:root {
    --topnav-height: 48px;
}

body.is-learning-page.has-topnav {
    padding-top: var(--topnav-height);
}

body.is-learning-page #appContent {
    min-height: calc(100vh - var(--topnav-height));
}

.has-topnav {
    padding-top: 0;
}

#appContent {
    min-height: calc(100vh - var(--topnav-height));
}

.site-topnav {
    position: relative;
    top: auto;
    left: auto;
    right: auto;
    z-index: 4;
    height: var(--topnav-height);
    border-bottom: 1px solid transparent;
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    background: rgba(255, 255, 255, 0.92);
    transition:
        background-color 0.25s ease,
        backdrop-filter 0.25s ease,
        -webkit-backdrop-filter 0.25s ease,
        border-color 0.25s ease;
}

body.is-learning-page .site-topnav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
}

.dark .site-topnav {
    background: rgba(22, 22, 23, 0.82);
}

.site-topnav-bar {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

.site-topnav-logo {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    flex-shrink: 0;
    text-decoration: none;
    color: inherit;
}

.site-topnav-logo-mark {
    display: block;
    width: 24px;
    height: 24px;
    flex-shrink: 0;
    object-fit: contain;
}

.site-topnav-wordmark {
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.02em;
    color: #1d1d1f;
    white-space: nowrap;
}

.site-topnav-wordmark-en {
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.02em;
    color: #1d1d1f;
}

.dark .site-topnav-wordmark {
    color: #f5f5f7;
}

.dark .site-topnav-wordmark-en {
    color: #f5f5f7;
}

.site-topnav-links {
    display: none;
    align-items: center;
    justify-content: center;
    gap: 1.75rem;
    flex: 1;
    min-width: 0;
}

@media (min-width: 768px) {
    .site-topnav-links {
        display: flex;
    }
}

.site-topnav-link {
    font-size: 12px;
    line-height: 1;
    font-weight: 400;
    letter-spacing: -0.01em;
    color: rgba(29, 29, 31, 0.88);
    text-decoration: none;
    background: none;
    border: 0;
    padding: 0;
    cursor: pointer;
    white-space: nowrap;
}

.dark .site-topnav-link {
    color: rgba(245, 245, 247, 0.88);
}

.site-topnav-link.is-active {
    color: #1d1d1f;
    font-weight: 500;
}

.site-topnav-link:hover {
    font-weight: 500;
}

.dark .site-topnav-link.is-active {
    color: #f5f5f7;
}

.site-topnav-actions {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    flex-shrink: 0;
}

.site-topnav-icon-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.625rem;
    height: 1.625rem;
    border: 0;
    border-radius: 9999px;
    background: transparent;
    color: rgba(29, 29, 31, 0.8);
    text-decoration: none;
    cursor: pointer;
    transition: background-color 0.15s ease;
}

.site-topnav-icon-btn:hover {
    background: rgba(0, 0, 0, 0.06);
}

.dark .site-topnav-icon-btn {
    color: rgba(245, 245, 247, 0.8);
}

.dark .site-topnav-icon-btn:hover {
    background: rgba(255, 255, 255, 0.08);
}

.site-topnav-auth-actions {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    flex-shrink: 0;
}

@media (min-width: 768px) {
    .site-topnav-auth-actions {
        gap: 0.5rem;
    }
}

.site-topnav-install-app {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 11px;
    font-weight: 600;
    line-height: 1;
    color: var(--site-theme-color, #0071e3);
    text-decoration: none;
    padding: 0.3125rem 0.625rem;
    border: 1px solid var(--site-theme-color, #0071e3);
    border-radius: 12px;
    background: transparent;
    white-space: nowrap;
    cursor: pointer;
    transition:
        background-color 0.15s ease,
        color 0.15s ease,
        border-color 0.15s ease;
}

.site-topnav-install-app:hover {
    background: rgba(var(--site-theme-color-rgb, 0, 113, 227), 0.08);
    color: var(--site-theme-color-hover, #0b52c8);
    border-color: var(--site-theme-color-hover, #0b52c8);
}

.dark .site-topnav-install-app {
    color: var(--site-theme-color, #0071e3);
    border-color: var(--site-theme-color, #0071e3);
}

.dark .site-topnav-install-app:hover {
    background: rgba(var(--site-theme-color-rgb, 0, 113, 227), 0.14);
    color: var(--site-theme-color-hover, #0b52c8);
    border-color: var(--site-theme-color-hover, #0b52c8);
}

@media (min-width: 768px) {
    .site-topnav-install-app {
        font-size: 12px;
        padding: 0.375rem 0.75rem;
    }
}

/* macOS 14 以下 Safari：引导改用 Chrome 安装 */
.vk-pwa-mac-tip[hidden] {
    display: none !important;
}

.vk-pwa-mac-tip {
    position: fixed;
    inset: 0;
    z-index: 8;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1.25rem;
}

