/* ========================================
   产品页二级锚点导航 — 三页统一深色 slate 风格
   ======================================== */

:root {
    --subnav-height: 52px;
    --subnav-stack-top: calc(var(--nav-offset, 72px) + env(safe-area-inset-top, 0px));
    --subnav-bg: rgba(15, 23, 42, 0.94);
    --subnav-border: rgba(148, 163, 184, 0.14);
    --subnav-shadow: 0 1px 3px rgba(0, 0, 0, 0.12);
    --subnav-label: #94a3b8;
    --subnav-link: #94a3b8;
    --subnav-link-hover: #cbd5e1;
    --subnav-link-active: #f1f5f9;
    --subnav-indicator: #94a3b8;
    --subnav-cta-border: rgba(148, 163, 184, 0.28);
    --subnav-cta-text: #e2e8f0;
    --subnav-cta-bg-hover: rgba(255, 255, 255, 0.06);
}

.page-subnav-target {
    scroll-margin-top: calc(
        var(--nav-offset, 72px) + var(--subnav-height, 52px) + 16px + env(safe-area-inset-top, 0px)
    );
}

.page-subnav {
    position: fixed;
    left: 0;
    right: 0;
    top: var(--subnav-stack-top);
    z-index: 900;
    width: 100vw;
    max-width: 100%;
    height: auto;
    box-sizing: border-box;
    border-bottom: 1px solid var(--subnav-border);
    background: var(--subnav-bg);
    box-shadow: var(--subnav-shadow);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    opacity: 0;
    transform: translateY(calc(-100% - 6px));
    pointer-events: none;
    transition:
        opacity 0.24s ease,
        transform 0.24s cubic-bezier(0.22, 1, 0.36, 1);
}

.page-subnav.is-visible {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

.page-subnav__inner {
    display: flex;
    align-items: center;
    gap: clamp(10px, 1.6vw, 18px);
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 max(var(--spacing-md), env(safe-area-inset-right, 0px))
        0 max(var(--spacing-md), env(safe-area-inset-left, 0px));
    box-sizing: border-box;
    min-height: 48px;
}

.page-subnav__label {
    flex-shrink: 0;
    font-size: 0.78rem;
    font-weight: 600;
    letter-spacing: 0.01em;
    color: var(--subnav-label);
    white-space: nowrap;
    padding-right: 10px;
    margin-right: 2px;
    border-right: 1px solid var(--subnav-border);
}

.page-subnav__list {
    display: flex;
    align-items: stretch;
    gap: 2px;
    flex: 1;
    min-width: 0;
    margin: 0;
    padding: 0;
    list-style: none;
    overflow-x: auto;
    overscroll-behavior-x: contain;
    scroll-snap-type: x proximity;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
}

.page-subnav__list::-webkit-scrollbar {
    display: none;
}

.page-subnav__list li {
    display: flex;
    align-items: stretch;
}

.page-subnav__link {
    display: inline-flex;
    align-items: center;
    flex-shrink: 0;
    scroll-snap-align: start;
    position: relative;
    padding: 14px 11px 12px;
    border-radius: 0;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--subnav-link);
    text-decoration: none;
    white-space: nowrap;
    background: transparent;
    transition: color 0.18s ease;
}

.page-subnav__link::after {
    content: '';
    position: absolute;
    left: 11px;
    right: 11px;
    bottom: 0;
    height: 2px;
    border-radius: 2px 2px 0 0;
    background: var(--subnav-indicator);
    transform: scaleX(0);
    transform-origin: center;
    transition: transform 0.2s ease;
}

.page-subnav__link:hover {
    color: var(--subnav-link-hover);
    background: transparent;
}

.page-subnav__link.is-active {
    color: var(--subnav-link-active);
    font-weight: 600;
    background: transparent;
    box-shadow: none;
}

.page-subnav__link.is-active::after {
    transform: scaleX(1);
}

.page-subnav__cta {
    flex-shrink: 0;
    padding: 6px 14px;
    font-size: 0.8125rem;
    font-weight: 600;
    line-height: 1.3;
    border-radius: 6px;
    border: 1px solid var(--subnav-cta-border);
    background: transparent;
    color: var(--subnav-cta-text);
    text-decoration: none;
    white-space: nowrap;
    transition: background 0.18s ease, border-color 0.18s ease, color 0.18s ease;
}

.page-subnav__cta:hover {
    background: var(--subnav-cta-bg-hover);
    border-color: rgba(148, 163, 184, 0.42);
    color: #f8fafc;
}

@media (prefers-reduced-motion: reduce) {
    .page-subnav,
    .page-subnav__link,
    .page-subnav__link::after,
    .page-subnav__cta {
        transition: none;
    }
}

@media (max-width: 768px) {
    .page-subnav__inner {
        min-height: 44px;
    }

    .page-subnav__label {
        display: none;
    }

    .page-subnav__link {
        padding: 12px 9px 10px;
        font-size: 0.84rem;
    }

    .page-subnav__link::after {
        left: 9px;
        right: 9px;
    }

    .page-subnav__cta {
        padding: 5px 10px;
        font-size: 0.78rem;
    }
}

@media (max-width: 480px) {
    .page-subnav__cta {
        display: none;
    }
}