* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  background: #0f172a;
  color: #e5e7eb;
}

/* Add a black background color to the top navigation */
.topnav {
  background: linear-gradient(90deg, #3b82f6, #22c55e);
  overflow: hidden;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.4);
  position: sticky;
  top: 0;
  z-index: 1000;
}

/* Style the links inside the navigation bar */
.topnav a {
  float: left;
  display: block;
  color: #fefce8;
  text-align: center;
  padding: 16px 20px;
  text-decoration: none;
  font-size: 22px;
  letter-spacing: 0.03cm;
  text-transform: uppercase;
  font-weight: 600;
  transition: background-color 0.25s ease, color 0.25s ease, transform 0.15s ease;
}

/* Change the color of links on hover */
.topnav a:hover {
  background-color: rgba(15,23,42,0.18);
  color: #facc15;
  transform: translateY(-1px);
}

/* Add an active class to highlight the current page */
.topnav a.active {
  background-color: rgba(15,23,42,0.35);
  color: #fef9c3;
  box-shadow: inset 0 -3px 0 #f97316;
}

/* Hide the icon that should open and close the topnav on small screens */
.topnav .icon {
  display: none;
  font-size: 24px;
}

/* Style for page content */
.content {
  padding: 24px 18px;
  max-width: 1100px;
  margin: 24px auto;
  background: radial-gradient(circle at top left, rgba(56, 189, 248, 0.08), transparent),
              radial-gradient(circle at bottom right, rgba(34, 197, 94, 0.10), transparent),
              #020617;
  border-radius: 18px;
  border: 1px solid rgba(148, 163, 184, 0.25);
  box-shadow: 0 18px 40px rgba (0, 0, 0, 0.6);
  font-size: 20px;
  line-height: 1.7;
}

/* When the screen is less than 800 pixels wide */
@media screen and (max-width: 800px) {
  /* Hide all links, except for the selected tab */
  .topnav a:not(.active) {
    display: none;
  }

  /* Show the icon that should open and close the topnav */
  .topnav a.icon {
    float: right;
    display: block;
  }
}

/* When the screen is less than 800 pixels wide, if the user clicks on the icon */
/* the "responsive" class attribute will be added to the topnav by the JavaScript code */
/* This media query sets the style for the unfolded topnav */
/* It makes the topnav look good on small screens (display the links vertically instead of horizontally)  */
@media screen and (max-width: 800px) {
  .topnav.responsive {
    position: relative;
  }

  .topnav.responsive a.icon {
    position: absolute;
    right: 0;
    top: 0;
  }

  .topnav.responsive a {
    float: none;
    display: block;
    text-align: left;
    border-top: 1px solid rgba(15, 23, 42, 0.35);
  }

  .content {
    margin: 16px;
    padding: 18px 14px;
    font-size: 18px;
  }
}