#nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  border-bottom: 1px solid transparent;
  transition: background 0.25s, border-color 0.25s, backdrop-filter 0.25s;
}
#nav.scrolled {
  background: var(--nav-bg);
  border-bottom-color: var(--border);
  box-shadow: 0 1px 16px rgba(0, 0, 0, 0.06);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.nav-in {
  display: flex;
  align-items: center;
  height: 62px;
}

.nav-logo {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}
.nav-logo img { height: 36px; width: auto; }
[data-theme="dark"] .nav-logo img { filter: invert(1); }

.nav-links {
  display: flex;
  align-items: center;
  gap: 2px;
  margin-left: auto;
}
.nav-links a {
  font-size: 14px;
  font-weight: 450;
  color: var(--fg-2);
  padding: 6px 12px;
  border-radius: var(--r-sm);
  transition: color 0.18s, background 0.18s;
}
.nav-links a:hover { color: var(--fg); background: var(--surface); }

.nav-right {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: 16px;
  flex-shrink: 0;
}

/* Theme toggle button */
.tbtn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--r-sm);
  border: 1px solid var(--border);
  background: transparent;
  cursor: pointer;
  color: var(--fg-2);
  transition: color 0.18s, background 0.18s;
}
.tbtn:hover { color: var(--fg); background: var(--surface); }
.tbtn svg { width: 15px; height: 15px; }

/* Sun/moon icon visibility controlled by theme */
.i-sun  { display: none; }
.i-moon { display: block; }
[data-theme="dark"] .i-sun  { display: block; }
[data-theme="dark"] .i-moon { display: none; }

/* Hamburger */
.ham {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4.5px;
  cursor: pointer;
  padding: 8px;
  border: none;
  background: transparent;
  margin-left: auto;
}
.ham span {
  display: block;
  width: 20px;
  height: 1.5px;
  background: var(--fg);
  border-radius: 1px;
  transition: transform 0.2s, opacity 0.2s;
}

/* Mobile drawer */
.drawer {
  display: none;
  position: fixed;
  top: 62px; left: 0; right: 0;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  padding: 12px 28px 24px;
  z-index: 999;
}
.drawer.open { display: block; }
.drawer a {
  display: block;
  font-size: 16px;
  font-weight: 450;
  color: var(--fg-2);
  padding: 13px 0;
  border-bottom: 1px solid var(--border-sub);
  transition: color 0.18s;
}
.drawer a:last-of-type { border-bottom: none; }
.drawer a:hover { color: var(--fg); }
.drawer .btn { margin-top: 16px; width: 100%; justify-content: center; }