:root {
  --navy: #0F172A;
  --navy2: #1E3A8A;
  --cyan: #06B6D4;
  --amber: #F59E0B;
  --txt: #FFFFFF;
  --txt2: #94A3B8;
  --card: rgba(30, 58, 138, 0.25);
  --line: rgba(148, 163, 184, 0.2);
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: 'Segoe UI', system-ui, Tahoma, sans-serif;
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy2) 50%, var(--navy) 100%);
  color: var(--txt);
  line-height: 1.65;
  min-height: 100vh;
}
.container { max-width: 760px; margin: 0 auto; padding: 2.5rem 1.25rem; }

.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(15, 23, 42, 0.95);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(8px);
}
.nav-inner {
  max-width: 1100px; margin: 0 auto; padding: 0.9rem 1.25rem;
  display: flex; align-items: center; gap: 1.4rem; flex-wrap: wrap;
}
.brand { font-weight: 700; color: var(--txt); text-decoration: none; letter-spacing: 0.4px; }
.nav-inner a { color: var(--txt2); text-decoration: none; font-weight: 500; }
.nav-inner a:hover { color: var(--cyan); }
.btn-cta {
  background: var(--amber); color: var(--navy) !important;
  padding: 0.45rem 0.9rem; border-radius: 6px; font-weight: 700;
}
.btn-cta:hover { filter: brightness(1.1); }

.hero { padding: 3rem 1.25rem 1rem; max-width: 760px; margin: 0 auto; }
.hero h1 { font-size: 2rem; margin-bottom: 0.75rem; }
.hero p { color: var(--txt2); }

.card {
  display: block; background: var(--card); border: 1px solid var(--line);
  border-radius: 10px; padding: 1.4rem; margin: 1.25rem auto; max-width: 760px;
  text-decoration: none; color: var(--txt);
}
.card:hover { border-color: var(--cyan); }
.card h2 { font-size: 1.25rem; color: var(--cyan); margin-bottom: 0.5rem; }
.card p { color: var(--txt2); font-size: 0.95rem; }
.card .date { display: block; margin-top: 0.7rem; font-size: 0.8rem; color: var(--txt2); }

.article-body h1 { font-size: 2.1rem; line-height: 1.25; margin-bottom: 0.8rem; }
.meta-line { color: var(--txt2); font-size: 0.9rem; font-style: italic; margin-bottom: 1.6rem; }
.article-body h2 {
  font-size: 1.45rem; color: var(--cyan);
  margin: 2.4rem 0 0.9rem; padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--line);
}
.article-body p { color: var(--txt2); margin-bottom: 1.1rem; }
.article-body ul, .article-body ol { color: var(--txt2); margin: 0 0 1.2rem 1.4rem; }
.article-body li { margin-bottom: 0.45rem; }
.article-body strong { color: var(--txt); }

.placeholder {
  border: 2px dashed var(--line); border-radius: 10px;
  padding: 2.2rem 1.2rem; margin: 1.6rem 0; text-align: center;
  color: var(--txt2); font-size: 0.9rem; background: rgba(15, 23, 42, 0.4);
}
.callout {
  background: var(--card); border-left: 4px solid var(--amber);
  border-radius: 0 8px 8px 0; padding: 1.1rem 1.3rem; margin: 1.5rem 0;
}
.callout.info { border-left-color: var(--cyan); }
.callout strong { color: var(--amber); }
.callout.info strong { color: var(--cyan); }
.callout p { margin: 0; color: var(--txt2); }

.formula-box {
  background: rgba(6, 182, 212, 0.08); border: 1px solid var(--line);
  border-radius: 8px; padding: 1.2rem; margin: 1.4rem 0; text-align: center;
}
.formula-box code { font-size: 1.05rem; color: var(--txt); font-weight: 600; }

.data-table { width: 100%; border-collapse: collapse; margin: 1.4rem 0; font-size: 0.92rem; }
.data-table th, .data-table td {
  padding: 0.65rem 0.8rem; text-align: left;
  border-bottom: 1px solid var(--line); color: var(--txt2);
}
.data-table th { background: rgba(6, 182, 212, 0.12); color: var(--cyan); }

.inline-cta {
  background: linear-gradient(135deg, var(--navy2), rgba(6, 182, 212, 0.5));
  border-radius: 12px; padding: 1.8rem; margin: 2.2rem 0; text-align: center;
}
.inline-cta h3 { margin-bottom: 0.6rem; }
.inline-cta p { color: rgba(255, 255, 255, 0.85); margin-bottom: 1.2rem; }
.inline-cta .btn-cta { display: inline-block; font-size: 1.05rem; padding: 0.7rem 1.6rem; }

.faq { border-bottom: 1px solid var(--line); padding: 0.9rem 0; }
.faq summary { cursor: pointer; font-weight: 600; color: var(--txt); }
.faq p { margin-top: 0.6rem; }

.related { margin-top: 2.6rem; padding-top: 1.6rem; border-top: 1px solid var(--line); }
.related a { color: var(--cyan); }

.site-footer { margin-top: 3.5rem; border-top: 1px solid var(--line); background: rgba(15, 23, 42, 0.85); }
.footer-grid {
  max-width: 1100px; margin: 0 auto; padding: 2rem 1.25rem;
  display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 1.6rem;
}
.footer-grid h4 { color: var(--amber); font-size: 0.95rem; margin-bottom: 0.7rem; }
.footer-grid p, .footer-grid li { color: var(--txt2); font-size: 0.9rem; }
.footer-grid ul { list-style: none; }
.footer-grid li { margin-bottom: 0.35rem; }
.footer-grid a { color: var(--txt2); text-decoration: none; }
.footer-grid a:hover { color: var(--cyan); }
.footer-bottom { text-align: center; color: var(--txt2); font-size: 0.85rem; padding: 1.1rem; border-top: 1px solid var(--line); }

@media (max-width: 700px) {
  .hero h1, .article-body h1 { font-size: 1.6rem; }
  .nav-inner { gap: 0.9rem; }

     .brand { display: flex; align-items: center; gap: 0.55rem; }
   .brand img { width: 34px; height: 34px; background: #FFFFFF; border-radius: 6px; padding: 3px; }
}