/* ========================================
   Ling.AI - 导航栏组件样式
   ======================================== */

:root {
    --nav-accent: #6768b6;
    --nav-accent-strong: #4f518f;
    --nav-accent-soft: rgba(103, 104, 182, 0.12);
}

.navbar {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(248, 248, 251, 0.86);
    border-bottom: 1px solid rgba(21, 21, 27, 0.07);
    backdrop-filter: saturate(140%) blur(12px);
    -webkit-backdrop-filter: saturate(140%) blur(12px);
    transition: background 0.22s ease, border-color 0.22s ease, box-shadow 0.22s ease;
}

.navbar.scrolled {
    background: rgba(248, 248, 251, 0.94);
    border-bottom-color: rgba(21, 21, 27, 0.07);
    box-shadow: none;
}

.navbar-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem 24px;
    max-width: 1140px;
    margin: 0 auto;
    min-height: 70px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0;
    color: #15151b;
    text-decoration: none;
    transition: opacity 0.2s ease;
}

.logo:hover { opacity: 0.8; }

.logo-svg {
    width: 160px;
    height: 70px;
    display: block;
    flex-shrink: 0;
    color: #15151b;
}

.nav-links { display: flex; gap: 36px; }

.nav-link {
    font-size: 14px;
    font-weight: 500;
    color: #575866;
    text-transform: none;
    letter-spacing: 0.02em;
    padding: 0.25rem 0;
    position: relative;
    text-decoration: none;
    transition: color 0.2s ease;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 1.5px;
    background: linear-gradient(90deg, var(--nav-accent), #8e8f9d);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.3s ease;
}

.nav-link:hover, .nav-link.active { color: var(--nav-accent); }
.nav-link:hover::after, .nav-link.active::after { transform: scaleX(1); }

.nav-actions { display: flex; align-items: center; gap: 8px; }

.nav-language-switch {
    position: relative;
    display: inline-flex;
    align-items: center;
    margin-right: 1px;
}

.language-menu {
    position: relative;
    color: #575866;
}

.language-menu summary {
    list-style: none;
}

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

.language-menu__trigger {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    height: 36px;
    padding: 0 9px;
    border: 1px solid transparent;
    border-radius: 9px;
    background: transparent;
    color: inherit;
    cursor: pointer;
    font-size: 12.5px;
    font-weight: 600;
    line-height: 1;
    transition: color 0.18s ease, background 0.18s ease, border-color 0.18s ease;
}

.language-menu__trigger:hover,
.language-menu[open] .language-menu__trigger {
    border-color: rgba(103, 104, 182, 0.1);
    background: rgba(103, 104, 182, 0.07);
    color: var(--nav-accent-strong);
}

.language-menu__trigger:focus-visible {
    outline: 2px solid var(--nav-accent);
    outline-offset: 2px;
}

.language-menu__globe {
    width: 15px;
    height: 15px;
    opacity: 0.72;
}

.language-menu__current {
    min-width: 24px;
    text-align: center;
}

.language-menu__chevron {
    width: 11px;
    height: 11px;
    opacity: 0.52;
    transition: transform 0.18s ease;
}

.language-menu[open] .language-menu__chevron {
    transform: rotate(180deg);
}

.language-menu__popover {
    position: absolute;
    z-index: 1100;
    top: calc(100% + 9px);
    right: 0;
    display: grid;
    gap: 3px;
    width: 148px;
    padding: 6px;
    border: 1px solid rgba(21, 21, 27, 0.09);
    border-radius: 12px;
    background: rgba(255, 255, 255, 0.96);
    box-shadow: 0 16px 40px rgba(21, 21, 27, 0.13);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    transform-origin: top right;
    animation: languageMenuReveal 0.16s ease-out;
}

.language-menu__option {
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: 36px;
    padding: 0 10px;
    border-radius: 8px;
    color: #575866;
    font-size: 13px;
    font-weight: 550;
    text-decoration: none;
    transition: color 0.16s ease, background 0.16s ease;
}

.language-menu__option:hover {
    background: rgba(21, 21, 27, 0.04);
    color: #15151b;
}

.language-menu__option.is-active {
    background: var(--nav-accent-soft);
    color: var(--nav-accent-strong);
    font-weight: 650;
}

.language-menu__option svg {
    width: 14px;
    height: 14px;
    opacity: 0;
}

.language-menu__option.is-active svg {
    opacity: 1;
}

.language-menu.is-switching {
    opacity: 0.64;
    pointer-events: none;
}

@keyframes languageMenuReveal {
    from { opacity: 0; transform: translateY(-4px) scale(0.98); }
    to { opacity: 1; transform: translateY(0) scale(1); }
}

.nav-icon {
    color: #575866;
    transition: color 0.2s ease, transform 0.2s ease;
    display: flex;
    align-items: center;
}

