:root {
    --i4-ink: #070914;
    --i4-muted: #606b80;
    --i4-line: rgba(7, 9, 20, 0.12);
    --i4-blue: #2563eb;
}

body[data-lang="zh"] .i4-header [data-i4-en],
body[data-lang="en"] .i4-header [data-i4-zh] {
    display: none !important;
}

.i4-header,
.i4-header * {
    box-sizing: border-box;
}

.i4-header {
    position: fixed;
    z-index: 90;
    top: 0;
    left: 0;
    right: 0;
    width: 100%;
    min-height: 88px;
    padding: 16px 0 !important;
    border-bottom: 1px solid rgba(226, 232, 240, 0.18);
    background: rgba(255, 255, 255, 0.48);
    box-shadow: 0 1px 0 rgba(255, 255, 255, 0.7) inset, 0 18px 55px rgba(15, 23, 42, 0.06);
    backdrop-filter: blur(34px) saturate(1.5);
    -webkit-backdrop-filter: blur(34px) saturate(1.5);
}

.i4-header a {
    color: inherit;
    text-decoration: none;
}

.i4-header button {
    font: inherit;
}

.i4-header__inner {
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    gap: 24px;
    width: min(1280px, 100%);
    min-height: 56px;
    margin: 0 auto;
    padding: 0 24px;
}

.i4-logo {
    display: inline-flex;
    align-items: center;
    min-width: 0;
}

.i4-logo img {
    display: block;
    width: auto;
    height: 56px;
    max-height: 56px;
    object-fit: contain;
}

.i4-nav {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 32px;
    color: #475569;
    font-size: 0.875rem;
    font-weight: 500;
}

.i4-nav-link {
    position: relative;
    transition: color 0.2s ease, transform 0.2s ease;
}

.i4-nav-link::after {
    content: "";
    position: absolute;
    left: 0;
    bottom: -4px;
    width: 0;
    height: 2px;
    background: var(--i4-blue);
    transition: width 0.3s ease;
}

.i4-nav-link:hover,
.i4-nav-link[aria-current="page"] {
    color: #1d4ed8;
}

.i4-nav-link:hover {
    transform: translateY(-1px);
}

.i4-nav-link:hover::after,
.i4-nav-link[aria-current="page"]::after {
    width: 100%;
}

.i4-nav-dropdown {
    position: relative;
}

.i4-nav-dropdown__panel {
    position: absolute;
    z-index: 100;
    top: 100%;
    left: 50%;
    min-width: 9rem;
    margin-top: 0.35rem;
    padding: 0.35rem 0;
    border: 1px solid rgba(226, 232, 240, 0.9);
    border-radius: 0.75rem;
    background: rgba(255, 255, 255, 0.98);
    box-shadow: 0 18px 48px rgba(15, 23, 42, 0.12);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateX(-50%) translateY(0.35rem);
    transition: opacity 0.16s ease, transform 0.16s ease, visibility 0.16s ease;
}

.i4-nav-dropdown:hover .i4-nav-dropdown__panel,
.i4-nav-dropdown:focus-within .i4-nav-dropdown__panel {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateX(-50%) translateY(0);
}

.i4-nav-dropdown__item {
    display: block;
    padding: 0.5rem 1rem;
    color: #475569;
    font-size: 0.875rem;
    font-weight: 500;
    white-space: nowrap;
    transition: background 0.15s ease, color 0.15s ease;
}

.i4-nav-dropdown__item:hover {
    background: #eff6ff;
    color: #1d4ed8;
}

.i4-nav-dropdown__item[aria-current="page"] {
    background: #eff6ff;
    color: #1d4ed8;
    font-weight: 700;
}

.i4-actions {
    display: inline-flex;
    align-items: center;
    gap: 12px;
}

.i4-lang {
    display: inline-flex !important;
    align-items: center;
    justify-content: center;
    flex: 0 0 42px;
    width: 42px !important;
    height: 42px !important;
    min-width: 42px;
    min-height: 42px;
    padding: 0 !important;
    border: 1px solid var(--i4-line);
    border-radius: 999px;
    background: #fff;
    color: var(--i4-muted);
    cursor: pointer;
    font-size: 0.82rem !important;
    font-weight: 900 !important;
    line-height: 1 !important;
}

.i4-lang.is-active {
    background: var(--i4-ink) !important;
    color: #fff !important;
}

.i4-menu-toggle {
    display: none;
    position: relative;
    z-index: 120;
    width: 44px;
    height: 44px;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    gap: 3px;
    padding: 0;
    border: 1px solid rgba(203, 213, 225, 0.82);
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.72);
    color: var(--i4-ink);
    box-shadow: 0 10px 24px rgba(15, 23, 42, 0.08), inset 0 1px 0 rgba(255, 255, 255, 0.82);
    -webkit-backdrop-filter: blur(14px) saturate(1.2);
    backdrop-filter: blur(14px) saturate(1.2);
}

