:root {
    /* Color Palette */
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary: #64748b;
    --accent: #0ea5e9;
    --background: #f8fafc;
    --surface: #ffffff;
    --text-main: #0f172a;
    --text-muted: #475569;
    --border: #e2e8f0;
    --white: #ffffff;
    
    /* Gradients */
    --grad-blue: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
    --grad-sky: linear-gradient(135deg, #0ea5e9 0%, #2563eb 100%);
    
    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 2rem;
    --space-lg: 4rem;
    --space-xl: 8rem;
    
    /* Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    
    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--background);
    color: var(--text-main);
    line-height: 1.6;
    overflow-x: hidden;
}

/* Layout */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-md);
}

section {
    padding: var(--space-lg) 0;
}

/* Typography */
h1, h2, h3 {
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: var(--space-sm);
}

h1 { font-size: clamp(2.5rem, 8vw, 4rem); }
h2 { font-size: clamp(1.75rem, 5vw, 2.5rem); text-align: center; margin-bottom: var(--space-lg); }
h3 { font-size: 1.5rem; }

p { color: var(--text-muted); margin-bottom: var(--space-sm); }

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.875rem 2rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
    border: none;
    font-size: 1.1rem;
}

.btn-primary {
    background: var(--grad-blue);
    color: var(--white);
    box-shadow: 0 4px 14px 0 rgba(37, 99, 235, 0.39);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.23);
    filter: brightness(1.1);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--primary);
    color: var(--primary);
}

.btn-outline:hover {
    background: var(--primary);
    color: var(--white);
}

/* Header */
header {
    padding: var(--space-sm) 0;
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(248, 250, 252, 0.8);
    backdrop-filter: blur(10px);
}

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

.nav-links {
    display: flex;
    gap: var(--space-md);
    list-style: none;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-muted);
    font-weight: 500;
    transition: color 0.3s;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 900;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
}

/* Hero Section */
.hero {
    padding: var(--space-xl) 0 var(--space-lg);
    text-align: center;
    position: relative;
    overflow: hidden;
    background: radial-gradient(circle at top right, #e0f2fe 0%, transparent 40%),
                radial-gradient(circle at bottom left, #dbeafe 0%, transparent 40%);
}

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

.cloud {
    position: absolute;
    background: white;
    filter: blur(40px);
    border-radius: 50%;
    opacity: 0.4;
    animation: float 20s infinite linear;
}

.cloud-1 { width: 300px; height: 100px; top: 10%; left: -10%; }
.cloud-2 { width: 400px; height: 150px; top: 50%; right: -10%; animation-delay: -5s; }
.cloud-3 { width: 200px; height: 80px; bottom: 10%; left: 20%; animation-delay: -10s; }

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

.hero-content {
    position: relative;
    z-index: 1;
}

.hero-badge {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: #dbeafe;
    color: var(--primary);
    border-radius: 100px;
    font-size: 0.875rem;
    font-weight: 700;
    margin-bottom: var(--space-md);
}

.hero p {
    font-size: 1.25rem;
    max-width: 600px;
    margin: 0 auto var(--space-md);
}

/* Features Section */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-md);
}

.feature-card {
    background: var(--surface);
    padding: var(--space-md);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    transition: all 0.3s ease;
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.feature-icon {
    width: 64px;
    height: 64px;
    background: #eff6ff;
    border-radius: 16px;
    margin: 0 auto var(--space-sm);
    display: flex;
    align-items: center;
    justify-content: center;
}

.feature-icon svg {
    width: 32px;
    height: 32px;
    color: var(--primary);
}

/* Pricing Section */
.pricing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-md);
    align-items: flex-end;
}

.pricing-card {
    background: var(--surface);
    padding: var(--space-md);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    position: relative;
    display: flex;
    flex-direction: column;
}

.pricing-card.featured {
    border-color: var(--primary);
    border-width: 2px;
    transform: scale(1.05);
    z-index: 10;
    box-shadow: var(--shadow-lg);
}

.badge-top {
    position: absolute;
    top: -12px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--grad-blue);
    color: var(--white);
    padding: 0.25rem 1rem;
    border-radius: 100px;
    font-size: 0.75rem;
    font-weight: 700;
}

.price {
    font-size: 3rem;
    font-weight: 800;
    margin: var(--space-sm) 0;
}

.price span {
    font-size: 1rem;
    color: var(--text-muted);
}

.pricing-features {
    list-style: none;
    margin: var(--space-md) 0;
    flex-grow: 1;
}

.pricing-features li {
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.95rem;
}

.pricing-features li::before {
    content: "✓";
    color: #10b981;
    font-weight: bold;
}

/* FAQ Section */
.faq-container {
    max-width: 800px;
    margin: 0 auto;
}

details {
    background: var(--surface);
    margin-bottom: var(--space-sm);
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
}

summary {
    padding: var(--space-sm) var(--space-md);
    font-weight: 600;
    cursor: pointer;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

summary::after {
    content: "+";
    font-size: 1.5rem;
    color: var(--primary);
    transition: transform 0.3s;
}

details[open] summary::after {
    transform: rotate(45deg);
}

.faq-content {
    padding: 0 var(--space-md) var(--space-sm);
    color: var(--text-muted);
}

