/* 多语言页面顶部导航共享样式；changelog 的浅色导航是基础页基准，首页只切换深色变量。 */
:root {
    --site-header-radius: 18px;
    --site-header-top: 15px;
}

/* 用页面底色遮住导航上方的缝隙，保留导航圆角，不拦截点击。 */
body::before {
    position: fixed;
    top: 0;
    right: 0;
    left: 0;
    z-index: 29;
    height: var(--site-header-top);
    background: var(--content-bg, var(--bg-color, var(--bg, #ffffff)));
    pointer-events: none;
    content: "";
}

.site-header {
    --site-header-bg: var(
        --content-header-bg,
        var(--header-bg, var(--bg-panel, rgba(255, 255, 255, 0.86)))
    );
    --site-header-line: var(
        --content-line,
        var(--header-line, var(--line, rgba(0, 0, 0, 0.08)))
    );
    --site-header-line-strong: var(
        --content-line-strong,
        var(--header-line-strong, var(--line-strong, rgba(0, 0, 0, 0.14)))
    );
    --site-header-text: var(
        --content-text,
        var(--header-text, var(--text, var(--text-color, #1d1d1f)))
    );
    --site-header-text-soft: var(
        --content-text-soft,
        var(--header-text-soft, var(--text-soft, var(--sub-text, rgba(29, 29, 31, 0.62))))
    );
    --site-header-panel: var(
        --content-bg-soft,
        var(--card-bg, var(--bg-elevated, #ffffff))
    );
    --site-header-accent: var(
        --content-accent,
        #4e87ff
    );
    position: fixed;
    top: var(--site-header-top);
    left: 50%;
    z-index: 30;
    width: min(calc(100% - 20px), 1180px);
    color: var(--site-header-text);
    transform: translateX(-50%);
}

/* 在导航下层填充顶部圆弧外侧，完整保留导航背景和边框。 */
.site-header::before,
.site-header::after {
    position: absolute;
    top: 0;
    z-index: -1;
    width: var(--site-header-radius);
    height: var(--site-header-radius);
    pointer-events: none;
    content: "";
}

.site-header::before {
    left: 0;
    background: radial-gradient(
        circle at bottom right,
        transparent calc(var(--site-header-radius) - 0.5px),
        var(--content-bg, var(--bg-color, var(--bg, #ffffff))) var(--site-header-radius)
    );
}

.site-header::after {
    right: 0;
    background: radial-gradient(
        circle at bottom left,
        transparent calc(var(--site-header-radius) - 0.5px),
        var(--content-bg, var(--bg-color, var(--bg, #ffffff))) var(--site-header-radius)
    );
}

.site-header--home {
    --site-header-bg: rgba(12, 13, 17, 0.58);
    --site-header-line: rgba(255, 255, 255, 0.12);
    --site-header-line-strong: rgba(255, 255, 255, 0.2);
    --site-header-text: #ffffff;
    --site-header-text-soft: rgba(255, 255, 255, 0.62);
    --site-header-panel: #0f1115;
    --site-header-accent: #4e87ff;
}

.site-header .container {
    position: relative;
    z-index: 0;
    width: 100%;
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    gap: 28px;
    min-height: 56px;
    padding: 0 10px;
    border: 1px solid transparent;
    border-radius: var(--site-header-radius);
    background: transparent;
    box-shadow: none;
    -webkit-backdrop-filter: none;
    backdrop-filter: none;
}

/* 背景默认透明，避免脚本执行前闪现；滚动后独立渐显。 */
.site-header .container::before {
    position: absolute;
    inset: -1px;
    z-index: -1;
    border: 1px solid var(--site-header-line);
    border-radius: inherit;
    background: var(--site-header-bg);
    box-shadow: 0 12px 28px rgba(15, 23, 42, 0.09);
    -webkit-backdrop-filter: blur(24px) saturate(150%);
    backdrop-filter: blur(24px) saturate(150%);
    opacity: 0;
    pointer-events: none;
    content: "";
    transition: opacity 240ms ease;
}

.site-header--home .container::before {
    box-shadow: 0 18px 40px rgba(0, 0, 0, 0.22);
}