.i4-menu-toggle span {
    display: block;
    width: 14px;
    height: 2px;
    border-radius: 999px;
    background: currentColor;
    transition: transform 220ms ease-out, opacity 220ms ease-out;
}

body.i4-menu-open .i4-menu-toggle span:nth-child(1) {
    transform: translateY(5px) rotate(45deg);
}

body.i4-menu-open .i4-menu-toggle span:nth-child(2) {
    opacity: 0;
}

body.i4-menu-open .i4-menu-toggle span:nth-child(3) {
    transform: translateY(-5px) rotate(-45deg);
}

.i4-contact {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 48px !important;
    padding: 0 24px !important;
    border: 0;
    border-radius: 999px !important;
    background: linear-gradient(135deg, #3b82f6 0%, #7c3aed 100%) !important;
    color: #fff !important;
    font-size: 0.875rem !important;
    font-weight: 600 !important;
    line-height: 1.25 !important;
    white-space: nowrap;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.i4-contact:hover {
    box-shadow: 0 0 20px rgba(59, 130, 246, 0.4);
    color: #fff;
    transform: translateY(-2px);
}

@media (max-width: 1180px) {
    .i4-header__inner {
        position: relative;
        grid-template-columns: auto auto;
    }

    .i4-nav {
        position: absolute;
        top: calc(100% + 10px);
        left: 12px;
        right: 12px;
        display: grid;
        gap: 2px;
        width: auto;
        max-height: calc(100vh - 108px);
        overflow-y: auto;
        overscroll-behavior: contain;
        padding: 12px;
        border: 1px solid rgba(226, 232, 240, 0.9);
        border-radius: 18px;
        background: rgba(255, 255, 255, 0.96);
        box-shadow: 0 24px 70px rgba(15, 23, 42, 0.14);
        opacity: 0;
        visibility: hidden;
        pointer-events: none;
        transform: translateY(-8px);
        transition: opacity 180ms ease, transform 180ms ease, visibility 180ms ease;
        backdrop-filter: blur(22px) saturate(1.35);
        -webkit-backdrop-filter: blur(22px) saturate(1.35);
    }

    body.i4-menu-open .i4-nav {
        opacity: 1;
        visibility: visible;
        pointer-events: auto;
        transform: translateY(0);
    }

    .i4-nav-link,
    .i4-nav-dropdown__trigger {
        display: block;
        padding: 10px 12px;
        border-radius: 12px;
        white-space: nowrap;
    }

    .i4-nav-link::after {
        display: none;
    }

    .i4-nav-dropdown__panel {
        position: static;
        width: 100%;
        min-width: 0;
        margin: 2px 0 4px;
        padding: 4px;
        border-radius: 12px;
        background: rgba(239, 246, 255, 0.78);
        box-shadow: none;
        opacity: 1;
        visibility: visible;
        pointer-events: auto;
        transform: none;
    }

    .i4-nav-dropdown__item {
        padding: 9px 12px 9px 22px;
        border-radius: 10px;
        white-space: nowrap;
    }

    .i4-actions {
        justify-self: end;
    }

    .i4-menu-toggle {
        display: inline-flex;
        flex: 0 0 44px;
    }
}

@media (max-width: 760px) {
    .i4-header {
        min-height: 68px;
        padding: 10px 0 !important;
    }

    .i4-header__inner {
        min-height: 48px;
        gap: 8px;
        padding: 0 12px;
    }

    .i4-logo img {
        height: 42px;
        max-height: 42px;
    }

    .i4-contact {
        display: none;
    }

    .i4-lang {
        flex-basis: 38px;
        width: 38px !important;
        height: 38px !important;
        min-width: 38px;
        min-height: 38px;
    }

    .i4-nav {
        top: calc(100% + 8px);
        left: 10px;
        right: 10px;
        max-height: calc(100vh - 86px);
    }
}

@media (max-width: 560px) {
    .i4-logo img {
        height: 34px;
        max-height: 34px;
    }

    .i4-lang {
        flex-basis: 34px;
        width: 34px !important;
        height: 34px !important;
        min-width: 34px;
        min-height: 34px;
        font-size: 0.78rem !important;
    }

    .i4-actions {
        gap: 6px;
    }

    .i4-menu-toggle {
        flex-basis: 38px;
        width: 38px;
        height: 38px;
    }

    .i4-menu-toggle span {
        width: 13px;
    }

    .i4-nav {
        left: 8px;
        right: 8px;
        padding: 10px;
    }

    .i4-nav-link,
    .i4-nav-dropdown__trigger {
        padding: 9px 10px;
    }

    .i4-nav-dropdown__item {
        padding: 8px 10px 8px 20px;
    }
}