.nav-icon svg { width: 22px; height: 22px; fill: currentColor; }
.nav-icon:hover { color: var(--nav-accent); transform: translateY(-2px); }

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 9px 18px;
    font-size: 14px;
    font-weight: 600;
    border-radius: 8px;
    cursor: pointer;
    white-space: nowrap;
    text-decoration: none;
    letter-spacing: 0.01em;
    transition: background 0.18s ease, border-color 0.18s ease, color 0.18s ease, transform 0.18s ease;
}

.btn-primary {
    background: linear-gradient(135deg, #15151b, #292a3f);
    border: 1px solid #15151b;
    color: #fafafa;
    box-shadow: none;
}

.btn-primary:hover {
    background: #292a3f;
    border-color: #292a3f;
    color: #fafafa;
    box-shadow: none;
    transform: translateY(-1px);
}

.btn-secondary {
    background: #ffffff;
    border: 1px solid rgba(21, 21, 27, 0.12);
    color: #15151b;
}

.btn-secondary:hover {
    border-color: var(--nav-accent);
    color: var(--nav-accent);
    background: #ffffff;
}

.hamburger {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.25rem;
    position: relative;
}

.hamburger span, .hamburger span::before, .hamburger span::after {
    display: block;
    width: 24px;
    height: 2px;
    background: #15151b;
    border-radius: 2px;
    transition: all 0.3s ease;
}

.hamburger span::before { content: ''; position: relative; top: -8px; }
.hamburger span::after { content: ''; position: relative; top: 8px; }
.hamburger[aria-expanded="true"] span { background: transparent; }
.hamburger[aria-expanded="true"] span::before { top: 0; transform: rotate(45deg); }
.hamburger[aria-expanded="true"] span::after { top: 0; transform: rotate(-45deg); }

.mobile-menu {
    position: fixed;
    inset: 0;
    background: #f8f8fb;
    z-index: 1001;
    transform: translateX(100%);
    transition: transform 0.4s ease;
    display: none;
}

.mobile-menu.active { transform: translateX(0); }

.mobile-menu-content {
    padding: 2rem;
    height: 100%;
    display: flex;
    flex-direction: column;
}

.mobile-menu-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: 2rem;
    border-bottom: 1px solid rgba(21, 21, 27, 0.07);
}

.mobile-menu-close {
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    color: #15151b;
}

.mobile-menu-close svg { width: 24px; height: 24px; }

.mobile-nav-links {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    padding: 2rem 0;
    flex: 1;
}

.mobile-nav-link {
    font-size: 1.125rem;
    font-weight: 500;
    color: #575866;
    padding: 1rem 0;
    text-decoration: none;
    border-bottom: 1px solid rgba(21, 21, 27, 0.07);
    transition: color 0.2s ease;
}

.mobile-nav-link:hover, .mobile-nav-link.active { color: var(--nav-accent); }

.mobile-menu-actions {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    padding-top: 2rem;
    border-top: 1px solid rgba(21, 21, 27, 0.07);
}

.mobile-language-preference {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    padding: 0.7rem 0.75rem;
    border: 1px solid rgba(21, 21, 27, 0.07);
    border-radius: 12px;
    background: rgba(21, 21, 27, 0.025);
}

.mobile-language-preference__copy {
    display: flex;
    flex-direction: column;
    gap: 0.12rem;
    color: #15151b;
    font-size: 0.875rem;
    font-weight: 650;
}

.mobile-language-preference__copy small {
    color: #7b7c89;
    font-size: 0.72rem;
    font-weight: 500;
}

@media (max-width: 1024px) { .nav-links { gap: 1.5rem; } }

@media (max-width: 900px) {
    .navbar-container {
        padding: 0.75rem 1.5rem;
        min-height: 0;
    }

    .logo-svg {
        width: 112px;
        height: 49px;
    }
    .nav-links { display: none; }
    .nav-actions { display: none; }
    .hamburger { display: block; }
    /* 为什么这样改：关闭状态的移动菜单若停在视口外，会被浏览器计入横向宽度导致移动端页面溢出。 */
    /* 错误改回 display:block 会让包含顶部导航的页面在小屏出现横向滚动。 */
    .mobile-menu { display: none; }
    .mobile-menu.active { display: block; }
}

@media (max-width: 420px) {
    .mobile-menu-content { padding: 1.25rem; }
    .mobile-language-preference {
        gap: 0.5rem;
    }
}

@media (prefers-reduced-motion: reduce) {
    .navbar,
    .nav-link::after,
    .mobile-menu,
    .language-menu__trigger,
    .language-menu__chevron,
    .language-menu__option {
        transition: none;
    }

    .language-menu__popover {
        animation: none;
    }
}