@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@300;400;500;700;900&family=Outfit:wght@300;400;500;700;900&display=swap');

:root {
    /* Brand Theme Colors */
    --color-brand: #415C7B;      /* 杀青 (Slate Blue) */
    --color-accent: #DED7CD;     /* 粉棕 (Pinkish Brown/Beige) */
    
    --color-brand-light: #eff3f6;
    --color-brand-dark: #2a3d54;
    --color-bg-body: #faf9f7;     /* Soft elegant light background */
    --color-card-bg: #ffffff;
    --color-text-main: #2d3748;
    --color-text-muted: #718096;
    
    --border-radius: 16px;
    --transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    --shadow-soft: 0 10px 30px rgba(65, 92, 123, 0.04);
    --shadow-hover: 0 20px 40px rgba(65, 92, 123, 0.08);
}

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

body {
    font-family: 'Outfit', 'Noto Sans SC', sans-serif;
    background-color: var(--color-bg-body);
    color: var(--color-text-main);
    line-height: 1.7;
    overflow-x: hidden;
}

/* --- Scrollbar --- */
::-webkit-scrollbar {
    width: 8px;
}
::-webkit-scrollbar-track {
    background: var(--color-bg-body);
}
::-webkit-scrollbar-thumb {
    background: var(--color-accent);
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--color-brand);
}

/* --- Header / Navbar --- */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(250, 249, 247, 0.85);
    backdrop-filter: blur(15px);
    -webkit-backdrop-filter: blur(15px);
    z-index: 1000;
    border-bottom: 1px solid rgba(65, 92, 123, 0.06);
    transition: var(--transition);
}
.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 18px 24px;
}
.logo {
    font-family: 'Outfit', sans-serif;
    font-size: 1.6rem;
    font-weight: 900;
    color: var(--color-brand);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
}
.logo span {
    font-size: 1rem;
    background: var(--color-accent);
    color: var(--color-brand-dark);
    padding: 2px 8px;
    border-radius: 20px;
    font-weight: 700;
}
.nav-links {
    display: flex;
    gap: 32px;
    list-style: none;
}
.nav-links a {
    color: var(--color-text-main);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    position: relative;
    transition: var(--transition);
}
.nav-links a:hover {
    color: var(--color-brand);
}
.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -6px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--color-brand);
    transition: var(--transition);
}
.nav-links a:hover::after {
    width: 100%;
}

/* --- Hero Section --- */
.hero {
    position: relative;
    padding: 160px 20px 100px;
    min-height: 90vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: radial-gradient(circle at 80% 20%, rgba(222, 215, 205, 0.4) 0%, rgba(250, 249, 247, 1) 70%);
    overflow: hidden;
}
#particles-canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
    pointer-events: none;
}
.hero-container {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    position: relative;
    z-index: 2;
}
.hero-badge {
    display: inline-block;
    background: var(--color-brand-light);
    color: var(--color-brand);
    padding: 6px 16px;
    border-radius: 30px;
    font-size: 0.85rem;
    font-weight: 700;
    margin-bottom: 24px;
    letter-spacing: 1px;
    border: 1px solid rgba(65, 92, 123, 0.1);
}
.hero-title {
    font-size: 3.6rem;
    font-weight: 900;
    color: var(--color-brand-dark);
    line-height: 1.25;
    margin-bottom: 24px;
    letter-spacing: -0.5px;
}
.hero-desc {
    font-size: 1.15rem;
    color: var(--color-text-muted);
    max-width: 600px;
    margin: 0 auto 40px;
}

