:root {
  --sidebar-width: 500px;
  --topbar-height: 56px;

  --bg: #f4f6f8;
  --sidebar-bg: #0f2942;
  --sidebar-bg-2: #143552;
  --sidebar-text: #c7d4e1;
  --sidebar-text-dim: #8aa0b6;
  --sidebar-active-bg: #1d6fb8;
  --sidebar-active-text: #ffffff;
  --sidebar-hover-bg: #1a4060;
  --accent: #1d6fb8;
  --border: #d8dee5;
  --shadow: 0 2px 12px rgba(15, 41, 66, 0.12);

  --transition: 0.22s ease;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: #1f2d3a;
}

/* ---------- Top bar (mobile/tablet) ---------- */
.topbar {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--topbar-height);
  background: var(--sidebar-bg);
  color: #fff;
  align-items: center;
  gap: 14px;
  padding: 0 16px;
  z-index: 40;
  box-shadow: var(--shadow);
}

.topbar-title {
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 0.2px;
}

.hamburger {
  width: 38px;
  height: 38px;
  border: none;
  background: transparent;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
  border-radius: 6px;
}
.hamburger span {
  display: block;
  height: 2px;
  width: 100%;
  background: #fff;
  border-radius: 2px;
  transition: var(--transition);
}
.hamburger:hover { background: rgba(255, 255, 255, 0.12); }

/* ---------- Sidebar ---------- */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--sidebar-width);
  background: linear-gradient(180deg, var(--sidebar-bg) 0%, var(--sidebar-bg-2) 100%);
  color: var(--sidebar-text);
  display: flex;
  flex-direction: column;
  z-index: 50;
  overflow-y: auto;
}

.sidebar-close {
  display: none;
  position: absolute;
  top: 14px;
  right: 14px;
  width: 36px;
  height: 36px;
  border: none;
  background: rgba(255, 255, 255, 0.08);
  color: #fff;
  font-size: 26px;
  line-height: 1;
  border-radius: 6px;
  cursor: pointer;
  z-index: 2;
  transition: var(--transition);
}
.sidebar-close:hover { background: rgba(255, 255, 255, 0.18); }

.brand {
  padding: 22px 22px 18px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}
.brand-title {
  font-size: 18px;
  font-weight: 700;
  color: #fff;
  letter-spacing: 0.2px;
}
.brand-subtitle {
  font-size: 12px;
  color: var(--sidebar-text-dim);
  margin-top: 3px;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.nav { padding: 12px 0; flex: 1; }

.module { border-bottom: 1px solid rgba(255, 255, 255, 0.05); }

.module-header {
  width: 100%;
  background: transparent;
  border: none;
  color: var(--sidebar-text);
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  padding: 14px 22px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  transition: var(--transition);
}
.module-header:hover { background: var(--sidebar-hover-bg); color: #fff; }

.chevron {
  width: 8px;
  height: 8px;
  border-right: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
  transform: rotate(45deg);
  transition: transform var(--transition);
  opacity: 0.8;
}
.module-header[aria-expanded="false"] .chevron { transform: rotate(-45deg); }

.module-items {
  list-style: none;
  margin: 0;
  padding: 0 0 6px;
  overflow: hidden;
}
.module-header[aria-expanded="false"] + .module-items { display: none; }

/* Sub-module: a collapsible group nested inside .module-items */
.submodule { list-style: none; }
.submodule-header {
  width: 100%;
  background: transparent;
  border: none;
  color: var(--sidebar-text);
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  padding: 9px 22px 9px 36px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  transition: var(--transition);
}
.submodule-header:hover { background: var(--sidebar-hover-bg); color: #fff; }
.submodule-header[aria-expanded="false"] .chevron { transform: rotate(-45deg); }

.submodule-items {
  list-style: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
}
.submodule-header[aria-expanded="false"] + .submodule-items { display: none; }

/* Sub-sub-module: a collapsible group nested inside .submodule-items */
.subsubmodule { list-style: none; }
.subsubmodule-header {
  width: 100%;
  background: transparent;
  border: none;
  color: var(--sidebar-text-dim);
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 8px 22px 8px 50px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  transition: var(--transition);
}
.subsubmodule-header:hover { background: var(--sidebar-hover-bg); color: #fff; }
.subsubmodule-header[aria-expanded="false"] .chevron { transform: rotate(-45deg); }

.subsubmodule-items {
  list-style: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
}
.subsubmodule-header[aria-expanded="false"] + .subsubmodule-items { display: none; }

.nav-link {
  display: block;
  color: var(--sidebar-text);
  text-decoration: none;
  font-size: 14px;
  padding: 9px 22px 9px 29px;
  border-left: 10px solid transparent;
  transition: var(--transition);
}
/* Indent links one extra level when they live inside a sub-module */
.submodule-items .nav-link { padding-left: 43px; }
/* Indent links one more level inside a sub-sub-module */
.subsubmodule-items .nav-link { padding-left: 57px; }
.nav-link:hover { background: var(--sidebar-hover-bg); color: #fff; }
.nav-link.active {
  background: var(--sidebar-active-bg);
  color: var(--sidebar-active-text);
  border-left-color: #8fd0ff;
  font-weight: 600;
}
/* horizontal separator between nav links — left edge aligns with the link
   text (border 10px + sub-sub-module padding 57px), runs to the right edge */
.nav-divider {
  height: 1px;
  background: rgba(255, 255, 255, 0.14);
  margin: 6px 0 6px 67px;
  list-style: none;
}

.sidebar-footer {
  padding: 14px 22px;
  font-size: 11px;
  color: var(--sidebar-text-dim);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

/* ---------- Content ---------- */
.content {
  margin-left: var(--sidebar-width);
  height: 100vh;
}
.content-frame {
  border: none;
  width: 100%;
  height: 100%;
  display: block;
  background: #fff;
}

.backdrop {
  position: fixed;
  inset: 0;
  background: rgba(15, 41, 66, 0.5);
  z-index: 45;
  opacity: 0;
  transition: opacity var(--transition);
}
.backdrop.show { opacity: 1; }

/* ---------- Responsive: drawer on mobile/tablet ---------- */
@media (max-width: 1024px) {
  .topbar { display: flex; }
  .sidebar-close { display: block; }

  .sidebar {
    top: 0;
    transform: translateX(-100%);
    transition: transform var(--transition);
    box-shadow: var(--shadow);
  }
  .sidebar.open { transform: translateX(0); }

  .content {
    margin-left: 0;
    padding-top: var(--topbar-height);
    height: 100vh;
  }
}

/* Phones: the drawer takes the full screen width */
@media (max-width: 640px) {
  .sidebar { width: 100%; }
}