:root{
  --brand:#111827;
  --accent:#38bdf8;
  --accent-2:#06b6d4;
}
html{scroll-behavior:smooth}
body{font-family:system-ui,-apple-system,Segoe UI,Roboto,Ubuntu,'Helvetica Neue',Arial,'Noto Sans',sans-serif; color:#111; background:#fafafa}
.hero-gradient{background:linear-gradient(180deg,#0b1220 0%,#14213d 60%,#111827 100%)}
.hero-gradient .lead, .hero-gradient h1, .hero-gradient p{color:#fff}
.navbar-brand img{height:32px}
.table-responsive{overflow-x:auto}
.btn-go{background:linear-gradient(90deg,var(--accent),var(--accent-2)); border:0; color:#fff}
.btn-go:hover{filter:brightness(1.05); color:#fff}
.badge-soft{background:rgba(56,189,248,.12); color:#0369a1}
footer{background:#0b1220; color:#cbd5e1}
.card{border-radius:14px}
.toc a{ text-decoration:none }
figure img{border-radius:12px}
small.hint{color:#6b7280}
/* Mobile tweaks */
@media (max-width: 575.98px){
  .display-5{font-size:2rem}
}