/* Sets shared colors so the page stays consistent and easy to update. */
:root {
  color: #1f2937;
  background: #f3f4f6;
  font-family: Arial, sans-serif;
}

/* Removes the default page margin so each layout section aligns cleanly. */
body {
  margin: 0;
}

/* Keeps the header visible while scrolling, so navigation is always available. */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1;
  padding: 1rem 2rem;
  background: #1d4ed8;
  color: white;
}

/* Makes the navigation links sit in a flexible horizontal row with even spacing. */
.site-nav {
  display: flex;
  gap: 1rem;
}

/* Makes each navigation link clear and easy to read against the header. */
.site-nav a {
  color: inherit;
  font-weight: bold;
  text-decoration: none;
}

/* Centers the page content and gives it comfortable breathing room. */
.page-main {
  max-width: 900px;
  margin: 0 auto;
  padding: 3rem 2rem;
}

/* Uses flexbox to place the two cards side by side and wrap them on narrow screens. */
.cards {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
}

/* Lets each card grow evenly, keeping the two-card layout balanced. */
.card {
  flex: 1 1 280px;
  padding: 1.5rem;
  border-radius: 0.75rem;
  background: white;
  box-shadow: 0 4px 12px rgb(0 0 0 / 10%);
}

/* Creates a two-column grid so small items line up in both rows and columns. */
.grid-example {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.75rem;
}

/* Styles each grid item so the grid structure is easy to see. */
.grid-item {
  padding: 0.75rem;
  border-radius: 0.5rem;
  background: #dbeafe;
  text-align: center;
}

/* Hides optional content completely so it takes up no page space. */
.hidden-note {
  display: none;
}

/* Gives content sections enough vertical rhythm to actually force scroll,
   so the sticky header below has real distance to demonstrate sticking. */
.content-block {
  margin-top: 2.5rem;
}

.content-block h2 {
  margin-bottom: 0.5rem;
}

.content-block p {
  line-height: 1.6;
  margin: 0 0 1rem;
}

/* Gives the footer a distinct ending area that matches the header. */
.site-footer {
  padding: 1.5rem 2rem;
  background: #1f2937;
  color: white;
  text-align: center;
}