*, *::before, *::after {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    margin: 0;
    overflow-x: hidden;
}

::selection {
    background: rgba(79, 209, 197, 0.3);
    color: #fff;
}

::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: #0A1628;
}

::-webkit-scrollbar-thumb {
    background: rgba(79, 209, 197, 0.3);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: rgba(79, 209, 197, 0.5);
}

/* Mobile menu */
#mobile-menu.open {
    opacity: 1;
    pointer-events: all;
}

#mobile-menu.open .mobile-link {
    animation: fadeUp 0.4s ease forwards;
    opacity: 1;
}

#mobile-menu .mobile-link:nth-child(1) { animation-delay: 0.05s; }
#mobile-menu .mobile-link:nth-child(2) { animation-delay: 0.1s; }
#mobile-menu .mobile-link:nth-child(3) { animation-delay: 0.15s; }
#mobile-menu .mobile-link:nth-child(4) { animation-delay: 0.2s; }
#mobile-menu .mobile-link:nth-child(5) { animation-delay: 0.25s; }

@keyframes fadeUp {
    from { opacity: 0; transform: translateY(12px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Hamburger animation */
#menu-btn[aria-expanded="true"] .menu-line:first-child {
    transform: translateY(5px) rotate(45deg);
}

#menu-btn[aria-expanded="true"] .menu-line:nth-child(2) {
    opacity: 0;
    transform: scaleX(0);
}

#menu-btn[aria-expanded="true"] .menu-line:last-child {
    transform: translateY(-5px) rotate(-45deg);
    width: 1.5rem;
}

/* Scroll reveal (progressive enhancement) */
@media (prefers-reduced-motion: no-preference) {
    .reveal {
        opacity: 0;
        transform: translateY(24px);
        transition: opacity 0.7s ease, transform 0.7s ease;
    }

    .reveal.revealed {
        opacity: 1;
        transform: translateY(0);
    }

    .reveal-delay-1 { transition-delay: 0.1s; }
    .reveal-delay-2 { transition-delay: 0.2s; }
    .reveal-delay-3 { transition-delay: 0.3s; }
}

@media (prefers-reduced-motion: reduce) {
    .reveal {
        opacity: 1;
        transform: none;
    }
}

/* Header scroll state */
#site-header.scrolled {
    background: rgba(5, 13, 26, 0.92);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

/* Focus styles */
a:focus-visible, button:focus-visible, input:focus-visible, textarea:focus-visible {
    outline: 2px solid #4FD1C5;
    outline-offset: 2px;
    border-radius: 4px;
}

/* Form validation */
input:invalid:not(:placeholder-shown), textarea:invalid:not(:placeholder-shown) {
    border-color: rgba(239, 68, 68, 0.5);
}

input:valid:not(:placeholder-shown), textarea:valid:not(:placeholder-shown) {
    border-color: rgba(79, 209, 197, 0.3);
}