/* =============================================
   HEADER & NAVIGATION
   ============================================= */

.header {
    position: fixed;
    top: 0; left: 0;
    width: 100%;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--glass-border);
    z-index: 1000;
    transition: all var(--transition-base);
}
.header.scroll-header { box-shadow: var(--shadow-md); }

.nav {
    height: var(--header-height);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav__logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    font-family: var(--font-code);
}
.logo-bracket { color: var(--primary-color); }

.nav__list {
    display: flex;
    gap: 2rem;
}

.nav__link {
    color: var(--text-secondary);
    font-weight: 500;
    transition: color var(--transition-fast);
    position: relative;
}
.nav__link::after {
    content: '';
    position: absolute;
    bottom: -0.5rem; left: 0;
    width: 0; height: 1px;
    background: var(--text-primary);
    transition: width var(--transition-base);
}
.nav__link:hover, .nav__link.active-link { color: var(--primary-color); }
.nav__link:hover::after, .nav__link.active-link::after { width: 100%; }

.nav__actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.theme-toggle {
    width: 40px; height: 40px;
    border-radius: 50%;
    background: var(--bg-secondary);
    color: var(--text-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-base);
}
.theme-toggle:hover {
    transform: rotate(20deg) scale(1.1);
    background: var(--primary-color);
    color: var(--bg-primary);
}

.nav__toggle, .nav__close {
    display: none;
    font-size: 1.5rem;
    color: var(--text-primary);
    cursor: pointer;
}

@media screen and (max-width: 768px) {
    .nav__menu {
        position: fixed;
        top: 0; right: -100%;
        width: 80%; height: 100vh;
        background: var(--bg-primary);
        padding: 6rem 2rem 2rem;
        transition: right var(--transition-base);
        box-shadow: var(--shadow-xl);
    }
    .nav__menu.show-menu { right: 0; }
    .nav__list { flex-direction: column; gap: 2rem; }
    .nav__link { font-size: 1.25rem; }
    .nav__close {
        display: block;
        position: absolute;
        top: 1.5rem; right: 1.5rem;
    }
    .nav__toggle { display: block; }
}