(--brand-200);
}
.scene-icon {
    width: 3.5rem;
    height: 3.5rem;
    border-radius: var(--radius-pill);
    background: #fff;
    border: 1px solid var(--brand-100);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
    color: var(--brand-600);
}
.scene-icon svg { width: 1.5rem; height: 1.5rem; }
.scene-card h3 {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}
.scene-card p {
    font-size: 0.875rem;
    color: var(--ink-500);
    line-height: 1.6;
}

/* ---------- CTA Band (粉紫渐变横幅) ---------- */
.cta-band { padding: 3.5rem 1rem; }
@media (min-width: 640px) {
    .cta-band { padding: 5rem 1.5rem; }
}
.cta-inner {
    max-width: 56rem;
    margin: 0 auto;
    background: var(--brand-grad);
    border-radius: 2rem;
    padding: 2.5rem 1.5rem;
    text-align: center;
    color: #fff;
    box-shadow: 0 30px 60px -20px rgba(196, 75, 255, 0.5);
}
@media (min-width: 640px) {
    .cta-inner { padding: 4rem 3rem; }
}
.cta-inner h2 {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: #fff;
}
@media (min-width: 640px) {
    .cta-inner h2 { font-size: 2.25rem; }
}
.cta-inner > p {
    color: rgba(255, 255, 255, 0.9);
    font-size: 1rem;
    margin-bottom: 2rem;
}
.cta-actions {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    align-items: stretch;
    max-width: 22rem;
    margin: 0 auto;
}
@media (min-width: 640px) {
    .cta-actions {
        flex-direction: row;
        gap: 1rem;
        justify-content: center;
        align-items: center;
        max-width: none;
    }
    .cta-actions .btn { min-width: 12.5rem; }
}
.btn-on-brand {
    background: #fff;
    color: var(--brand-600);
}
.btn-on-brand:hover {
    transform: translateY(-2px);
    box-shadow: 0 14px 30px -10px rgba(0, 0, 0, 0.25);
}
.btn-on-brand-outline {
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
    color: #fff;
    border: 2px solid rgba(255, 255, 255, 0.45);
}
.btn-on-brand-outline:hover {
    background: rgba(255, 255, 255, 0.25);
    transform: translateY(-2px);
}

/* ---------- FAQ ---------- */
.faq { padding: 3.5rem 1rem; }
@media (min-width: 640px) {
    .faq { padding: 5rem 1.5rem; }
}
.faq-list {
    max-width: 48rem;
    margin: 0 auto;
}
.faq-item {
    background: #fff;
    border: 1px solid var(--brand-100);
    border-radius: var(--radius-lg);
    padding: 1.25rem 1.5rem;
    margin-bottom: 0.75rem;
    transition: border-color 0.25s ease, box-shadow 0.25s ease;
}
.faq-item:hover {
    border-color: var(--brand-200);
    box-shadow: 0 10px 24px -16px rgba(196, 75, 255, 0.3);
}
.faq-item dt {
    font-weight: 700;
    font-size: 1rem;
    margin-bottom: 0.5rem;
    color: var(--ink-900);
    position: relative;
    padding-left: 1.75rem;
}
.faq-item dt::before {
    content: 'Q';
    position: absolute;
    left: 0;
    top: -0.0625rem;
    color: var(--brand-600);
    font-weight: 800;
    font-size: 1.125rem;
}
.faq-item dd {
    margin: 0;
    color: var(--ink-500);
    font-size: 0.9375rem;
    line-height: 1.75;
    padding-left: 1.75rem;
}

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}