:root {
  --navbar-height: 60px;
  --nav-bg: rgba(248, 250, 252, 0.95);
  --nav-border: rgba(226, 232, 240, 0.9);
  --nav-text: #333333;
  --nav-accent: #4a90e2;
  --nav-pill-bg: rgba(255, 255, 255, 0.8);
  --nav-radius: 999px;
  --nav-item-radius: 10px;
  --shadow-sm: 0 2px 6px rgba(0, 0, 0, 0.06);
  --sidebar-collapsed: 0px;
  --sidebar-expanded: 240px;
  --sidebar-current: var(--sidebar-collapsed);
}

body {
  padding-left: var(--sidebar-current);
  transition: padding-left 0.25s ease;
}

.top-navbar {
  position: fixed;
  inset-inline: 0;
  top: 0;
  height: var(--navbar-height);
  background-color: var(--nav-bg);
  backdrop-filter: blur(18px);
  border-bottom: 1px solid var(--nav-border);
  display: flex;
  align-items: center;
  justify-content: flex-start;
  padding-inline: 20px;
  z-index: 1000;
  box-shadow: var(--shadow-sm);
}

.navbar-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.subject-sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  width: var(--sidebar-expanded);
  background: #f8fafc;
  border-right: 1px solid var(--nav-border);
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 12px 8px;
  z-index: 900;
  transition: width 0.25s ease, box-shadow 0.25s ease;
  box-shadow: 2px 0 12px rgba(0, 0, 0, 0.06);

  transform: translateX(-100%);
  opacity: 0;
  pointer-events: none;

  transition: 
   transform 0.25s ease,
   opacity 0.25s ease,
   pointer-events 0.25s ease,
   width 0.25s ease,
   box-shadow 0.25s ease;
}

.subject-sidebar.open {
  transform: translateX(0);
  opacity: 1;
  pointer-events: auto;
}

.subject-toggle-nav {
  width: 40px;
  height: 40px;
  border-radius: 12px;
  border: 1px solid var(--nav-border);
  background: #ffffff;
  cursor: pointer;
  font-size: 18px;
  line-height: 1;
  display: grid;
  place-items: center;
  transition: all 0.2s ease;
}

.subject-toggle-nav:hover {
  color: var(--nav-accent);
  border-color: var(--nav-accent);
  box-shadow: 0 4px 10px rgba(74, 144, 226, 0.18);
}

.subject-drawer {
  width: 100%;
  height: calc(100vh - var(--navbar-height) - 12px);
  overflow-y: auto;
  border-radius: 12px;
  padding: 12px;
  background: #ffffff;
  border: 1px solid var(--nav-border);
  opacity: 0;
  pointer-events: none;
  transform: translateX(-8px);
  transition: opacity 0.2s ease, transform 0.2s ease;
  margin-top: calc(var(--navbar-height) - 8px);
}

.subject-sidebar.open .subject-drawer {
  opacity: 1;
  pointer-events: auto;
  transform: translateX(0);
}

.drawer-title {
  font-weight: 700;
  margin: 0;
}

.drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
  gap: 8px;
}

.subject-close {
  width: 28px;
  height: 28px;
  border-radius: 8px;
  border: 1px solid var(--nav-border);
  background: #ffffff;
  cursor: pointer;
  font-size: 16px;
  line-height: 1;
  display: grid;
  place-items: center;
  transition: all 0.2s ease;
}

.subject-close:hover {
  color: var(--nav-accent);
  border-color: var(--nav-accent);
  box-shadow: 0 4px 10px rgba(74, 144, 226, 0.18);
}
.subject-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.subject-list li {
  margin-bottom: 6px;
}

.subject-link {
  display: block;
  padding: 8px 10px;
  border-radius: 10px;
  color: var(--nav-text);
  transition: background-color 0.2s ease, color 0.2s ease;
}

.subject-link:hover {
  background: #eef2f7;
  color: var(--nav-accent);
}

.navbar-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.navbar-icon img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
  display: block;
}

.navbar-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--nav-text);
}

.navbar-center {
  flex: 1;
  display: flex;
  justify-content: center;
}

.navbar-nav {
  display: flex;
  gap: 28px;
  align-items: center;
  padding: 6px 12px;
  border-radius: var(--nav-radius);
  background-color: var(--nav-pill-bg);
  border: 1px solid var(--nav-border);
}

.nav-item {
  color: var(--nav-text);
  text-decoration: none;
  font-size: 16px;
  font-weight: 600;
  padding: 8px 12px;
  border-radius: var(--nav-item-radius);
  transition: all 0.2s ease;
}

.nav-item:hover,
.nav-item.active {
  background-color: #eef2f7;
  color: var(--nav-accent);
}

.nav-item-homework {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.nav-item-homework .nav-badge {
  font-size: 14px;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: 999px;
  background: #4a90e2;
  color: #ffffff;
  letter-spacing: 0.06em;
}

.nav-item-homework .nav-label {
  font-weight: 600;
}

.navbar-right {
  display: flex;
  align-items: center;
  gap: 12px;
}

.account-dropdown {
  position: relative;
}

.account-btn {
  background-color: transparent;
  border: 1px solid var(--nav-border);
  color: var(--nav-text);
  padding: 10px 16px;
  border-radius: 12px;
  cursor: pointer;
  font-weight: 600;
  transition: all 0.2s ease;
}

.account-btn:hover {
  border-color: var(--nav-accent);
  color: var(--nav-accent);
  box-shadow: 0 4px 10px rgba(74, 144, 226, 0.18);
}

.account-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  background-color: #ffffff;
  border: 1px solid var(--nav-border);
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  min-width: 150px;
  display: none;
  flex-direction: column;
  z-index: 1001;
}

.account-menu.show { display: flex; }

.account-menu-item {
  background-color: transparent;
  border: none;
  color: var(--nav-text);
  padding: 12px 16px;
  text-align: left;
  cursor: pointer;
  font-size: 14px;
  transition: background-color 0.2s ease;
}

.account-menu-item:hover { background-color: #eef2f7; }

.account-menu-item:first-child {
  border-top-left-radius: 12px;
  border-top-right-radius: 12px;
}

.account-menu-item:last-child {
  border-bottom-left-radius: 12px;
  border-bottom-right-radius: 12px;
}