:root {
  --primary: #4361ee;
  --primary-dark: #3451d1;
  --primary-light: #eef0fd;
  --accent: #43aa8b;
  --accent-light: #e8f7f3;
  --text: #1e293b;
  --text-muted: #64748b;
  --bg: #f8fafc;
  --surface: #ffffff;
  --border: #e2e8f0;
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 4px 24px rgba(0,0,0,.08);
  --shadow-lg: 0 8px 48px rgba(0,0,0,.12);
  --transition: .2s ease;
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body { font-family: 'Inter', -apple-system, sans-serif; font-size: 16px; color: var(--text); background: var(--bg); line-height: 1.6; }
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; height: auto; display: block; }
ul { list-style: none; }

/* Container */
.sk-container { max-width: 1120px; margin: 0 auto; padding: 0 20px; }

/* Header */
.sk-header { background: #fff; border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 100; }
.sk-header .sk-container { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.sk-logo { display: flex; align-items: center; gap: 8px; font-size: 20px; font-weight: 700; color: var(--text); }
.sk-logo:hover { text-decoration: none; }
.sk-logo-icon { font-size: 24px; }
.sk-logo-text strong { color: var(--primary); }
.sk-nav { display: flex; align-items: center; gap: 24px; font-size: 14px; font-weight: 500; }
.sk-nav a { color: var(--text-muted); }
.sk-nav a:hover { color: var(--primary); text-decoration: none; }
.sk-btn-nav { background: var(--primary); color: #fff !important; padding: 8px 18px; border-radius: 8px; }
.sk-btn-nav:hover { background: var(--primary-dark); }

/* Buttons */
.sk-btn { display: inline-flex; align-items: center; gap: 8px; padding: 14px 28px; border-radius: 10px; font-weight: 600; font-size: 15px; cursor: pointer; transition: all var(--transition); border: none; }
.sk-btn-primary { background: var(--primary); color: #fff; }
.sk-btn-primary:hover { background: var(--primary-dark); transform: translateY(-1px); box-shadow: 0 8px 24px rgba(67,97,238,.3); text-decoration: none; color: #fff; }
.sk-btn-secondary { background: var(--surface); color: var(--primary); border: 2px solid var(--primary); }
.sk-btn-secondary:hover { background: var(--primary-light); text-decoration: none; }
.sk-btn-lg { padding: 18px 36px; font-size: 17px; border-radius: 12px; }

/* Hero */
.sk-hero { background: linear-gradient(135deg, #f0f3ff 0%, #e8f7f3 100%); padding: 80px 0 60px; text-align: center; }
.sk-hero-badge { display: inline-flex; align-items: center; gap: 6px; background: var(--primary-light); color: var(--primary); padding: 6px 14px; border-radius: 20px; font-size: 13px; font-weight: 600; margin-bottom: 24px; }
.sk-hero h1 { font-size: clamp(32px, 5vw, 56px); font-weight: 800; line-height: 1.15; color: var(--text); margin-bottom: 20px; letter-spacing: -.5px; }
.sk-hero h1 span { color: var(--primary); }
.sk-hero p.lead { font-size: clamp(16px, 2vw, 19px); color: var(--text-muted); max-width: 600px; margin: 0 auto 36px; }
.sk-hero-ctas { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.sk-hero-stats { display: flex; gap: 40px; justify-content: center; margin-top: 48px; flex-wrap: wrap; }
.sk-hero-stat { text-align: center; }
.sk-hero-stat-n { font-size: 28px; font-weight: 800; color: var(--primary); }
.sk-hero-stat-l { font-size: 13px; color: var(--text-muted); margin-top: 2px; }

/* Features */
.sk-section { padding: 72px 0; }
.sk-section-title { text-align: center; font-size: clamp(24px, 3vw, 36px); font-weight: 700; margin-bottom: 12px; }
.sk-section-subtitle { text-align: center; color: var(--text-muted); font-size: 17px; max-width: 560px; margin: 0 auto 48px; }
.sk-features-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 24px; }
.sk-feature-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 28px; transition: all var(--transition); }
.sk-feature-card:hover { box-shadow: var(--shadow); transform: translateY(-2px); }
.sk-feature-icon { font-size: 36px; margin-bottom: 16px; }
.sk-feature-card h3 { font-size: 17px; font-weight: 700; margin-bottom: 8px; }
.sk-feature-card p { color: var(--text-muted); font-size: 14px; }

/* Steps */
.sk-steps { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 32px; }
.sk-step { text-align: center; }
.sk-step-n { width: 48px; height: 48px; background: var(--primary); color: #fff; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-weight: 800; font-size: 18px; margin: 0 auto 16px; }
.sk-step h3 { font-size: 16px; font-weight: 700; margin-bottom: 8px; }
.sk-step p { font-size: 14px; color: var(--text-muted); }

/* CTA band */
.sk-cta-band { background: linear-gradient(135deg, var(--primary) 0%, #6c63ff 100%); color: #fff; padding: 72px 0; text-align: center; }
.sk-cta-band h2 { font-size: clamp(24px, 3vw, 40px); font-weight: 800; margin-bottom: 12px; }
.sk-cta-band p { font-size: 17px; opacity: .85; margin-bottom: 32px; }
.sk-btn-white { background: #fff; color: var(--primary); }
.sk-btn-white:hover { background: #f0f3ff; text-decoration: none; color: var(--primary); }

/* Category cards */
.sk-cat-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 16px; }
.sk-cat-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 20px; display: flex; align-items: center; gap: 14px; transition: all var(--transition); text-decoration: none; color: var(--text); }
.sk-cat-card:hover { box-shadow: var(--shadow); transform: translateX(2px); text-decoration: none; color: var(--text); }
.sk-cat-icon { font-size: 28px; flex-shrink: 0; }
.sk-cat-info h3 { font-size: 14px; font-weight: 600; margin-bottom: 2px; }
.sk-cat-info p { font-size: 12px; color: var(--text-muted); }

