/* 导航系统 */
.navbar {
    height: 54px;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    position: fixed;
    top: 0; width: 100%; z-index: 1000;
    background: var(--nav-bg);
    font-family: var(--font-main);
    transition: background 0.3s;
}

.navbar-inner {
    width: 100%;
    max-width: 1120px;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-left {
    display: flex;
    align-items: center;
    gap: 32px;
}

.logo {
    font-weight: 700; 
    font-size: 16px;
    text-decoration: none; 
    color: var(--text-color);
    white-space: nowrap;
    letter-spacing: -0.01em;
}

.nav-links { display: flex; gap: 24px; align-items: center; }

.nav-links a {
    text-decoration: none;
}

.nav-item { 
    font-size: 13px; 
    font-weight: 400; 
    color: var(--text-color); 
    cursor: pointer; 
    transition: opacity 0.15s ease, color 0.15s ease; 
    opacity: 1;
    text-decoration: none;
}

.nav-links:hover .nav-item,
.nav-links.has-active .nav-item {
    opacity: 0.5;
    color: var(--secondary-text);
    transition: all 0.2s ease;
}

.nav-links .nav-item:hover,
.nav-links .nav-item.active,
.nav-links .nav-item.current-page { 
    opacity: 1 !important; 
    color: var(--text-color) !important;
    font-weight: 400;
    text-decoration: none;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 20px;
}

.search-container {
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    width: 18px;
    height: 18px;
    flex-shrink: 0;
    margin: 0;
    padding: 0;
}

.search-icon {
    color: var(--text-color);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: opacity 0.2s, transform 0.3s cubic-bezier(0.68, -0.55, 0.265, 1.55);
    position: relative;
    width: 18px;
    height: 18px;
}

.search-icon:hover {
    opacity: 0.7;
}

.search-icon .icon-search,
.search-icon .icon-close {
    transition: opacity 0.15s ease, transform 0.2s ease;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 18px;
    height: 18px;
}

.search-icon .icon-close {
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.5);
}

.search-icon.active .icon-search {
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.5);
}

.search-icon.active .icon-close {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
}

.search-container--mobile {
    display: none;
}

/* Full Screen Search Overlay - OpenAI Style */
.search-overlay {
    position: fixed;
    top: 54px;
    left: 0;
    width: 100%;
    height: calc(100% - 54px);
    background: var(--bg-color);
    z-index: 999;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
    display: flex;
    flex-direction: column;
}

.search-overlay.active {
    opacity: 1;
    visibility: visible;
}

.search-overlay.active .search-overlay-input-wrapper {
    animation: slideDown 0.3s ease forwards;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.search-overlay-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    padding-top: 9vh;
    max-width: 860px;
    margin: 0 auto;
    width: 100%;
    padding-left: 24px;
    padding-right: 24px;
    overflow: hidden;
}

.search-overlay-input-wrapper {
    width: 100%;
    position: relative;
}

.search-overlay-input {
    width: 100%;
    background: transparent;
    border: none;
    border-bottom: 1px solid var(--border-light);
    color: var(--text-color);
    font-size: 32px;
    font-weight: 400;
    outline: none;
    padding: 16px 48px 16px 0;
    transition: border-color 0.3s ease;
}

.search-overlay-input::placeholder {
    color: var(--secondary-text);
    opacity: 0.6;
}

.search-overlay-input:focus {
    border-bottom-color: var(--text-color);
}

.search-overlay-submit {
    position: absolute;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    background: var(--text-color);
    border: none;
    color: var(--bg-color);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: opacity 0.2s, transform 0.2s;
}

.search-overlay-submit:hover {
    opacity: 0.8;
    transform: translateY(-50%) scale(1.05);
}

.search-results {
    width: 100%;
    margin-top: 18px;
    display: flex;
    flex-direction: column;
    gap: 0;
}

.search-results-desktop {
    flex: 1;
    min-height: 0;
    overflow-y: auto;
    padding-bottom: 24px;
}

.search-count {
    font-size: 12px;
    color: var(--secondary-text);
    letter-spacing: 0.02em;
    padding: 2px 2px 6px;
}

.search-state {
    font-size: 14px;
    color: var(--secondary-text);
    padding: 16px 0;
    border-bottom: 1px solid var(--border-light);
}

.search-result-item {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 128px;
    align-items: center;
    gap: 24px;
    border: none;
    border-bottom: 1px solid var(--border-light);
    border-radius: 0;
    padding: 18px 0;
    text-decoration: none;
    color: var(--text-color);
    background: transparent;
    transition: opacity 0.14s ease;
}

.search-result-item:hover {
    opacity: 0.86;
}

.search-result-item:first-child {
    border-top: 1px solid var(--border-light);
}

.search-result-thumb {
    width: 128px;
    height: 128px;
    border-radius: 6px;
    overflow: hidden;
    flex-shrink: 0;
    background: var(--bg-section);
    justify-self: end;
}

.search-result-thumb img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.search-result-body {
    min-width: 0;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.search-result-title {
    font-size: 30px;
    font-weight: 600;
    line-height: 1.14;
    letter-spacing: -0.01em;
    margin: 0;
    color: var(--text-color);
    display: -webkit-box;
    line-clamp: 2;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.search-result-meta {
    margin: 0;
    font-size: 13px;
    font-weight: 500;
    color: var(--secondary-text);
    line-height: 1.25;
}

.search-result-excerpt {
    margin: 0;
    font-size: 16px;
    color: var(--secondary-text);
    line-height: 1.3;
    display: -webkit-box;
    line-clamp: 3;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

/* Responsive adjustments for search overlay */
@media (max-width: 768px) {
    .search-overlay-input {
        font-size: 24px;
    }
    