.site-header.is-scrolled .container::before {
    opacity: 1;
}

@media (prefers-reduced-motion: reduce) {
    .site-header .container::before {
        transition: none;
    }
}

.brand-link {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    min-width: 0;
    color: var(--site-header-text);
}

.brand-mark {
    width: 32px;
    height: 32px;
    flex: 0 0 32px;
    border: 1px solid var(--site-header-line-strong);
    border-radius: 8px;
}

.site-header:not(.site-header--home) .brand-mark {
    border: 0;
}

.brand-wordmark {
    width: 53px;
    height: auto;
    opacity: 0.96;
}

.site-header--home .brand-wordmark {
    filter: brightness(0) invert(1);
}

.site-header:not(.site-header--home) .brand-wordmark {
    filter: none;
}

.top-nav {
    position: absolute;
    left: 50%;
    display: inline-flex;
    align-items: center;
    gap: 45px;
    justify-self: center;
    transform: translateX(-50%);
}

.top-nav > a,
.top-nav > details > summary {
    color: var(--site-header-text-soft);
    font: inherit;
    font-size: 13px;
    font-weight: 400;
    line-height: 1;
    letter-spacing: normal;
    white-space: nowrap;
}

.top-nav > a,
.top-nav > details > summary,
.mobile-menu-panel > a,
.mobile-nav-dropdown > summary {
    cursor: pointer;
}

.top-nav > a:hover,
.top-nav > a:focus-visible,
.top-nav > details > summary:hover,
.top-nav > details > summary:focus-visible,
.top-nav > a.is-active {
    color: var(--site-header-text);
}

.top-nav > a.is-active,
.top-nav-dropdown__panel a.is-active,
.mobile-menu-panel > a.is-active,
.mobile-nav-dropdown__panel a.is-active {
    font-weight: 600;
}

.top-nav-dropdown,
.mobile-nav-dropdown {
    position: relative;
}

.top-nav-dropdown > summary,
.mobile-nav-dropdown > summary {
    position: relative;
    top: -1px;
    display: inline-flex;
    align-items: center;
    list-style: none;
}

.top-nav-dropdown > summary::-webkit-details-marker,
.mobile-nav-dropdown > summary::-webkit-details-marker {
    display: none;
}

.top-nav-dropdown > summary::after,
.mobile-nav-dropdown > summary::after {
    display: inline-block;
    width: 9px;
    height: 9px;
    flex-shrink: 0;
    margin-left: 6px;
    background-color: var(--site-header-text-soft);
    -webkit-mask: url("icons/chevron-down.svg") center / contain no-repeat;
    mask: url("icons/chevron-down.svg") center / contain no-repeat;
    content: "";
    transform: translateY(0.5px);
    transform-origin: center;
    transition: transform 180ms ease;
}

.top-nav-dropdown[open] > summary::after,
.mobile-nav-dropdown[open] > summary::after {
    transform: translateY(2px) rotate(180deg);
}

.top-nav-dropdown.is-closing > summary::after {
    transform: translateY(0.5px);
}

/* 中文、日文、韩文使用独立偏移，保留已校准的上下箭头位置。 */
.site-header:lang(zh) .top-nav-dropdown > summary::after,
.site-header:lang(zh) .mobile-nav-dropdown > summary::after,
.site-header:lang(ja) .top-nav-dropdown > summary::after,
.site-header:lang(ja) .mobile-nav-dropdown > summary::after,
.site-header:lang(ko) .top-nav-dropdown > summary::after,
.site-header:lang(ko) .mobile-nav-dropdown > summary::after {
    transform: translateY(0);
}

.site-header:lang(zh) .top-nav-dropdown[open] > summary::after,
.site-header:lang(zh) .mobile-nav-dropdown[open] > summary::after,
.site-header:lang(ja) .top-nav-dropdown[open] > summary::after,
.site-header:lang(ja) .mobile-nav-dropdown[open] > summary::after,
.site-header:lang(ko) .top-nav-dropdown[open] > summary::after,
.site-header:lang(ko) .mobile-nav-dropdown[open] > summary::after {
    transform: translateY(1px) rotate(180deg);
}

