/* --- Global Typography & Background --- */
body {
  margin: 0;
  font-family: "Inter", "Segoe UI", sans-serif;
  background: linear-gradient(135deg, #e3f2fd 0%, #ede7f6 40%, #f3e5f5 100%);
  background-attachment: fixed;
  color: #222;
  transition: background 0.6s ease;
  min-height: 100vh;
}

/* Optional: add a slight overlay for a subtle frosted effect */
body::after {
  content: "";
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(
    circle at top left,
    rgba(63, 81, 181, 0.08),
    rgba(103, 58, 183, 0.08)
  );
  pointer-events: none;
  z-index: -1;
}

/* --- Header Banner (Branding) --- */
body::before {
  content: " Learn PostgreSQL";
  display: block;
  text-align: center;
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: 0.5px;
  padding: 12px;
  background: linear-gradient(90deg, #3f51b5, #5c6bc0, #7e57c2);
  color: #fff;
  box-shadow: 0 2px 6px rgba(63, 81, 181, 0.3);
  border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}

/* --- PDF Link Highlight --- */
a[href$=".pdf"] {
  color: #ff5722;
  font-weight: 600;
  text-decoration: underline dotted;
  transition: color 0.3s ease;
}

a[href$=".pdf"]:hover {
  color: #e64a19;
  text-decoration: underline solid;
}

/* --- Back-to-Top Button --- */
.back-to-top {
  position: fixed;
  right: 20px;
  bottom: 24px;
  width: 52px;
  height: 52px;
  border-radius: 50%;
  border: none;
  background: linear-gradient(145deg, #3f51b5, #5c6bc0);
  box-shadow: 0 6px 14px rgba(63, 81, 181, 0.3);
  color: #fff;
  font-size: 24px;
  cursor: pointer;
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 0.4s ease, transform 0.3s ease, box-shadow 0.3s ease, background 0.3s ease;
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
}

.back-to-top:hover,
.back-to-top:focus {
  background: linear-gradient(145deg, #303f9f, #512da8);
  box-shadow: 0 8px 18px rgba(63, 81, 181, 0.4);
  transform: translateY(-3px);
  outline: none;
}

.back-to-top:active {
  transform: translateY(1px);
}

/* --- Docsify Content Area --- */
#app {
  padding-top: 10px;
}

.markdown-section h1,
.markdown-section h2,
.markdown-section h3 {
  color: #3f51b5;
  font-weight: 600;
}

.markdown-section a {
  color: #3949ab;
  text-decoration: none;
  transition: color 0.3s ease;
}

.markdown-section a:hover {
  color: #1a237e;
  text-decoration: underline;
}

/* --- Reduced Motion Accessibility --- */
@media (prefers-reduced-motion: reduce) {
  .back-to-top {
    transition: none;
  }
}

/* --- Smooth Scroll --- */
html {
  scroll-behavior: smooth;
}

/* --- Vertical Border Before Each Heading --- */
.markdown-section h1,
.markdown-section h2,
.markdown-section h3 {
  border-left: 4px solid #7e57c2; /* purple vertical line */
  padding-left: 12px;             /* space between border and text */
  margin-left: 0;
  color: #3f51b5;                 /* main heading color */
  font-weight: 600;
  line-height: 1.4;
  margin-top: 1.5em;
}