/* Seekho Learn — clean, fast, mobile-first stylesheet. No external assets. */

:root {
  --primary: #1d4ed8;
  --primary-dark: #1e40af;
  --accent: #f59e0b;
  --ink: #1f2937;
  --muted: #6b7280;
  --bg: #ffffff;
  --soft: #f8fafc;
  --border: #e5e7eb;
  --radius: 10px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.75;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
}

.container { max-width: 920px; margin: 0 auto; padding: 0 1.25rem; }

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

img, svg { max-width: 100%; height: auto; }

/* ---------- Header ---------- */
.site-header {
  background: #fff;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 50;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 0.85rem;
  padding-bottom: 0.85rem;
  gap: 1rem;
  flex-wrap: wrap;
}
.site-name {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--ink);
  letter-spacing: -0.02em;
}
.site-name:hover { text-decoration: none; color: var(--primary); }
.site-name .dot { color: var(--accent); }
.site-nav { display: flex; gap: 1.25rem; flex-wrap: wrap; }
.site-nav a { color: var(--muted); font-weight: 600; font-size: 0.95rem; }
.site-nav a:hover, .site-nav a.active { color: var(--primary); text-decoration: none; }

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(135deg, #1e3a8a 0%, #1d4ed8 60%, #3b82f6 100%);
  color: #fff;
  padding: 3.5rem 0 3rem;
  text-align: center;
}
.hero h1 { font-size: 2.4rem; line-height: 1.2; letter-spacing: -0.02em; margin-bottom: 0.5rem; }
.hero .tagline { font-size: 1.2rem; color: #dbeafe; font-weight: 600; margin-bottom: 1rem; }
.hero p.intro { max-width: 640px; margin: 0 auto; color: #e0e7ff; font-size: 1.02rem; }

/* ---------- Sections ---------- */
.section { padding: 2.5rem 0; }
.section-title { font-size: 1.6rem; letter-spacing: -0.01em; margin-bottom: 0.35rem; }
.section-sub { color: var(--muted); margin-bottom: 1.75rem; }

/* ---------- Article grid ---------- */
.article-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: 1.25rem;
}
.card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.35rem 1.25rem;
  background: #fff;
  display: flex;
  flex-direction: column;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.card:hover { transform: translateY(-3px); box-shadow: 0 10px 24px rgba(15, 23, 42, 0.08); }
.card h3 { font-size: 1.08rem; line-height: 1.45; margin-bottom: 0.5rem; }
.card h3 a { color: var(--ink); }
.card h3 a:hover { color: var(--primary); text-decoration: none; }
.card p { color: var(--muted); font-size: 0.94rem; flex: 1; }
.card .read-more { margin-top: 0.9rem; font-weight: 700; font-size: 0.92rem; }

/* ---------- Prose (articles & pages) ---------- */
.prose { max-width: 760px; }
.prose h1 { font-size: 2rem; line-height: 1.3; letter-spacing: -0.02em; margin-bottom: 0.75rem; }
.prose h2 { font-size: 1.45rem; margin: 2rem 0 0.75rem; letter-spacing: -0.01em; }
.prose h3 { font-size: 1.15rem; margin: 1.5rem 0 0.5rem; }
.prose p { margin-bottom: 1.1rem; }
.prose ul, .prose ol { margin: 0 0 1.25rem 1.4rem; }
.prose li { margin-bottom: 0.5rem; }
.prose blockquote {
  border-left: 4px solid var(--accent);
  background: var(--soft);
  padding: 0.9rem 1.1rem;
  border-radius: 0 8px 8px 0;
  margin: 1.25rem 0;
  color: #374151;
}
.prose .meta { color: var(--muted); font-size: 0.9rem; margin-bottom: 1.5rem; }
.author-box {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--soft);
  padding: 1.1rem 1.25rem;
  margin-top: 2.25rem;
  font-size: 0.94rem;
  color: #4b5563;
}
.author-box strong { color: var(--ink); }

/* ---------- Page hero (inner pages) ---------- */
.page-hero { background: var(--soft); border-bottom: 1px solid var(--border); padding: 2.25rem 0; }
.page-hero h1 { font-size: 2rem; letter-spacing: -0.02em; }
.page-hero p { color: var(--muted); max-width: 640px; }