.site-header:lang(zh) .top-nav-dropdown.is-closing > summary::after,
.site-header:lang(ja) .top-nav-dropdown.is-closing > summary::after,
.site-header:lang(ko) .top-nav-dropdown.is-closing > summary::after {
    transform: translateY(0);
}

.top-nav-dropdown__panel {
    position: absolute;
    top: calc(100% + 13px);
    left: 50%;
    display: grid;
    min-width: 190px;
    gap: 4px;
    padding: 10px;
    border: 1px solid var(--site-header-line);
    border-radius: 12px;
    background: var(--site-header-panel);
    box-shadow: 0 18px 40px rgba(0, 0, 0, 0.14);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateX(-50%) translateY(-6px);
    transition: opacity 180ms ease, transform 180ms ease, visibility 0s linear 180ms;
}

.top-nav-dropdown[open] > .top-nav-dropdown__panel {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateX(-50%) translateY(0);
    transition-delay: 0s;
}

.top-nav-dropdown.is-closing > .top-nav-dropdown__panel {
    opacity: 0;
    visibility: visible;
    pointer-events: auto;
    transform: translateX(-50%) translateY(-6px);
    transition-delay: 0s;
}

.top-nav-dropdown__panel a,
.mobile-nav-dropdown__panel a {
    display: flex;
    align-items: center;
    min-height: 34px;
    padding: 0 10px;
    border-radius: 8px;
    color: var(--site-header-text-soft);
    font-size: 13px;
    line-height: 1.25;
    white-space: nowrap;
}

.top-nav-dropdown__panel a:hover,
.top-nav-dropdown__panel a:focus-visible,
.top-nav-dropdown__panel a.is-active,
.mobile-nav-dropdown__panel a:hover,
.mobile-nav-dropdown__panel a:focus-visible,
.mobile-nav-dropdown__panel a.is-active {
    color: var(--site-header-text);
    background: var(--site-header-line);
}

.header-actions {
    position: absolute;
    top: 50%;
    right: 0;
    display: inline-flex;
    align-items: center;
    gap: 26px;
    padding-right: 10px;
    transform: translateY(-50%);
}

.language-picker {
    position: relative;
    display: inline-flex;
    align-items: center;
}

.static-lang {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 0;
    border: 0;
    color: var(--site-header-text-soft);
    background: transparent;
    font: inherit;
    font-size: 12px;
    font-weight: 400;
    line-height: 1;
    cursor: pointer;
}

.static-lang:hover,
.static-lang:focus-visible {
    color: var(--site-header-text);
}

.static-lang svg {
    width: 14.4px;
    height: 14.4px;
    opacity: 0.85;
}

.lang-menu {
    position: absolute;
    top: calc(100% + 6px);
    right: 0;
    display: flex;
    flex-direction: column;
    gap: 4px;
    min-width: 160px;
    padding: 6px;
    border: 1px solid var(--site-header-line);
    border-radius: 14px;
    background: var(--site-header-panel);
    box-shadow: 0 18px 32px 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;
}

.lang-menu::before {
    position: absolute;
    right: 0;
    bottom: 100%;
    left: 0;
    height: 12px;
    content: "";
}

.language-picker:hover .lang-menu,
.language-picker:focus-within .lang-menu,
.language-picker.is-open .lang-menu {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateY(0);
}

.lang-option {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: 8px 10px;
    border-radius: 10px;
    color: var(--site-header-text);
    font-size: 13px;
    line-height: 1.2;
    white-space: nowrap;
}

.lang-option:hover,
.lang-option:focus-visible {
    color: var(--site-header-text);
    background: var(--site-header-line);
}

.lang-option.is-active {
    color: var(--site-header-text);
    background: var(--site-header-line);
    font-weight: 600;
}

.lang-option.is-active::after {
    display: none;
}

.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 36px;
    padding: 0 16px;
    border-radius: 10px;
    font-size: 13px;
    font-weight: 600;
    line-height: 1;
    white-space: nowrap;
}

.site-header .button-primary,
.feature-cta--download .button-primary {
    min-width: 120px;
    color: #ffffff;
    background: var(--site-header-accent, var(--content-accent, #4e87ff));
    box-shadow: none;
}

