html { scroll-behavior: smooth; }

#hamburger.active .hamburger-line:nth-child(1) { transform: rotate(45deg) translate(4px, 4px); }
#hamburger.active .hamburger-line:nth-child(2) { opacity: 0; transform: scaleX(0); }
#hamburger.active .hamburger-line:nth-child(3) { transform: rotate(-45deg) translate(4px, -4px); }

#mobile-menu { max-height: 0; overflow: hidden; transition: max-height 0.3s ease; }
#mobile-menu.menu-open { display: block; max-height: 300px; }