/* --- Buttons --- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 16px 36px;
    border-radius: 30px;
    font-weight: 700;
    font-size: 1.05rem;
    text-decoration: none;
    transition: var(--transition);
    cursor: pointer;
    border: none;
}
.btn-primary {
    background: var(--color-brand);
    color: #ffffff;
    box-shadow: 0 8px 24px rgba(65, 92, 123, 0.25);
}
.btn-primary:hover {
    background: var(--color-brand-dark);
    transform: translateY(-2px);
    box-shadow: 0 12px 30px rgba(65, 92, 123, 0.35);
}
.btn-secondary {
    background: var(--color-accent);
    color: var(--color-brand-dark);
    box-shadow: 0 8px 24px rgba(222, 215, 205, 0.3);
}
.btn-secondary:hover {
    background: var(--color-brand-light);
    color: var(--color-brand-dark);
    transform: translateY(-2px);
}

/* --- Section Layouts --- */
.section {
    padding: 100px 20px;
    max-width: 1200px;
    margin: 0 auto;
}
.section-header {
    text-align: center;
    max-width: 700px;
    margin: 0 auto 60px;
}
.section-header h2 {
    font-size: 2.4rem;
    font-weight: 800;
    color: var(--color-brand-dark);
    margin-bottom: 16px;
}
.section-header p {
    color: var(--color-text-muted);
    font-size: 1.05rem;
}

/* --- Tutorial Cards --- */
.tutorial-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}
.tutorial-card {
    background: var(--color-card-bg);
    border-radius: var(--border-radius);
    padding: 36px 30px;
    box-shadow: var(--shadow-soft);
    border: 1px solid rgba(65, 92, 123, 0.04);
    position: relative;
    transition: var(--transition);
}
.tutorial-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-hover);
}
.step-num {
    position: absolute;
    top: 20px;
    right: 25px;
    font-family: 'Outfit', sans-serif;
    font-size: 2.8rem;
    font-weight: 900;
    color: rgba(222, 215, 205, 0.4);
    line-height: 1;
}
.tutorial-card i {
    font-size: 2.2rem;
    color: var(--color-brand);
    margin-bottom: 24px;
}
.tutorial-card h3 {
    font-size: 1.3rem;
    margin-bottom: 12px;
    color: var(--color-brand-dark);
}
.tutorial-card p {
    font-size: 0.95rem;
    color: var(--color-text-muted);
}

/* --- Pricing Cards --- */
.pricing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px;
    justify-content: center;
}
.pricing-card {
    background: var(--color-card-bg);
    border-radius: var(--border-radius);
    padding: 40px 30px;
    box-shadow: var(--shadow-soft);
    border: 2px solid transparent;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
}
.pricing-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-hover);
}
.pricing-card.premium-card {
    border-color: var(--color-accent);
    position: relative;
}
.premium-tag {
    position: absolute;
    top: 20px;
    right: 30px;
    background: var(--color-brand);
    color: #ffffff;
    padding: 4px 12px;
    font-size: 0.75rem;
    font-weight: 700;
    border-radius: 20px;
}
.pricing-card h3 {
    font-size: 1.4rem;
    font-weight: 800;
    color: var(--color-brand-dark);
    margin-bottom: 20px;
}
.pricing-card .price {
    font-size: 3rem;
    font-weight: 900;
    color: var(--color-brand-dark);
    margin-bottom: 30px;
}
.pricing-card .price span {
    font-size: 1rem;
    font-weight: 500;
    color: var(--color-text-muted);
}
.pricing-features {
    list-style: none;
    margin-bottom: 35px;
    flex-grow: 1;
}
.pricing-features li {
    margin-bottom: 16px;
    font-size: 0.95rem;
    display: flex;
    align-items: center;
    gap: 12px;
}
.pricing-features li i {
    color: var(--color-brand);
    font-size: 1.1rem;
}
.pricing-features li.warning {
    margin-top: 25px;
    border-top: 1px dashed rgba(65, 92, 123, 0.1);
    padding-top: 15px;
    color: #e53e3e;
    font-size: 0.82rem;
    align-items: flex-start;
}
.pricing-features li.warning i {
    color: #e53e3e;
    margin-top: 3px;
}
.pricing-card .btn {
    width: 100%;
}