/* Page cards */
.sk-pages-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 16px; }
.sk-page-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 20px 24px; transition: all var(--transition); }
.sk-page-card:hover { box-shadow: var(--shadow); transform: translateY(-1px); }
.sk-page-card h3 { font-size: 15px; font-weight: 600; margin-bottom: 6px; }
.sk-page-card h3 a { color: var(--text); }
.sk-page-card h3 a:hover { color: var(--primary); text-decoration: none; }
.sk-page-card p { font-size: 13px; color: var(--text-muted); line-height: 1.5; }

/* Article page */
.sk-article { max-width: 760px; margin: 0 auto; padding: 40px 20px 80px; }
.sk-breadcrumb { font-size: 13px; color: var(--text-muted); margin-bottom: 24px; }
.sk-breadcrumb a { color: var(--text-muted); }
.sk-breadcrumb a:hover { color: var(--primary); }
.sk-article h1 { font-size: clamp(24px, 4vw, 38px); font-weight: 800; line-height: 1.2; margin-bottom: 16px; }
.sk-article .sk-article-meta { font-size: 13px; color: var(--text-muted); margin-bottom: 32px; padding-bottom: 24px; border-bottom: 1px solid var(--border); }
.sk-article-body h2 { font-size: 22px; font-weight: 700; margin: 36px 0 12px; color: var(--text); }
.sk-article-body p { margin-bottom: 16px; color: var(--text); line-height: 1.7; }
.sk-article-body ul, .sk-article-body ol { margin: 16px 0 16px 24px; }
.sk-article-body li { margin-bottom: 8px; color: var(--text); }
.sk-article-body ul { list-style: disc; }
.sk-article-body ol { list-style: decimal; }

/* Intro box */
.sk-intro-box { background: var(--primary-light); border-left: 4px solid var(--primary); border-radius: 0 var(--radius-sm) var(--radius-sm) 0; padding: 20px 24px; margin-bottom: 32px; font-size: 16px; line-height: 1.6; }

/* FAQ */
.sk-faq { margin-top: 48px; }
.sk-faq h2 { font-size: 22px; font-weight: 700; margin-bottom: 20px; }
.sk-faq-item { border: 1px solid var(--border); border-radius: var(--radius-sm); margin-bottom: 10px; overflow: hidden; }
.sk-faq-q { padding: 16px 20px; font-weight: 600; font-size: 15px; cursor: pointer; display: flex; justify-content: space-between; align-items: center; }
.sk-faq-q::after { content: '+'; font-size: 20px; font-weight: 400; color: var(--primary); flex-shrink: 0; }
.sk-faq-item.open .sk-faq-q::after { content: '−'; }
.sk-faq-a { padding: 0 20px; max-height: 0; overflow: hidden; transition: max-height .3s ease, padding .3s ease; font-size: 14px; color: var(--text-muted); line-height: 1.6; }
.sk-faq-item.open .sk-faq-a { max-height: 300px; padding: 0 20px 16px; }

/* Inline CTA */
.sk-inline-cta { background: linear-gradient(135deg, var(--primary-light) 0%, var(--accent-light) 100%); border-radius: var(--radius); padding: 32px; text-align: center; margin: 40px 0; }
.sk-inline-cta h3 { font-size: 20px; font-weight: 700; margin-bottom: 8px; }
.sk-inline-cta p { color: var(--text-muted); margin-bottom: 20px; }

/* Related */
.sk-related { margin-top: 48px; padding-top: 32px; border-top: 1px solid var(--border); }
.sk-related h2 { font-size: 20px; font-weight: 700; margin-bottom: 16px; }
.sk-related-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 12px; }
.sk-related-item { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 14px; font-size: 14px; font-weight: 500; color: var(--text); transition: all var(--transition); }
.sk-related-item:hover { border-color: var(--primary); color: var(--primary); text-decoration: none; }

/* Category page */
.sk-cat-hero { background: linear-gradient(135deg, #f0f3ff 0%, #e8f7f3 100%); padding: 48px 0 36px; }
.sk-cat-hero h1 { font-size: clamp(24px, 4vw, 40px); font-weight: 800; margin-bottom: 12px; }
.sk-cat-hero p { color: var(--text-muted); font-size: 16px; max-width: 600px; }

/* Bg variants */
.bg-white { background: #fff; }
.bg-light { background: var(--bg); }

/* Footer */
.sk-footer { background: #1e293b; color: #94a3b8; padding: 64px 0 32px; }
.sk-footer .sk-logo-text { color: #fff; }
.sk-footer-desc { font-size: 14px; max-width: 260px; }
.sk-footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 48px; margin-bottom: 48px; }
.sk-footer h4 { color: #fff; font-size: 14px; font-weight: 600; margin-bottom: 16px; }
.sk-footer ul li { margin-bottom: 8px; }
.sk-footer ul li a { color: #94a3b8; font-size: 14px; }
.sk-footer ul li a:hover { color: #fff; text-decoration: none; }
.sk-footer-bottom { border-top: 1px solid #334155; padding-top: 24px; font-size: 13px; }
.mb-2 { margin-bottom: 8px; }
.mt-3 { margin-top: 12px; }

/* Responsive */
@media (max-width: 768px) {
  .sk-nav a:not(.sk-btn-nav) { display: none; }
  .sk-footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
  .sk-hero { padding: 48px 0 36px; }
  .sk-section { padding: 48px 0; }
}
@media (max-width: 480px) {
  .sk-footer-grid { grid-template-columns: 1fr; }
}