    .search-overlay-content {
        padding-top: 10vh;
    }

    .search-result-item {
        grid-template-columns: minmax(0, 1fr) 84px;
        gap: 12px;
        padding: 12px 0;
    }

    .search-result-thumb {
        width: 84px;
        height: 84px;
    }

    .search-result-meta {
        font-size: 12px;
    }

    .search-result-title {
        font-size: 16px;
        line-height: 1.3;
    }

    .search-result-excerpt {
        font-size: 13px;
        line-height: 1.35;
        line-clamp: 2;
        -webkit-line-clamp: 2;
    }
}

.login-btn {
    font-size: 13px;
    font-weight: 500;
    color: var(--text-color);
    cursor: pointer;
}

.btn-pill {
    background: transparent;
    color: var(--text-color); 
    padding: 6px 12px;
    border-radius: 999px; 
    text-decoration: none; 
    font-size: 13px; 
    font-weight: 500;
    border: 1px solid var(--border-light);
    transition: all 0.2s ease;
}

.btn-pill span {
    position: relative;
    top: 0;
}

.btn-pill:hover, .btn-pill.active {
    background: var(--text-color);
    color: var(--bg-color);
    border-color: var(--text-color);
}

/* Mega Menu */
.mega-menu-container {
    position: fixed;
    top: 50px;
    left: 0;
    width: 100%;
    background-color: var(--nav-bg);
    z-index: 999;
    display: grid;
    grid-template-rows: 0fr;
    overflow: hidden;
    transition: grid-template-rows 0.12s ease-out,
                visibility 0.12s, background-color 0.2s;
    visibility: hidden;
    box-sizing: border-box;
}

.menu-line {
    height: 1px;
    background: var(--border-light);
    margin: 0 auto;
    width: 0;
    opacity: 0;
    transition: width 0.25s cubic-bezier(0.19, 1, 0.22, 1),
                opacity 0.15s ease-out;
}

.mega-menu-container.active .menu-line {
    opacity: 1;
}

.mega-menu-inner {
    min-height: 0;
    padding: 0 40px;
    opacity: 0;
    transition: opacity 0.1s ease-out,
                height 0.18s cubic-bezier(0.19, 1, 0.22, 1),
                padding 0.18s cubic-bezier(0.19, 1, 0.22, 1);
    overflow: hidden;
}

.mega-menu-container.active {
    grid-template-rows: 1fr;
    visibility: visible;
}

.mega-menu-container.active .mega-menu-inner {
    opacity: 1;
    padding-top: 30px;
    padding-bottom: 40px;
}

.menu-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--overlay-bg);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.5s cubic-bezier(0.19, 1, 0.22, 1),
                visibility 0.5s cubic-bezier(0.19, 1, 0.22, 1);
    z-index: 998;
    pointer-events: none;
}

.menu-overlay.active {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

.menu-content-wrapper {
    max-width: 1440px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(12, 1fr);
    gap: 24px;
    padding: 24px 24px 48px 24px;
    transition: opacity 80ms ease-in-out;
    opacity: 1;
    width: 100%;
}

.menu-column a {
    color: var(--text-color);
    text-decoration: none;
    display: block;
    font-size: 15px;
    font-weight: 600;
    transition: color 0.2s, opacity 0.2s;
    line-height: 1.5;
}

/* Secondary links hover effect */
.menu-column.latest-updates a:hover {
    opacity: 0.7;
    text-decoration: none;
}

/* Main links (Left Column) */
.menu-column.main-links {
    grid-column: 1 / span 6; /* Align to far left (col 1) */
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.menu-column.main-links a {
    font-size: 32px;
    font-weight: 600;
    letter-spacing: -0.02em;
    color: var(--text-color);
    line-height: 1.1;
    margin-bottom: 0;
    width: fit-content;
}

.menu-column.main-links a:hover {
    opacity: 0.7;
}

/* Secondary links container (Right Column) */
.menu-column.latest-updates {
    grid-column: 7 / span 5; /* Shift left slightly to balance */
    display: flex;
    flex-direction: column;
    gap: 8px;
    padding-top: 6px; /* Visual alignment with main links */
}

.menu-column .label {
    font-size: 13px;
    font-weight: 500;
    color: var(--secondary-text);
    display: block;
    margin-bottom: 16px;
}
/* When hovering the wrapper, dim ALL links */
.menu-content-wrapper:hover a {
    opacity: 0.4;
    color: var(--secondary-text);
}

/* But keep the hovered link bright */
.menu-content-wrapper a:hover {
    opacity: 1 !important;
    color: var(--text-color) !important;
    text-decoration: none; /* Remove underline */
}

/* Responsive adjustments for Tablet/Smaller Desktop */
@media (max-width: 1024px) {
    .menu-column.main-links a {
        font-size: 28px;
    }
}

/* 响应式断点 */
@media (max-width: 910px) {
    .nav-links { display: none; }
    .nav-right .login-btn, .nav-right .btn-pill { display: none; }
    .nav-right { gap: 10px; }
    .search-container--nav { display: none; }
    .search-container--mobile { display: flex; }
    .nav-right .search-container {
        width: auto;
        height: auto;
    }
    .nav-right .search-icon {
        display: flex;
        width: 34px;
        height: 34px;
        border: 1px solid var(--border-light);
        border-radius: 999px;
        transition: background-color 0.15s ease, border-color 0.15s ease;
    }
    .nav-right .search-icon:hover {
        opacity: 1;
        background: var(--bg-card);
    }
    .mega-menu-container { display: none !important; }
    
    /* Hide desktop search input on narrow screens */
    .search-container .search-input { display: none; }
    .search-container.active .search-input { display: none; }
}