/* --- Knowledge / Articles --- */
.kb-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}
.kb-card {
    background: var(--color-card-bg);
    border-radius: var(--border-radius);
    padding: 30px;
    box-shadow: var(--shadow-soft);
    border: 1px solid rgba(65, 92, 123, 0.04);
    transition: var(--transition);
}
.kb-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}
.kb-card h4 {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--color-brand-dark);
    margin-bottom: 12px;
    line-height: 1.4;
}
.kb-card p {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-bottom: 20px;
}
.kb-card a {
    color: var(--color-brand);
    text-decoration: none;
    font-weight: 700;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.9rem;
}

/* --- About Us --- */
.about-section {
    background: var(--color-brand-light);
    border-radius: 24px;
    padding: 60px 40px;
    margin-top: 40px;
}
.about-content {
    max-width: 900px;
    margin: 0 auto;
    text-align: center;
}
.about-content h3 {
    font-size: 1.8rem;
    color: var(--color-brand-dark);
    margin-bottom: 20px;
}
.about-content p {
    color: var(--color-text-muted);
    margin-bottom: 30px;
}

/* --- FAQ Accordion --- */
.faq-container {
    max-width: 800px;
    margin: 0 auto;
}
.faq-item {
    background: var(--color-card-bg);
    border-radius: var(--border-radius);
    margin-bottom: 16px;
    box-shadow: var(--shadow-soft);
    border: 1px solid rgba(65, 92, 123, 0.04);
    overflow: hidden;
}
.faq-question {
    padding: 24px;
    font-weight: 700;
    color: var(--color-brand-dark);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: var(--transition);
}
.faq-question:hover {
    background: rgba(65, 92, 123, 0.02);
}
.faq-answer {
    padding: 0 24px;
    max-height: 0;
    overflow: hidden;
    transition: var(--transition);
    color: var(--color-text-muted);
}
.faq-item.active .faq-answer {
    padding: 0 24px 24px;
    max-height: 200px;
}
.faq-icon {
    font-size: 0.8rem;
    transition: var(--transition);
}
.faq-item.active .faq-icon {
    transform: rotate(180deg);
}

/* --- Reviews --- */
.reviews-section {
    background: linear-gradient(135deg, var(--color-brand-dark) 0%, var(--color-brand) 100%);
    color: #ffffff;
    padding: 80px 20px;
}
.reviews-section h2 {
    text-align: center;
    color: #ffffff;
    margin-bottom: 50px;
    font-size: 2.2rem;
    font-weight: 800;
}
.reviews-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px;
}
.review-card {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
    border-radius: var(--border-radius);
    padding: 30px;
    border: 1px solid rgba(255, 255, 255, 0.1);
}
.review-card p {
    font-style: italic;
    color: #e2e8f0;
    margin-bottom: 20px;
}
.review-card .author {
    font-weight: 700;
    color: var(--color-accent);
}

/* --- Footer --- */
.footer {
    background: #1a2530;
    color: #a0aec0;
    padding: 80px 20px 40px;
}
.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    border-bottom: 1px solid rgba(255,255,255,0.08);
    padding-bottom: 40px;
    margin-bottom: 40px;
}
.footer-logo {
    color: #ffffff;
    font-size: 1.5rem;
    font-weight: 800;
    text-decoration: none;
    margin-bottom: 20px;
    display: block;
}
.footer-logo span {
    color: var(--color-accent);
}
.footer-desc {
    font-size: 0.9rem;
    line-height: 1.6;
}
.footer-column h5 {
    color: #ffffff;
    font-size: 1.05rem;
    margin-bottom: 20px;
}
.footer-faq-list {
    list-style: none;
}
.footer-faq-list li {
    margin-bottom: 15px;
    font-size: 0.88rem;
}
.footer-faq-list strong {
    color: #ffffff;
    display: block;
    margin-bottom: 4px;
}
.footer-bottom {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
    font-size: 0.85rem;
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    .hero-title {
        font-size: 2.6rem;
    }
}

.hidden-card {
    display: none !important;
}