:root {
    --portal-topbar-height: 68px;
    --portal-topbar-bg: rgba(255, 255, 255, 0.85);
    --portal-topbar-border: rgba(0, 0, 0, 0.06);
    --portal-nav-color: #4b5563;
    --portal-nav-hover-color: #111827;
    --portal-nav-hover-bg: rgba(0, 0, 0, 0.04);
    --portal-nav-active-color: #111827;
    --portal-nav-active-bg: rgba(37, 99, 235, 0.08);
    --portal-menu-bg: #ffffff;
    --portal-menu-color: #1f2937;
    --portal-toggle-bg: #d1d5db;
    --portal-toggle-dot: #ffffff;
}

[data-theme="dark"] {
    --portal-topbar-bg: rgba(18, 18, 24, 0.9);
    --portal-topbar-border: rgba(255, 255, 255, 0.08);
    --portal-nav-color: #9ca3af;
    --portal-nav-hover-color: #f3f4f6;
    --portal-nav-hover-bg: rgba(255, 255, 255, 0.06);
    --portal-nav-active-color: #f3f4f6;
    --portal-nav-active-bg: rgba(37, 99, 235, 0.18);
    --portal-menu-bg: #0b0d17;
    --portal-menu-color: #e5e7eb;
    --portal-toggle-bg: #374151;
    --portal-toggle-dot: #e5e7eb;
}

html { scroll-padding-top: var(--portal-topbar-height); }
body.portal-shell-page { padding-top: var(--portal-topbar-height); }

.portal-topbar,
.portal-topbar * { box-sizing: border-box; }

.portal-topbar {
    position: fixed;
    inset: 0 0 auto 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--portal-topbar-height);
    padding: 0 3rem;
    background: var(--portal-topbar-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--portal-topbar-border);
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "PingFang SC", "Microsoft YaHei", sans-serif;
    transition: background 0.3s ease, border-color 0.3s ease;
}

.portal-nav-links { display: flex; align-items: center; gap: 0.5rem; }
.portal-nav-links a {
    position: relative;
    padding: 0.45rem 1rem;
    border-radius: 9999px;
    color: var(--portal-nav-color);
    font-size: 0.95rem;
    font-weight: 500;
    line-height: 1.5;
    text-decoration: none;
    white-space: nowrap;
    transition: color 0.25s ease, background 0.25s ease, transform 0.2s ease;
}
.portal-nav-links a::after {
    content: "";
    position: absolute;
    left: 50%;
    bottom: 2px;
    width: 18px;
    height: 3px;
    border-radius: 2px;
    background: linear-gradient(135deg, #2563eb, #7c3aed);
    transform: translateX(-50%) scaleX(0);
    transition: transform 0.25s ease;
}
.portal-nav-links a:hover { color: var(--portal-nav-hover-color); background: var(--portal-nav-hover-bg); transform: translateY(-1px); }
.portal-nav-links a.active { color: var(--portal-nav-active-color); background: var(--portal-nav-active-bg); }
.portal-nav-links a.active::after { transform: translateX(-50%) scaleX(1); }

.portal-topbar-right,
.portal-settings-panel,
.portal-lang-wrapper,
.portal-theme-toggle { display: flex; align-items: center; }
.portal-topbar-right { flex-shrink: 0; gap: 1rem; }
.portal-settings-toggle { display: none; }
.portal-settings-panel { gap: 1rem; }
.portal-lang-wrapper { gap: 0.3rem; }
.portal-lang-icon,
.portal-theme-icon { font-size: 1.1rem; line-height: 1; pointer-events: none; }

.portal-lang-select {
    width: auto;
    padding: 0.35rem 1.8rem 0.35rem 0.5rem;
    border: 1px solid var(--portal-topbar-border);
    border-radius: 8px;
    appearance: none;
    -webkit-appearance: none;
    background-color: transparent;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236b7280' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.45rem center;
    color: var(--portal-nav-color);
    font-family: inherit;
    font-size: 0.85rem;
    font-weight: 500;
    line-height: 1.5;
    cursor: pointer;
    transition: border-color 0.2s ease, color 0.2s ease;
}
.portal-lang-select:hover { border-color: var(--portal-nav-color); }
.portal-lang-select:focus { outline: none; border-color: #2563eb; box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.15); }
.portal-lang-select option { background: var(--portal-menu-bg); color: var(--portal-menu-color); }

