/* =========================================
   Modern Fluid UI - "Dark Obsidian & Aurora"
   ========================================= */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap');

:root {
    /* 深色黑曜石主题 (默认) */
    --bg-base: #09090b; /* Deep charcoal canvas */
    --bg-nav: rgba(9, 9, 11, 0.4);
    --bg-nav-scroll: rgba(9, 9, 11, 0.85);
    --bg-card: rgba(24, 24, 27, 0.4);
    --bg-popular-card: rgba(30, 30, 35, 0.6);
    --text-main: #fafafa;
    --text-muted: #a1a1aa;
    
    /* 核心色彩 - 电紫与青色 */
    --accent-violet: #7928ca;
    --accent-cyan: #00dfd8;
    --btn-gradient: linear-gradient(135deg, var(--accent-violet), var(--accent-cyan));
    --btn-gradient-hover: linear-gradient(135deg, #8a2be2, #00ffff);
    
    /* 玻璃拟物 & 边框 */
    --glass-blur: blur(20px);
    --border-glass: rgba(255, 255, 255, 0.08);
    --border-glow: rgba(0, 223, 216, 0.3);
    
    /* 阴影 */
    --shadow-sm: 0 4px 12px rgba(0,0,0,0.3);
    --shadow-md: 0 8px 32px rgba(0,0,0,0.4);
    --shadow-lg: 0 16px 48px rgba(0,0,0,0.5);
    
    --transition-speed: 0.4s;
}

[data-theme="light"] {
    /* 浅色主题回退，虽然主打深色，但保证切换后依然可用且有质感 */
    --bg-base: #ffffff;
    --bg-nav: rgba(255, 255, 255, 0.5);
    --bg-nav-scroll: rgba(255, 255, 255, 0.9);
    --bg-card: rgba(244, 244, 245, 0.6);
    --bg-popular-card: rgba(121, 40, 202, 0.08); /* light violet tint for light mode */
    --text-main: #09090b;
    --text-muted: #52525b;
    --border-glass: rgba(0, 0, 0, 0.08);
    --shadow-sm: 0 4px 12px rgba(0,0,0,0.05);
    --shadow-md: 0 8px 32px rgba(0,0,0,0.08);
    --shadow-lg: 0 16px 48px rgba(0,0,0,0.12);
}

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

html {
    /* 平滑滚动及锚点偏移在 JS 中实现，但保留基础属性 */
    scroll-behavior: smooth; 
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: var(--bg-base);
    color: var(--text-main);
    line-height: 1.6;
    overflow-x: hidden;
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease;
}

a {
    text-decoration: none;
    color: var(--text-main);
    transition: color 0.3s ease;
}

ul {
    list-style: none;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    position: relative;
    z-index: 2;
}

.section-title {
    text-align: center;
    font-size: 2.25rem;
    margin-bottom: 4rem;
    color: var(--text-main);
    font-weight: 800;
    letter-spacing: -0.02em;
}

.gradient-text {
    background: var(--btn-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: inline-block;
}

section {
    padding: 6rem 0;
    position: relative;
}

/* =========================================
   玻璃卡片 (Glassmorphism Cards) & 涟漪效果
   ========================================= */
.glass-card {
    background: var(--bg-card);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    border: 1px solid var(--border-glass);
    border-radius: 16px;
    padding: 2.5rem;
    transition: transform var(--transition-speed) cubic-bezier(0.2, 0.8, 0.2, 1), box-shadow var(--transition-speed) ease, border-color var(--transition-speed) ease;
    box-shadow: var(--shadow-sm);
    position: relative;
}

.glass-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-md);
    border-color: var(--border-glow);
}

/* 涟漪光晕效果 (Ripple Feedback on hover) */
.ripple-effect {
    overflow: hidden;
}
.ripple-effect::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 150%;
    height: 150%;
    background: radial-gradient(circle, rgba(0, 223, 216, 0.1) 0%, transparent 60%);
    transform: translate(-50%, -50%) scale(0);
    opacity: 0;
    transition: transform 0.6s ease-out, opacity 0.6s ease-out;
    pointer-events: none;
    z-index: 0;
}

.ripple-effect:hover::after {
    transform: translate(-50%, -50%) scale(1);
    opacity: 1;
}

.glass-card > * {
    position: relative;
    z-index: 1;
}

/* =========================================
   按钮与波浪过渡效果 (Gradient Wave Transitions)
   ========================================= */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 32px;
    font-size: 1.05rem;
    font-weight: 600;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
    position: relative;
    overflow: hidden;
    border: none;
    z-index: 1;
}

.btn-primary {
    color: #fff !important;
    background: var(--btn-gradient);
    background-size: 200% auto;
    box-shadow: 0 4px 15px rgba(121, 40, 202, 0.4);
}