/* Footer */
footer {
    background: var(--text-main);
    color: var(--white);
    padding: var(--space-lg) 0 var(--space-md);
    margin-top: var(--space-lg);
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--space-lg);
    margin-bottom: var(--space-lg);
}

.footer-logo {
    color: var(--white);
    font-size: 1.5rem;
    font-weight: 800;
    margin-bottom: var(--space-sm);
}

.footer-links h4 {
    margin-bottom: var(--space-sm);
}

.footer-links ul {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.5rem;
}

.footer-links a {
    color: #94a3b8;
    text-decoration: none;
    transition: color 0.3s;
}

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

.copyright {
    text-align: center;
    padding-top: var(--space-md);
    border-top: 1px solid #334155;
    color: #64748b;
    font-size: 0.875rem;
}

/* Responsive Adjustments */
@media (max-width: 768px) {
    .pricing-card.featured {
        transform: scale(1);
    }
    .hero {
        padding: var(--space-lg) 0;
    }
    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }
}

/* Shared inner pages */
.page-content { max-width: 800px; margin: 40px auto; padding: 0 20px; }
.page-content h1 { margin-bottom: 30px; text-align: left; font-size: clamp(1.8rem, 6vw, 2.5rem); }
.page-content section { padding: 20px 0; border-bottom: 1px solid #eee; }
.page-content h2 { text-align: left; margin-bottom: 15px; font-size: 1.5rem; }
.page-content ul { padding-left: 1.25rem; color: var(--text-muted); }
.breadcrumb { font-size: 0.875rem; color: var(--text-muted); margin-bottom: 20px; }
.breadcrumb a { color: var(--primary); text-decoration: none; }
.breadcrumb span { margin: 0 6px; }
.footer-friends { margin-top: 10px; font-size: 0.9em; opacity: 0.8; }
.footer-friends a { color: inherit; text-decoration: none; margin: 0 8px; }
.sitemap-list { list-style: none; padding: 0; }
.sitemap-item { margin-bottom: 20px; padding: 20px; background: #fff; border-radius: 12px; border: 1px solid #eee; }
.sitemap-item h3 { margin-bottom: 10px; color: #2563eb; }
.sitemap-item p { font-size: 0.9rem; margin: 0; }
.sitemap-item a { text-decoration: none; color: inherit; display: block; }
.sitemap-item:hover { border-color: #2563eb; box-shadow: 0 4px 12px rgba(0,0,0,0.05); }
.not-found { text-align: center; padding: 80px 20px; }
.not-found h1 { font-size: clamp(2rem, 6vw, 3rem); }
.logo, .nav-links a, .nav-wrapper .btn { white-space: nowrap; }
@media (max-width: 640px) {
    .container { padding: 0 16px; }
    .nav-links { display: none; }
    .nav-wrapper .btn { padding: 0.5rem 1rem; font-size: 0.95rem; }
}

/* Articles */
.article-content { max-width: 850px; margin: 40px auto; padding: 0 20px; line-height: 1.8; color: #334155; }
.article-content h1 { font-size: clamp(1.7rem, 5vw, 2.2rem); color: #0f172a; margin-bottom: 20px; text-align: left; }
.article-content h2 { font-size: 1.6rem; color: #1e293b; margin: 36px 0 15px; border-left: 4px solid #2563eb; padding-left: 15px; text-align: left; }
.article-content h3 { font-size: 1.2rem; color: #1e293b; margin: 24px 0 10px; }
.article-content p, .article-content li { margin-bottom: 12px; color: #334155; }
.article-content ol, .article-content ul { padding-left: 1.4rem; margin-bottom: 20px; }
.article-content strong { color: #0f172a; }
.article-content .meta { color: #64748b; font-size: 0.9rem; margin-bottom: 30px; }
.article-content a { color: #2563eb; }
.article-content .btn-primary { color: #fff; }
.internal-link { color: #2563eb; font-weight: 600; text-decoration: underline; }
.cta-box { background: #f1f5f9; padding: 25px; border-radius: 12px; border: 1px solid #e2e8f0; margin: 30px 0; text-align: center; }
.summary-box { background: #eff6ff; border: 1px solid #bfdbfe; border-radius: 12px; padding: 18px 22px; margin: 0 0 30px; }
.summary-box p:last-child, .summary-box ul:last-child { margin-bottom: 0; }
.table-wrap { overflow-x: auto; margin: 20px 0; }
.article-content table { width: 100%; border-collapse: collapse; font-size: 0.95rem; min-width: 520px; }
.article-content th, .article-content td { border: 1px solid #e2e8f0; padding: 10px 12px; text-align: left; vertical-align: top; }
.article-content th { background: #f8fafc; color: #0f172a; }
.related { margin-top: 40px; padding-top: 20px; border-top: 1px solid #e2e8f0; }
.guides-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: var(--space-md); }
.guide-card { display: block; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-md); padding: var(--space-md); text-decoration: none; color: inherit; transition: border-color .2s, box-shadow .2s; }
.guide-card:hover { border-color: var(--primary); box-shadow: var(--shadow-md); }
.guide-card h3 { font-size: 1.2rem; color: var(--primary); }
.guide-card p { margin: 0; }