.portal-theme-toggle { flex-shrink: 0; gap: 0.35rem; cursor: pointer; user-select: none; }
.portal-theme-toggle input { display: none; }
.portal-slider-track {
    position: relative;
    width: 48px;
    height: 26px;
    border-radius: 999px;
    background: var(--portal-toggle-bg);
    transition: background 0.3s ease;
}
.portal-slider-track::after {
    content: "";
    position: absolute;
    top: 2px;
    left: 2px;
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: var(--portal-toggle-dot);
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.2);
    transition: transform 0.3s ease, background 0.3s ease;
}
.portal-theme-toggle input:checked + .portal-slider-track { background: linear-gradient(135deg, #2563eb, #7c3aed); }
.portal-theme-toggle input:checked + .portal-slider-track::after { transform: translateX(22px); }

body.portal-shell-page .product-explorer,
body.portal-shell-page .hero {
    height: auto;
    min-height: calc(100vh - var(--portal-topbar-height));
}

@media (max-width: 768px) {
    :root { --portal-topbar-height: 58px; }
    .portal-topbar { padding: 0.55rem 0.65rem; gap: 0.35rem; }
    .portal-nav-links {
        flex: 1;
        min-width: 0;
        gap: 0.15rem;
        overflow-x: auto;
        scrollbar-width: none;
        -webkit-overflow-scrolling: touch;
    }
    .portal-nav-links::-webkit-scrollbar { display: none; }
    .portal-nav-links a { padding: 0.35rem 0.55rem; font-size: 0.8rem; }
    .portal-nav-links a::after { width: 14px; height: 2px; }
    .portal-topbar-right { position: relative; display: block; }
    .portal-settings-toggle {
        display: grid;
        place-items: center;
        width: 38px;
        height: 38px;
        padding: 0;
        border: 1px solid var(--portal-topbar-border);
        border-radius: 10px;
        background: var(--portal-nav-hover-bg);
        color: var(--portal-nav-color);
        font: inherit;
        font-size: 1.05rem;
        cursor: pointer;
        transition: color 0.2s ease, background 0.2s ease, transform 0.2s ease;
    }
    .portal-settings-toggle:hover,
    .portal-settings-toggle[aria-expanded="true"] { color: var(--portal-nav-active-color); background: var(--portal-nav-active-bg); }
    .portal-settings-toggle[aria-expanded="true"] { transform: rotate(30deg); }
    .portal-settings-panel {
        position: absolute;
        top: calc(100% + 10px);
        right: 0;
        z-index: 20;
        gap: 0.75rem;
        min-width: 230px;
        padding: 0.75rem;
        border: 1px solid var(--portal-topbar-border);
        border-radius: 14px;
        background: var(--portal-topbar-bg);
        backdrop-filter: blur(16px);
        -webkit-backdrop-filter: blur(16px);
        box-shadow: 0 12px 30px rgba(0, 0, 0, 0.16);
        opacity: 0;
        visibility: hidden;
        transform: translateY(-6px) scale(0.98);
        transform-origin: top right;
        transition: opacity 0.18s ease, visibility 0.18s ease, transform 0.18s ease;
    }
    .portal-topbar-right.open .portal-settings-panel { opacity: 1; visibility: visible; transform: translateY(0) scale(1); }
    .portal-lang-wrapper { padding-right: 0.8rem; border-right: 1px solid var(--portal-topbar-border); }
    .portal-lang-select { width: 108px; padding-block: 0.3rem; border: 0; }
    .portal-slider-track { width: 40px; height: 22px; }
    .portal-slider-track::after { width: 18px; height: 18px; }
    .portal-theme-toggle input:checked + .portal-slider-track::after { transform: translateX(18px); }
    body.portal-shell-page .product-explorer,
    body.portal-shell-page .hero { min-height: calc(100svh - var(--portal-topbar-height)); }
}

@media (max-width: 420px) {
    .portal-topbar { padding-inline: 0.6rem; }
}