/* ---------- Forms ---------- */
.contact-form { max-width: 560px; }
.field { margin-bottom: 1.1rem; }
.field label { display: block; font-weight: 600; margin-bottom: 0.35rem; font-size: 0.95rem; }
.field input, .field textarea {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.7rem 0.9rem;
  font: inherit;
  color: var(--ink);
}
.field input:focus, .field textarea:focus { outline: 2px solid var(--primary); border-color: var(--primary); }
.btn {
  display: inline-block;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 0.75rem 1.6rem;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}
.btn:hover { background: var(--primary-dark); }

/* ---------- Footer ---------- */
.site-footer { background: #111827; color: #9ca3af; padding: 2rem 0; margin-top: 3rem; font-size: 0.92rem; }
.site-footer .container { display: flex; justify-content: space-between; align-items: center; gap: 1rem; flex-wrap: wrap; }
.footer-nav { display: flex; gap: 1.1rem; flex-wrap: wrap; }
.footer-nav a { color: #d1d5db; }
.footer-nav a:hover { color: #fff; }

/* ---------- Responsive ---------- */
@media (max-width: 640px) {
  body { font-size: 16px; }
  .hero { padding: 2.5rem 0 2.25rem; }
  .hero h1 { font-size: 1.8rem; }
  .prose h1 { font-size: 1.6rem; }
  .header-inner { flex-direction: column; align-items: flex-start; }
  .site-footer .container { flex-direction: column; align-items: flex-start; }
}

/* ===== QA fix 2026-10-02: article-page element + missing class styles ===== */
header:not(.site-header) { background: #fff; border-bottom: 1px solid var(--border); padding: 16px 20px; }
header:not(.site-header) nav { margin-top: 10px; display: flex; flex-wrap: wrap; gap: 6px 18px; }
header:not(.site-header) nav a { color: var(--muted); font-size: 0.95rem; }
header:not(.site-header) nav a:hover { color: var(--primary); }
footer:not(.site-footer) { background: #111827; color: #9ca3af; padding: 2rem 20px; margin-top: 3rem; font-size: 0.92rem; }
footer:not(.site-footer) nav { margin-top: 10px; display: flex; flex-wrap: wrap; gap: 6px 16px; }
footer:not(.site-footer) nav a { color: #d1d5db; }
article:not(.card) { max-width: 920px; margin: 0 auto; padding: 2.5rem 1.25rem 1rem; }
.bio { background: var(--soft); border: 1px solid var(--border); border-radius: var(--radius); padding: 1rem 1.2rem; margin: 2.2rem 0 1rem; font-size: 0.95rem; color: var(--muted); }

/* ---------- Brand lockup ---------- */
.brand { display: inline-flex; align-items: center; gap: 0.6rem; }
.brand:hover { text-decoration: none; }
.brand-logo { width: 38px; height: 38px; display: block; flex: none; }
@media (max-width: 600px) { .brand-logo { width: 32px; height: 32px; } }

/* ---------- 404 page ---------- */
.error-wrap { text-align: center; padding: 4rem 1.25rem 5rem; }
.error-wrap .error-logo { width: 96px; height: 96px; margin-bottom: 1.25rem; }
.error-code { font-size: 4.5rem; font-weight: 800; color: var(--primary); line-height: 1; margin-bottom: 0.5rem; }
.error-wrap h1 { font-size: 1.75rem; margin-bottom: 0.75rem; }
.error-wrap p { color: var(--muted); max-width: 420px; margin: 0 auto 1.75rem; }
.btn-home { display: inline-block; background: var(--primary); color: #fff; font-weight: 700;
  padding: 0.75rem 1.75rem; border-radius: var(--radius); }
.btn-home:hover { background: var(--primary-dark); color: #fff; text-decoration: none; }

/* Article header logo lockup (QA 2026-10-02) */
header:not(.site-header) .site-name a { display: inline-flex; align-items: center; gap: .55rem; }
header:not(.site-header) .brand-logo { width: 32px; height: 32px; }