.btn-primary:hover {
    background-position: right center;
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 223, 216, 0.5);
}

.btn-glass {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border-glass);
    color: var(--text-main) !important;
}

.btn-glass:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--accent-cyan);
    transform: translateY(-2px);
}

.btn-sm {
    padding: 10px 24px;
    font-size: 0.95rem;
}

/* =========================================
   导航栏 (Navbar)
   ========================================= */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    background: var(--bg-nav);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border-glass);
    transition: background 0.3s, box-shadow 0.3s;
    padding: 1rem 0;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: -0.05em;
}

.logo span {
    background: var(--btn-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-links a {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-muted);
    position: relative;
}

.nav-links a:hover {
    color: var(--text-main);
}

.nav-links a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: -4px;
    left: 0;
    background: var(--btn-gradient);
    transition: width 0.3s ease;
}

.nav-links a:hover::after {
    width: 100%;
}

.highlight-link {
    color: var(--accent-cyan) !important;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 1rem;
}

/* 精致透明化昼夜按钮 */
.theme-toggle {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-glass);
    color: var(--text-main);
    width: 38px;
    height: 38px;
    border-radius: 10px; /* 极客风方圆角 */
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    overflow: hidden;
    position: relative;
}

.theme-toggle:hover {
    border-color: var(--accent-cyan);
    background: rgba(0, 223, 216, 0.1);
}

.theme-toggle svg {
    position: absolute;
    transition: transform 0.4s cubic-bezier(0.68, -0.55, 0.27, 1.55), opacity 0.3s ease;
}

[data-theme="dark"] .sun-icon { transform: translateY(0); opacity: 1; }
[data-theme="dark"] .moon-icon { transform: translateY(30px); opacity: 0; }
:root:not([data-theme="dark"]) .sun-icon { transform: translateY(-30px); opacity: 0; }
:root:not([data-theme="dark"]) .moon-icon { transform: translateY(0); opacity: 1; }

/* 移动端菜单开关 */
.nav-toggle-label {
    display: none;
    cursor: pointer;
    color: var(--text-main);
}

/* =========================================
   主视觉区 (Hero & Fluid Aurora Background)
   ========================================= */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding-top: 5rem;
    position: relative;
    overflow: hidden;
}

/* 动态流体极光背景 (CSS Fluid WebGL-like Effect) */
.fluid-bg {
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 50% 50%, rgba(121, 40, 202, 0.15) 0%, transparent 40%),
                radial-gradient(circle at 80% 20%, rgba(0, 223, 216, 0.1) 0%, transparent 30%);
    z-index: 0;
    animation: rotate 30s linear infinite;
    pointer-events: none;
}

.fluid-bg::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 20% 80%, rgba(121, 40, 202, 0.1) 0%, transparent 40%);
    animation: rotate 40s linear infinite reverse;
}

@keyframes rotate {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.headline {
    font-size: 4rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    line-height: 1.1;
    letter-spacing: -0.03em;
    background: linear-gradient(to right, #ffffff, #a1a1aa);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

[data-theme="light"] .headline {
    background: linear-gradient(to right, #000000, #52525b);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.sub-headline {
    font-size: 1.2rem;
    color: var(--text-muted);
    max-width: 650px;
    margin: 0 auto 3rem;
}

.hero-actions {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
}

.floating-meters {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    pointer-events: none;
    z-index: -1;
}

.meter-box {
    position: absolute;
    background: rgba(20, 20, 25, 0.5);
    backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.05);
    padding: 1rem 1.5rem;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    animation: float 6s ease-in-out infinite;
}

.meter-box:nth-child(1) {
    top: 20%;
    left: 0;
    animation-delay: 0s;
    border-left: 2px solid var(--accent-cyan);
}

.meter-box:nth-child(2) {
    bottom: 20%;
    right: 0;
    animation-delay: 3s;
    border-left: 2px solid var(--accent-violet);
}

.meter-label {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 700;
    letter-spacing: 0.1em;
}

.meter-value {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--text-main);
    line-height: 1.2;
}

.meter-value small {
    font-size: 0.9rem;
    color: var(--text-muted);
    font-weight: 400;
    margin-left: 4px;
}

@keyframes float {
    0% { transform: translateY(0px); }
    50% { transform: translateY(-20px); }
    100% { transform: translateY(0px); }
}

/* =========================================
   核心优势 & 场景
   ========================================= */
.feature-grid, .scenario-grid, .pricing-grid, .review-grid {
    display: grid;
    gap: 2rem;
}

.feature-grid {
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.icon-wrapper {
    width: 56px;
    height: 56px;
    background: rgba(121, 40, 202, 0.1);
    color: var(--accent-cyan);
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
    border: 1px solid rgba(0, 223, 216, 0.1);
}

