/*
============================================================
HEADER.CSS
============================================================
*/

header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(8, 13, 26, 0.85);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border-light);
    transition: background 0.3s ease, box-shadow 0.3s ease;
}

header.scrolled {
    background: rgba(8, 13, 26, 0.97);
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.5);
    border-bottom-color: var(--border-medium);
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 68px;
}

/* Logo */
.logo a {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--text-primary);
    transition: color 0.25s ease;
    letter-spacing: -0.02em;
}

.logo a span { color: var(--primary); }
.logo a:hover { color: var(--primary); }

/* Navigation */
nav ul {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

nav ul li a {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    position: relative;
    padding: 0.4rem 0;
    transition: color 0.25s ease;
    letter-spacing: 0.2px;
}

nav ul li a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    border-radius: 1px;
    transition: width 0.25s ease;
}

nav ul li a:hover { color: var(--text-primary); }
nav ul li a:hover::after,
nav ul li a.active::after { width: 100%; }

/* Hamburger */
.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    padding: 8px;
    border-radius: 6px;
}

.hamburger span {
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    transition: all 0.3s ease;
    border-radius: 2px;
    display: block;
}

.hamburger.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.hamburger.active span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.hamburger.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* Menu Overlay */
.menu-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.55);
    z-index: 998;
    opacity: 0;
    transition: opacity 0.3s ease;
    backdrop-filter: blur(4px);
}

.menu-overlay.active { opacity: 1; }

/* ── Tablet & Mobile (≤ 768px) ── */
@media (max-width: 768px) {
    header .container { height: 64px; }

    .hamburger { display: flex; }

    .menu-overlay { display: block; pointer-events: none; }
    .menu-overlay.active { pointer-events: all; }

    nav {
        position: fixed;
        top: 64px;
        left: 0;
        right: 0;
        width: 100%;
        background: rgba(12, 17, 32, 0.98);
        backdrop-filter: blur(16px);
        -webkit-backdrop-filter: blur(16px);
        border-bottom: 1px solid var(--border-medium);
        z-index: 999;
        visibility: hidden;
        transform: translateY(-8px);
        opacity: 0;
        transition: transform 0.25s ease, opacity 0.25s ease, visibility 0.25s ease;
        box-shadow: 0 12px 32px rgba(0, 0, 0, 0.5);
    }

    nav.active {
        visibility: visible;
        transform: translateY(0);
        opacity: 1;
    }

    nav ul {
        flex-direction: column;
        gap: 0;
        padding: 0.5rem 0 1rem;
        text-align: center;
    }

    nav ul li {
        border-bottom: 1px solid var(--border-light);
    }

    nav ul li:last-child { border-bottom: none; }

    nav ul li a {
        display: block;
        padding: 1rem 2rem;
        font-size: 1rem;
        color: var(--text-secondary);
    }

    nav ul li a:hover { color: var(--primary); }
    nav ul li a::after { display: none; }
}