:root{
  --header-bg: #ffffff;
  --accent: #0d6efd;
  --muted: #151515;
  --shadow-sm: 0 2px 6px rgba(0,0,0,0.06);
  --container: 1100px;
}

/* ===============================
   HEADER BASE
================================ */
.header-container {
  top: 0;
  left: 0;
  width: 100%;
  z-index: 9999;
  background: var(--header-bg);
  box-shadow: var(--shadow-sm);
  border-bottom: 1px solid rgba(0,0,0,0.04);
}

.header-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 10px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  box-sizing: border-box;
}

.header-left,
.header-center,
.header-right {
  display:flex;
  align-items:center;
  gap:12px;
}

/* images */
.header-container img {
  display:block;
  max-height:100px;
  object-fit:contain;
}
.header-logo,
.header-side-image {
  width: 140px;
  max-width:30vw;
}
.header-center-image {
  width: 160px;
  max-width:40vw;
}

/* ===============================
   NAVIGATION (DESKTOP)
================================ */
.header-nav {
  display:flex;
  align-items:center;
  gap: 25px;
}

.mobile-menu-icon {
  display:none;
  background:none;
  border:0;
  font-size:24px;
  cursor:pointer;
  padding:6px;
}

.nav-menu {
  list-style:none;
  display:flex;
  gap:1.5rem;
  margin:0;
  padding:0;
  align-items:center;
}
.nav-menu li {
  position:relative;
}

.nav-menu a {
  text-decoration:none;
  color:var(--muted);
  font-size:1rem;
  font-weight:600;
  padding:8px 4px;
  display:inline-block;
}
.nav-menu a:hover,
.nav-menu a:focus {
  color:var(--accent);
}

/* ===============================
   DROPDOWN (DESKTOP DEFAULT)
================================ */
.dropdown {
  display:none;
  position:absolute;
  top:calc(100% + 8px);
  left:0;
  min-width:180px;
  background:#fff;
  border-radius:8px;
  box-shadow: 0 6px 18px rgba(0,0,0,0.08);
  padding:8px 0;
  z-index:120;
  list-style:none;
}

.dropdown li a {
  display:block;
  padding:10px 14px;
  color:#222;
  font-size:0.95rem;
}
.dropdown li a:hover,
.dropdown li a:focus {
  background:var(--accent);
  color:#fff;
}

/* hover only for pointer devices */
@media (hover: hover) and (pointer: fine) {
  .nav-menu li:hover > .dropdown {
    display:block;
  }
}

/* JS toggle safety */
.nav-menu li.open > .dropdown {
  display:block;
}

/* ===============================
   BUTTONS
================================ */
.nav-buttons {
  display:flex;
  gap:10px;
  align-items:center;
}

.nav-buttons .btn-signin,
.nav-buttons .btn-register {
  padding:8px 14px;
  border-radius:8px;
  border:0;
  cursor:pointer;
  font-weight:700;
  font-size:0.9rem;
}

.btn-signin { background:#004d61; color:#fff; }
.btn-register { background:#555; color:#fff; }

/* ===============================
   SIDEBAR (BASE)
================================ */
.sidebar {
  position: fixed;
  right: 0;
  top: 0;
  height: 100%;
  width: 0;
  overflow-x: hidden;
  background:#fff;
  transition: width .32s ease;
  padding-top: 72px;
  box-shadow: -8px 0 30px rgba(0,0,0,0.06);
  z-index:10050;
}

.sidebar.open {
  width:320px;
  max-width:90%;
}

.sidebar .closebtn {
  position:absolute;
  top:12px;
  right:12px;
  font-size:28px;
  background:none;
  border:0;
  cursor:pointer;
}

.sidebar-links {
  list-style:none;
  padding:0 16px;
  margin:0 0 18px 0;
}

.sidebar-links li a {
  display:block;
  padding:12px 6px;
  color:#151515;
  text-decoration:none;
  font-size:1rem;
}

.sidebar .nav-buttons {
  padding: 0 16px;
  display:flex;
  flex-direction:column;
  gap:10px;
}

/* accessibility */
a:focus,
button:focus {
  outline: 3px solid rgba(13,110,253,0.14);
  outline-offset:3px;
}

/* ===============================
   RESPONSIVE
================================ */
@media (max-width: 1024px) {
  .header-center-image { max-width:260px; }
  .header-logo,
  .header-side-image { width:140px; }
}

@media (max-width: 768px) {

  .header-inner {
    padding: 8px 12px;
    gap: 8px;
  }

  .header-logo,
  .header-side-image {
    display: none;
  }

  .header-center-image {
    display: block;
    max-width: 180px;
  }

  .nav-menu,
  .nav-buttons {
    display: none;
  }

  .mobile-menu-icon {
    display: block;
  }

  /* ===============================
     MOBILE SIDEBAR (PANEL)
  ================================ */
  .sidebar {
    position: fixed;
    top: 0;
    right: 0;
    height: 100%;
    width: 320px;
    max-width: 90%;
    background: #fff;
    padding-top: 72px;
    box-shadow: -8px 0 30px rgba(0,0,0,0.06);
    overflow-y: auto;
    z-index: 10050;

    /* CLOSED STATE */
    transform: translateX(100%);
    transition: transform 0.32s ease;
  }

  /* OPEN STATE */
  .sidebar.open {
    transform: translateX(0);
  }

  /* ===============================
     MOBILE MENU
  ================================ */
  .mobile-menu {
    list-style: none;
    
    margin: 0;
  }

  .menu-head {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  .mobile-menu a {
    display: block;
    padding: 14px 16px;
    color: #222;
    text-decoration: none;
  }

  .dropdown-toggle {
    background: none;
    border: none;
    font-size: 22px;
    cursor: pointer;
  }

  /* ===============================
     MOBILE DROPDOWN (ACCORDION)
  ================================ */
  .sidebar .dropdown {
    position: static;
    display: block;
    max-height: 0;
    overflow: hidden;
    background: #f9f9f9;
    box-shadow: none;
    margin-left: 8px;
    border-radius: 6px;
    padding: 0;
    transition: max-height 0.3s ease;
  }

  .sidebar .has-dropdown.open > .dropdown {
    max-height: 500px;
  }
}

/* small screens */
@media (max-width: 420px) {
  .header-center-image { max-width:150px; }

  .nav-buttons .btn-signin,
  .nav-buttons .btn-register {
    font-size:0.95rem;
    padding:8px 10px;
  }
}