#main-content {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.3s ease, transform 0.4s ease;
}
#main-content.fade-out {
  opacity: 0;
  transform: translateY(20px);
}
#main-content.fade-in {
  opacity: 1;
  transform: translateY(0);
}


/* Reset and base styles */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  /* Keep header height consistent for layout offsets */
  --nav-height: 64px;
}

html, body {
  /* Do not constrain overflow on ancestors of sticky header */
  overflow-x: visible !important;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background-color: #ffffff;
  color: #222222;
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Links */
a {
  color: #000000;
  text-decoration: none;
  transition: color 0.3s ease;
}

a:hover,
a:focus {
  color: #555555;
  outline: none;
}

/* Navigation (sticky header) */
nav {
  position: sticky;       /* ensure sticky */
  top: 0;                 /* threshold required */
  z-index: 11100;          /* ensure above menus/content */
  background-color: #111111;
  padding: 1rem 0;
  min-height: var(--nav-height);
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.15);
}

/* Mobile hamburger toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.8rem;
  color: #ffffff;
  cursor: pointer;
  padding: 0.5rem;
  position: absolute;
  top: 50%;
  right: 1.5rem;
  transform: translateY(-50%);
  transition: color 0.3s ease;
  z-index: 1200; /* above nav-menu */
}

.nav-toggle:hover {
  color: #cccccc;
}

/* Navigation menu */
.nav-menu {
  display: flex;
  justify-content: center;
  list-style: none;
  flex-wrap: wrap;
  transition: all 0.3s ease;
}

.nav-menu li {
  margin: 0 1.25rem;
}

.nav-menu li a {
  color: #ffffff;
  font-weight: 600;
  font-size: 1rem;
  padding: 0.4rem 0.6rem;
  border-radius: 4px;
  transition: background-color 0.3s ease;
  display: block;
}

.nav-menu li a:hover,
.nav-menu li a:focus,
.nav-menu li a.active {
  background-color: #333333;
  color: #ffffff;
  outline: none;
}

.nav-menu li a.active {
  background-color: #555555;
}

/* Footer */
footer {
  background-color: #111111;
  color: #dddddd;
  text-align: center;
  padding: 1.1rem;
  font-size: 0.95rem;
  margin-top: auto;
}

/* Main content area */
#main-content {
  flex: 1;
  padding: 2rem;
  transition: opacity 0.3s ease;
  min-height: 400px;
  animation: fadeIn 0.3s ease;
}

.loading-state { opacity: 0.5; pointer-events: none; }
.fade-out { opacity: 0; }
.fade-in { opacity: 1; }

/* Focus accessibility improvements */
.nav-toggle:focus,
.nav-menu a:focus {
  outline: 2px solid #ffffff;
  outline-offset: 2px;
}

/* Prevent body scroll when mobile menu is open (without breaking sticky) */
body.menu-open {
  /* Use clip so we don't create a new scrolling container */
  overflow: clip;
}

/* Fallback if overflow: clip is unsupported */
@supports not (overflow: clip) {
  body.menu-open {
    position: fixed; /* lock scroll */
    inset: 0;
    width: 100%;
  }

  /* Ensure header remains pinned while body is fixed */
  body.menu-open nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
  }
}

/* Responsive design for mobile */
@media (max-width: 768px) {
  .nav-toggle {
    display: block;
  }

  /* Hide menu by default on mobile, make it an overlay panel */
  .nav-menu {
    position: fixed;
    left: -100%;
    top: var(--nav-height); /* sit below header */
    flex-direction: column;
    background-color: #111111;
    width: 100%;
    text-align: center;
    transition: left 0.3s ease;
    box-shadow: 0 10px 27px rgba(0, 0, 0, 0.05);
    z-index: 1000; /* below nav */
    padding: 2rem 0;
  }

  /* Show menu when active */
  .nav-menu.show-menu {
    left: 0;
  }

  /* Mobile menu items */
  .nav-menu li {
    margin: 0.5rem 0;
  }

  .nav-menu li a {
    padding: 1rem 2rem;
    font-size: 1.1rem;
    border-radius: 0;
    width: 100%;
    transition: background-color 0.3s ease, padding-left 0.3s ease;
  }

  .nav-menu li a:hover,
  .nav-menu li a:focus {
    background-color: #333333;
    padding-left: 3rem;
  }

  .nav-menu li a.active {
    background-color: #555555;
    border-left: 4px solid #ffffff;
  }

  /* Adjust main content padding for mobile */
  #main-content {
    padding: 1rem;
  }
}

/* Additional mobile optimizations */
@media (max-width: 480px) {
  nav {
    padding: 0.8rem 0;
  }

  .nav-toggle {
    right: 1rem;
    font-size: 1.6rem;
  }

  .nav-menu {
    top: var(--nav-height);
    padding: 1.5rem 0;
  }

  .nav-menu li a {
    font-size: 1rem;
    padding: 0.8rem 1.5rem;
  }
}

/* Smooth loading animation */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}