/* Header & Navigation (mobile-first, CSS-only) */

/* ------ CSS Variables ------ */
:root {
  --header-bg-color: #223046;
  --header-accent-color: #2bb3a3;
  --header-text-color: #fff;
  --header-height-desktop: 90px;
  --header-height-mobile: 70px;
  --header-z-index: 1000;
  --dropdown-bg-color: #fff;
  --dropdown-text-color: #223046;
  --transition-speed: 0.3s;
}

/* ------ Header Container ------ */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  z-index: var(--header-z-index);
  width: 100vw;
  min-height: var(--header-height-desktop);
  background: var(--header-bg-color);
  color: var(--header-text-color);
  transition: background var(--transition-speed) ease;
}

/* ------ Header Layout ------ */
.header-content {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  width: 100%;
  min-height: var(--header-height-desktop);
  padding: 0 2rem;
  box-sizing: border-box;
}

/* ------ Logo Section ------ */
.header-left {
  grid-column: 1;
  display: flex;
  align-items: center;
  justify-content: flex-start;
}

.header-title-link {
  display: flex;
  align-items: center;
  text-decoration: none;
  color: inherit;
  transition: color calc(var(--transition-speed) * 0.67) ease;
}

.header-title-link:hover,
.header-title-link:focus {
  color: var(--header-accent-color);
}

.header-logo {
  height: 4rem;
  width: auto;
  filter: brightness(1.1);
  transition: transform calc(var(--transition-speed) * 0.67) ease;
}

.header-logo:hover {
  transform: scale(1.05);
}

/* ------ Main Navigation ------ */
.site-nav {
  grid-column: 2;
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.5rem;
}

/* ------ Navigation Visibility Control ------ */
.mobile-dropdown-label {
  display: none;
}

.desktop-dropdown-link {
  display: inline-block;
}

/* ------ Base Navigation Styles ------ */
.site-nav a,
.site-nav .dropbtn {
  display: inline-block;
  margin: 0 0.625rem;
  padding: 0.5rem 1.125rem;
  font-size: 1.08rem;
  font-weight: 500;
  text-decoration: none;
  color: var(--header-text-color);
  background: none;
  border: none;
  border-radius: 0.375rem;
  outline: none;
  cursor: pointer;
  transition: background calc(var(--transition-speed) * 0.67) ease, 
              color calc(var(--transition-speed) * 0.67) ease,
              transform calc(var(--transition-speed) * 0.67) ease;
  will-change: transform;
}

.site-nav a:hover,
.site-nav a:focus,
.site-nav .dropbtn:hover,
.site-nav .dropbtn:focus {
  background: var(--header-accent-color);
  color: var(--header-text-color);
  text-decoration: none;
}

/* ------ Desktop Dropdown Menus ------ */
.dropdown {
  position: relative;
  display: inline-block;
}

.dropdown::after {
  content: "";
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  height: 0.625rem;
  z-index: var(--header-z-index);
}

.dropdown-content {
  position: absolute;
  top: 100%;
  left: 0;
  z-index: calc(var(--header-z-index) + 1);
  display: block; /* keep in flow to avoid reflow on hover */
  min-width: 13.125rem;
  padding: 0;
  margin-top: 0;
  background-color: var(--dropdown-bg-color);
  border-radius: 0.625rem;
  box-shadow: 0 0.5rem 1.5rem rgba(0, 0, 0, 0.13);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.15s ease, visibility 0.15s ease;
}

.dropdown-content a {
  display: block;
  padding: 0.75rem 1.375rem;
  font-weight: 500;
  text-align: left;
  text-decoration: none;
  color: var(--dropdown-text-color);
  background: none;
  border-radius: 0;
  transition: background 0.18s ease, color 0.18s ease;
}

.dropdown-content a:hover {
  background-color: #f7f9fa;
  color: var(--header-accent-color);
}

.dropdown:hover .dropdown-content,
.dropdown:focus-within .dropdown-content {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

/* Desktop layout (>= 900px) */
@media (min-width: 56.25em) {
  .header-content {
    grid-template-columns: auto 1fr;
    padding: 0;
  }
  