.site-header .button-primary:hover,
.site-header .button-primary:focus-visible,
.feature-cta--download .button-primary:hover,
.feature-cta--download .button-primary:focus-visible {
    filter: brightness(1.08);
}

.site-header .button-primary img,
.feature-cta--download .button-primary img {
    width: 14.04px;
    height: 18.11px;
}

.mobile-menu {
    display: none;
    position: relative;
    justify-self: end;
}

.mobile-menu > summary {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border: 1px solid var(--site-header-line);
    border-radius: 10px;
    background: transparent;
    cursor: pointer;
    list-style: none;
}

.mobile-menu > summary::-webkit-details-marker {
    display: none;
}

.mobile-menu > summary span,
.mobile-menu > summary::before,
.mobile-menu > summary::after {
    position: absolute;
    width: 14px;
    height: 1.5px;
    border-radius: 999px;
    background: var(--site-header-text);
    content: "";
}

.mobile-menu > summary::before {
    transform: translateY(-5px);
}

.mobile-menu > summary::after {
    transform: translateY(5px);
}

.mobile-menu[open] > summary span {
    opacity: 0;
}

.mobile-menu[open] > summary::before {
    transform: rotate(45deg);
}

.mobile-menu[open] > summary::after {
    transform: rotate(-45deg);
}

.mobile-menu-panel {
    position: absolute;
    top: calc(100% + 10px);
    right: 0;
    display: grid;
    gap: 4px;
    min-width: 180px;
    padding: 10px;
    border: 1px solid var(--site-header-line);
    border-radius: 14px;
    background: var(--site-header-panel);
    box-shadow: 0 18px 40px rgba(0, 0, 0, 0.14);
}

.mobile-menu-panel > a {
    display: flex;
    align-items: center;
    min-height: 36px;
    padding: 0 12px;
    border-radius: 10px;
    color: var(--site-header-text);
    font-size: 13px;
}

.mobile-menu-panel > a:hover,
.mobile-menu-panel > a:focus-visible,
.mobile-menu-panel > a.is-active {
    background: rgba(0, 113, 227, 0.08);
}

.mobile-nav-dropdown {
    display: grid;
    gap: 4px;
}

.mobile-nav-dropdown > summary {
    justify-content: space-between;
    min-height: 36px;
    padding: 0 12px;
    color: var(--site-header-text);
    font-size: 13px;
}

.mobile-nav-dropdown[open] > summary {
    background: var(--site-header-line);
}

.mobile-nav-dropdown__panel {
    display: grid;
    gap: 4px;
    padding: 0 0 4px 10px;
}

.mobile-nav-dropdown__panel a.nav-download,
.mobile-menu-panel > a.nav-download {
    color: #ffffff;
    background: var(--site-header-accent);
}

/* 译文较长，非英文页面在窄桌面提前折叠导航，保留英文版断点。 */
@media (min-width: 761px) and (max-width: 1160px) {
    .site-header:not(:lang(en)) .top-nav {
        display: none;
    }

    .site-header:not(:lang(en)) .mobile-menu {
        position: absolute;
        right: 10px;
        display: block;
    }

    .site-header:not(:lang(en)) .header-actions {
        padding-right: 58px;
    }
}

@media (max-width: 760px) {
    .site-header {
        width: min(calc(100% - 20px), 1160px);
    }

    .site-header .container {
        display: flex;
        gap: 12px;
        padding: 10px 10px 10px 12px;
    }

    .top-nav,
    .header-actions .button {
        display: none;
    }

    .header-actions {
        position: static;
        gap: 0;
        margin-left: auto;
        padding-right: 0;
        transform: none;
    }

    .mobile-menu {
        display: block;
        order: 3;
        margin-left: 12px;
    }
}

@media (max-width: 480px) {
    :root {
        --site-header-top: 0.7rem;
    }

    .site-header .container {
        gap: 8px;
    }

    .brand-link {
        gap: 8px;
    }

    .brand-mark {
        width: 30px;
        height: 30px;
        flex-basis: 30px;
    }
}