.feature-card h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

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

.scenario-grid {
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
}

.scenario-card h3 {
    font-size: 1.6rem;
    margin-bottom: 1rem;
    font-weight: 800;
}

.scenario-card p {
    color: var(--text-muted);
    margin-bottom: 2rem;
    font-size: 1rem;
}

/* =========================================
   套餐价格 (Pricing with Iridescent Borders)
   ========================================= */
.pricing-grid {
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    align-items: center;
}

.pricing-card {
    text-align: left;
    display: flex;
    flex-direction: column;
    height: 100%;
}

.pricing-card.popular {
    transform: scale(1.05);
    background: var(--bg-popular-card);
    z-index: 1;
}

.pricing-card.popular:hover {
    transform: scale(1.05) translateY(-8px);
}

/* 超细幻彩边框 (Ultra-fine iridescent borders) */
.iridescent-border {
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    border-radius: 16px;
    padding: 1px;
    background: var(--btn-gradient);
    -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    -webkit-mask-composite: xor;
    mask-composite: exclude;
    pointer-events: none;
}

.badge {
    position: absolute;
    top: -14px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--btn-gradient);
    color: white;
    padding: 6px 16px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 700;
    box-shadow: 0 4px 10px rgba(121, 40, 202, 0.3);
}

.pricing-card h3 {
    font-size: 1.25rem;
    color: var(--text-main);
    margin-bottom: 0.5rem;
}

.price {
    font-size: 3rem;
    font-weight: 800;
    color: var(--text-main);
    margin-bottom: 2rem;
    letter-spacing: -0.05em;
}

.price span {
    font-size: 1.1rem;
    color: var(--text-muted);
    font-weight: 500;
}

.plan-features {
    margin-bottom: 2.5rem;
    flex-grow: 1;
}

.plan-features li {
    padding: 12px 0;
    border-bottom: 1px solid var(--border-glass);
    color: var(--text-muted);
    font-size: 0.95rem;
    display: flex;
    align-items: center;
}

.plan-features li:last-child {
    border-bottom: none;
}

.plan-features li::before {
    content: "✦"; /* Modern tech bullet instead of basic check */
    color: var(--accent-cyan);
    margin-right: 12px;
    font-size: 1.1rem;
}

.pricing-card .btn {
    width: 100%;
}

/* =========================================
   评论与FAQ
   ========================================= */
.review-grid {
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.stars {
    color: var(--accent-cyan);
    font-size: 1.2rem;
    margin-bottom: 1.5rem;
    letter-spacing: 2px;
}

.review-card p {
    font-size: 1rem;
    color: var(--text-muted);
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

.author {
    font-weight: 700;
    color: var(--text-main);
    font-size: 0.9rem;
}

.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    margin-bottom: 1.5rem;
    background: var(--bg-card);
    border: 1px solid var(--border-glass);
    border-radius: 12px;
    padding: 1.5rem 2rem;
}

.faq-item h4 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: var(--text-main);
    font-weight: 600;
}

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

/* =========================================
   Footer
   ========================================= */
.footer {
    border-top: 1px solid var(--border-glass);
    padding: 4rem 0 3rem;
    text-align: center;
    background: rgba(9, 9, 11, 0.8);
    position: relative;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 3rem;
    flex-wrap: wrap;
    margin-bottom: 2rem;
}

.footer-links a {
    color: var(--text-muted);
    font-size: 0.95rem;
    font-weight: 500;
}

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

.copyright {
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* =========================================
   响应式 (Media Queries)
   ========================================= */
@media (max-width: 992px) {
    .headline { font-size: 3rem; }
    .floating-meters { display: none; } /* Hide floating elements on smaller screens */
}

@media (max-width: 768px) {
    .nav-toggle-label {
        display: block;
    }
    
    .nav-links {
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: var(--bg-nav-scroll);
        backdrop-filter: blur(20px);
        flex-direction: column;
        gap: 0;
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s ease-out;
        border-bottom: 1px solid transparent;
    }
    
    .nav-toggle:checked ~ .nav-links {
        max-height: 400px;
        border-bottom-color: var(--border-glass);
    }
    
    .nav-links li {
        width: 100%;
        text-align: center;
    }
    
    .nav-links a {
        display: block;
        padding: 15px 0;
        font-size: 1.1rem;
    }
    
    .nav-links a::after { display: none; }
    
    .headline { font-size: 2.2rem; }
    .sub-headline { font-size: 1rem; }
    
    .hero-actions {
        flex-direction: column;
    }
    
    .pricing-card.popular {
        transform: scale(1);
    }
    
    .pricing-card.popular:hover {
        transform: translateY(-8px);
    }
    
    .btn {
        padding: 16px 20px; 
    }
}