  .header-left {
    justify-self: start;
    padding-left: 2rem;
  }
  
  .site-nav {
    justify-content: center;
    justify-self: center;
    padding-right: 2rem;
  }
  
  .dropdown-content {
    min-width: 13.75rem;
  }
  
  .mobile-dropdown-label {
    display: none !important;
  }
  
  .desktop-dropdown-link {
    display: inline-block !important;
  }
}

/* Desktop: create a small visual gap when a dropdown is opened */
@media (min-width: 56.25em) {
  /* nudge the parent button up slightly when hovered/focused to reveal a gap */
  .dropdown:hover > .dropbtn,
  .dropdown:focus-within > .dropbtn {
    transform: translateY(-8px);
  }

  /* move the dropdown a little further down to keep distance from the parent */
  .dropdown:hover .dropdown-content,
  .dropdown:focus-within .dropdown-content {
    top: calc(100% + 8px);
  }
}

/* ------ Touch Device Optimizations ------ */
@media (max-width: 56.25em) {
  /* Disable desktop-like hover opening on touch/mobile to prevent layout shifts */
  .dropdown:hover .dropdown-content,
  .dropdown:focus-within .dropdown-content {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
  }

  .dropdown:active .dropdown-content,
  .dropdown:focus .dropdown-content {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
  }
  
  .dropbtn {
    -webkit-tap-highlight-color: transparent;
  }
}

/* Mobile navigation - CSS-only */
.mobile-menu-toggle,
.dropdown-toggle {
  position: absolute;
  left: -9999px;
  opacity: 0;
}

/* ------ Hamburger Menu Button ------ */
.mobile-menu-button {
  display: none;
  flex-direction: column;
  padding: 0.5rem;
  border-radius: 0.25rem;
  cursor: pointer;
  transition: background calc(var(--transition-speed) * 0.67) ease;
}

.mobile-menu-button:hover {
  background: rgba(255, 255, 255, 0.1);
}

/* ------ Hamburger Icon ------ */
.hamburger-line {
  width: 1.5rem;
  height: 0.125rem;
  background: var(--header-text-color);
  border-radius: 0.0625rem;
  margin: 0.1875rem 0;
  transition: all var(--transition-speed) ease;
}

/* ------ Mobile Layout (900px and below) ------ */
@media (max-width: 56.25em) {
  .header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.9375rem 1.25rem;
    min-height: var(--header-height-mobile);
  }
  
  .header-left {
    flex: 0 0 auto;
  }
  
  .header-logo {
    height: 3.125rem;
  }
  
  .header-title-link {
    padding: 0.5rem;
    border-radius: 0.5rem;
    transition: background calc(var(--transition-speed) * 0.67) ease;
  }
  
  .header-title-link:hover {
    background: rgba(255, 255, 255, 0.1);
  }
  
  .mobile-menu-button {
    display: flex;
  }
  
  .site-nav {
    position: fixed;
    top: var(--header-height-mobile);
    left: 0;
    z-index: calc(var(--header-z-index) - 1);
    width: 100%;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 1.25rem 0;
    background: var(--header-bg-color);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 0.25rem 0.75rem rgba(0, 0, 0, 0.15);
    transform: translateY(-100%);
    visibility: hidden;
    opacity: 0;
    transition: all var(--transition-speed) ease;
  }
  
  .mobile-menu-toggle:checked ~ .site-nav {
    transform: translateY(0);
    visibility: visible;
    opacity: 1;
  }
  
  /* ------ Hamburger Animation ------ */
  .mobile-menu-toggle:checked + .mobile-menu-button .hamburger-line:nth-child(1) {
    transform: rotate(45deg) translate(0.3125rem, 0.3125rem);
  }
  
  .mobile-menu-toggle:checked + .mobile-menu-button .hamburger-line:nth-child(2) {
    opacity: 0;
  }
  
  .mobile-menu-toggle:checked + .mobile-menu-button .hamburger-line:nth-child(3) {
    transform: rotate(-45deg) translate(0.4375rem, -0.375rem);
  }
  
