header {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  border-bottom: 1px solid var(--border);
  background: var(--glass);
  backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 10;
  margin-right: calc(-1 * (100vw - 100%));
}
html {
  overflow-x: hidden;
  overflow-y: scroll;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: 85%;
  margin: 0 auto;
  padding: 0.75rem 4rem;
}

.logo {
  width: 4rem;
  height: auto;
  transition:
    transform 0.2s,
    filter 0.2s;
}
.logo:hover {
  transform: scale(1.08);
  filter: drop-shadow(0 0 6px rgba(255, 255, 255, 0.5));
}

header nav ul {
  display: flex;
  gap: 2rem;
}

.nav-link {
  position: relative;
  color: var(--text);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.2s;
}
.nav-link:hover {
  color: var(--green);
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -3px;
  width: 0;
  height: 2px;
  background: var(--green);
  transition: width 0.3s;
}
.nav-link:hover::after {
  width: 100%;
}

/* ── HAMBURGER ── */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 0.25rem;
  background: none;
  border: none;
}
.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition:
    transform 0.3s,
    opacity 0.3s;
}
.nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}
.nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

@media (max-width: 600px) {
  .header-inner {
    width: 100%;
    padding: 0.75rem 1.25rem;
  }

  .nav-toggle {
    display: flex;
  }

  header nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--glass);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
    padding: 1rem 1.25rem;
  }
  header nav.open {
    display: block;
  }
  header nav ul {
    flex-direction: column;
    gap: 1.25rem;
  }
}