/* ============================================
   HEADER RESPONSIVE CSS
   Breakpoints:
   - SM (Small)    : ~480px   (모바일 세로)
   - MD (Medium)   : 481~768px (모바일 가로 / 소형 태블릿)
   - TB (Tablet)   : 769~1024px (태블릿)
   - LG (Large)    : 1025px~  (데스크탑)
   ============================================ */

/* ── Hamburger Toggle Button ── */
.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 44px;
    height: 44px;
    background: none;
    border: none;
    cursor: pointer;
    z-index: 200;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
}
.nav-toggle span {
    display: block;
    width: 22px;
    height: 1.5px;
    background: #111;
    transition: all 0.35s cubic-bezier(0.77, 0, 0.18, 1);
    position: relative;
}
.nav-toggle span:nth-child(1) { margin-bottom: 6px; }
.nav-toggle span:nth-child(3) { margin-top: 6px; }

/* Hamburger → X animation */
.nav-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
    background: #111;
}
.nav-toggle.active span:nth-child(2) {
    opacity: 0;
    transform: scaleX(0);
}
.nav-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
    background: #111;
}

/* ── Navbar scroll shrink (applied via JS) ── */
.navbar.scrolled {
    padding-top: 1rem;
    padding-bottom: 1rem;
    box-shadow: 0 1px 12px rgba(0,0,0,0.06);
}

/* ============================================
   LG — Large (1025px ~)
   Desktop default, no changes needed
   ============================================ */
@media (min-width: 1025px) {
    .nav-toggle { display: none !important; }
    .menu { display: flex !important; }
}

/* ============================================
   TB — Tablet (769px ~ 1024px)
   ============================================ */
@media (max-width: 1024px) and (min-width: 769px) {
    .navbar {
        padding: 1.4rem 4%;
    }
    .logo a {
        font-size: 1.35rem;
    }
    .menu {
        gap: 1.5rem;
        font-size: 0.8rem;
    }
    .menu a {
        padding: 0.3rem 0;
        position: relative;
    }
    .menu a::after {
        content: "";
        position: absolute;
        bottom: 0;
        left: 0;
        width: 0;
        height: 1.5px;
        background: #111;
        transition: width 0.3s ease;
    }
    .menu a:hover::after {
        width: 100%;
    }
}

/* ============================================
   MD — Medium (481px ~ 768px)
   Switch to hamburger menu
   ============================================ */
@media (max-width: 768px) {
    .navbar {
        padding: 1rem calc(4% + var(--page-gutter));
    }
    .logo a {
        font-size: 1.3rem;
    }

    .nav-toggle {
        display: flex;
    }

    /* Full-screen overlay menu */
    .menu {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100vh;
        height: 100dvh;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 0;
        z-index: 150;
        padding: 5rem 2rem;
        opacity: 0;
        transition: opacity 0.4s ease;
    }
    .menu.open {
        display: flex;
        opacity: 1;
        animation: menuSlideIn 0.4s cubic-bezier(0.16, 1, 0.3, 1) forwards;
    }
    @keyframes menuSlideIn {
        from {
            opacity: 0;
            transform: translateY(-20px);
        }
        to {
            opacity: 1;
            transform: none;
        }
    }

    .menu a {
        font-size: 1.4rem;
        font-weight: 600;
        letter-spacing: 0.08em;
        padding: 1rem 0;
        color: #111;
        opacity: 0;
        transform: translateY(15px);
        animation: menuItemIn 0.4s ease forwards;
        border-bottom: 1px solid rgba(0,0,0,0.06);
        width: 80%;
        text-align: center;
    }
    .menu.open a {
        opacity: 1;
        transform: none;
    }
    .menu.open a:nth-child(1) { animation-delay: 0.05s; }
    .menu.open a:nth-child(2) { animation-delay: 0.10s; }
    .menu.open a:nth-child(3) { animation-delay: 0.15s; }

    @keyframes menuItemIn {
        from {
            opacity: 0;
            transform: translateY(15px);
        }
        to {
            opacity: 1;
            transform: none;
        }
    }

    .menu a:last-child {
        border-bottom: none;
    }
    .menu a:hover {
        color: var(--accent-color);
    }
}

/* ============================================
   SM — Small (~ 480px)
   Tighter spacing, smaller elements
   ============================================ */
@media (max-width: 480px) {
    .navbar {
        padding: 0.85rem calc(4% + var(--page-gutter));
    }
    .logo a {
        font-size: 1.15rem;
        letter-spacing: 0.08em;
    }
    .nav-toggle {
        width: 38px;
        height: 38px;
    }
    .nav-toggle span {
        width: 18px;
        height: 1.5px;
    }
    .nav-toggle span:nth-child(1) { margin-bottom: 5px; }
    .nav-toggle span:nth-child(3) { margin-top: 5px; }

    .menu {
        padding: 4rem 1.5rem;
    }
    .menu a {
        font-size: 1.2rem;
        padding: 0.85rem 0;
        width: 90%;
    }
}