  .site-nav > a,
  .site-nav > .dropdown {
    width: 100%;
    margin: 0;
  }
  
  .site-nav > a,
  .site-nav > .dropdown > .mobile-dropdown-label {
    display: block;
    width: 100%;
    padding: 1rem 1.25rem;
    box-sizing: border-box;
    font-size: 1.1rem;
    text-align: left;
    border-radius: 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    cursor: pointer;
    transition: background calc(var(--transition-speed) * 0.67) ease;
  }
  
  .site-nav > a:hover,
  .site-nav > .dropdown > .mobile-dropdown-label:hover {
    background: rgba(43, 179, 163, 0.2);
  }
  
  .site-nav > a:last-child {
    border-bottom: none;
  }
  
  .dropdown {
    width: 100%;
    position: relative;
    flex-shrink: 0;
  }
  
  /* ------ Mobile Navigation Visibility ------ */
  .desktop-dropdown-link {
    display: none !important;
  }
  
  .mobile-dropdown-label {
    display: block !important;
    cursor: pointer;
    width: 100%;
  }
  
  .dropdown-content {
    position: static; /* expand inline */
    transform: none;
    box-shadow: none;
    border-radius: 0;
    margin: 0;
    padding: 0;
    opacity: 0;
    display: block;
    background: var(--header-bg-color);
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-speed) ease-out,
                opacity var(--transition-speed) ease-out,
                visibility var(--transition-speed) ease-out;
    visibility: hidden;
    pointer-events: none;
    border-top: 1px solid rgba(255,255,255,0.06);
  }
  
  /* Dropdown open state (both can be open) */
  #dropdown-conference-toggle:checked ~ .site-nav .dropdown:nth-of-type(1) .dropdown-content,
  #dropdown-attending-toggle:checked ~ .site-nav .dropdown:nth-of-type(2) .dropdown-content {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    max-height: 20rem;
  }

  /* Visual active state for opened parent rows */
  #dropdown-conference-toggle:checked ~ .site-nav .dropdown:nth-of-type(1) > .mobile-dropdown-label,
  #dropdown-attending-toggle:checked ~ .site-nav .dropdown:nth-of-type(2) > .mobile-dropdown-label {
    background: rgba(43, 179, 163, 0.2);
  }
  
  /* Mobile submenu links */
  .dropdown-content a {
    padding: 0.9rem 1.25rem 0.9rem 2.5rem;
    font-size: 1rem;
    color: #e8eef7;
    background: rgba(255,255,255,0.02);
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    transition: background calc(var(--transition-speed) * 0.67) ease, color calc(var(--transition-speed) * 0.67) ease;
  }
  
  .dropdown-content a:hover {
    background: rgba(43, 179, 163, 0.16);
    color: var(--header-accent-color);
  }
  
  .dropdown-content a:last-child {
    border-bottom: none;
  }
}

/* ------ Small Mobile Devices (600px and below) ------ */
@media (max-width: 37.5em) {
  .header-content {
    padding: 0.75rem 0.9375rem;
    min-height: 4.0625rem;
  }
  
  .header-logo {
    height: 2.875rem;
  }
  
  .header-title-link {
    padding: 0.375rem;
  }
  
  .site-nav {
    top: 4.0625rem;
    padding: 0.9375rem 0;
  }
  
  .site-nav > a,
  .site-nav > .dropdown > .mobile-dropdown-label {
    padding: 0.875rem 0.9375rem;
    font-size: 1rem;
  }
  
  .dropdown-content a {
    padding: 0.75rem 1.875rem;
    font-size: 0.95rem;
  }
}

/* ------ Extra Small Mobile Devices (400px and below) ------ */
@media (max-width: 25em) {
  .header-content {
    padding: 0.625rem 0.75rem;
    min-height: 3.75rem;
  }
  
  .header-logo {
    height: 2.625rem;
  }
  
  .header-title-link {
    padding: 0.25rem;
  }
  
  .site-nav {
    top: 3.75rem;
    padding: 0.75rem 0;
  }
  
  .site-nav > a,
  .site-nav > .dropdown > .mobile-dropdown-label {
    padding: 0.75rem;
    font-size: 0.95rem;
  }
  
  .dropdown-content a {
    padding: 0.625rem 1.5rem;
    font-size: 0.9rem;
  }
}

/* End header styles */