.vk-pwa-mac-tip__backdrop {
    position: absolute;
    inset: 0;
    background: rgba(15, 23, 42, 0.45);
}

.vk-pwa-mac-tip__panel {
    position: relative;
    width: min(100%, 22rem);
    padding: 1.5rem 1.25rem 1.25rem;
    border-radius: 16px;
    background: #fff;
    box-shadow: 0 18px 48px rgba(15, 23, 42, 0.18);
    text-align: center;
}

.vk-pwa-mac-tip__close {
    position: absolute;
    top: 0.5rem;
    right: 0.65rem;
    border: 0;
    background: transparent;
    color: #64748b;
    font-size: 1.5rem;
    line-height: 1;
    cursor: pointer;
    padding: 0.25rem;
}

.vk-pwa-mac-tip__icon {
    width: 3.5rem;
    height: 3.5rem;
    margin: 0 auto 0.85rem;
    border-radius: 12px;
    overflow: hidden;
}

.vk-pwa-mac-tip__icon img {
    display: block;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.vk-pwa-mac-tip__title {
    margin: 0 0 0.65rem;
    font-size: 1.05rem;
    font-weight: 700;
    color: #0f172a;
    line-height: 1.35;
}

.vk-pwa-mac-tip__body {
    margin: 0 0 0.5rem;
    font-size: 0.9rem;
    line-height: 1.55;
    color: #475569;
}

.vk-pwa-mac-tip__body strong {
    color: #0f172a;
    font-weight: 700;
}

.vk-pwa-mac-tip__btn {
    margin-top: 0.85rem;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 7.5rem;
    padding: 0.55rem 1.1rem;
    border: 0;
    border-radius: 12px;
    background: var(--site-theme-color, #0071e3);
    color: #fff;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
}

.vk-pwa-mac-tip__btn:hover {
    background: var(--site-theme-color-hover, #0b52c8);
}

html.vk-pwa-mac-tip-open,
html.vk-pwa-mac-tip-open body {
    overflow: hidden;
}

.site-topnav-cta {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 11px;
    font-weight: 600;
    line-height: 1;
    color: #fff;
    text-decoration: none;
    padding: 0.375rem 0.75rem;
    border-radius: 9999px;
    background: var(--site-theme-color, #0071e3);
    white-space: nowrap;
    transition: background-color 0.15s ease;
}

.site-topnav-cta:hover {
    background: var(--site-theme-color-hover, #0b52c8);
}

@media (min-width: 768px) {
    .site-topnav-cta {
        font-size: 12px;
        padding: 0.4375rem 0.875rem;
    }
}

.site-topnav-profile {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.625rem;
    height: 1.625rem;
    border: 0;
    border-radius: 9999px;
    background: transparent;
    padding: 0;
    cursor: pointer;
    text-decoration: none;
    color: inherit;
    transition: background-color 0.15s ease;
}

.site-topnav-profile:hover {
    background: rgba(0, 0, 0, 0.06);
}

.dark .site-topnav-profile:hover {
    background: rgba(255, 255, 255, 0.08);
}

.site-topnav-avatar {
    width: 1.625rem;
    height: 1.625rem;
    border-radius: 9999px;
    object-fit: cover;
}

.site-topnav-avatar-fallback {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.06);
    color: rgba(29, 29, 31, 0.65);
    font-size: 0.875rem;
}

.dark .site-topnav-avatar-fallback {
    background: rgba(255, 255, 255, 0.1);
    color: rgba(245, 245, 247, 0.65);
}

.site-topnav-menu-btn {
    display: inline-flex;
}

@media (min-width: 768px) {
    .site-topnav-menu-btn {
        display: none;
    }
}

.topnav-menu-icon-close {
    display: none;
}

body.topnav-menu-open .topnav-menu-icon-open {
    display: none;
}

body.topnav-menu-open .topnav-menu-icon-close {
    display: inline-flex;
}

.site-topnav-mobile {
    position: fixed;
    inset: 0;
    z-index: 50;
    overflow-x: hidden;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity 0.32s cubic-bezier(0.22, 1, 0.36, 1), visibility 0.32s cubic-bezier(0.22, 1, 0.36, 1);
    background: #ffffff;
}

.dark .site-topnav-mobile {
    background: #000000;
}

.site-topnav-mobile.is-open {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

.site-topnav-mobile-nav {
    min-height: 100%;
    padding-top: calc(var(--topnav-height) + 2rem);
    padding-bottom: 2.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.site-topnav-mobile-nav > * {
    opacity: 0;
    transform: translateY(1.5rem);
}

.site-topnav-mobile:not(.is-open) .site-topnav-mobile-nav > * {
    animation: none;
}

.site-topnav-mobile.is-open .site-topnav-mobile-nav > * {
    animation: topnavMobileItemIn 0.52s cubic-bezier(0.22, 1, 0.36, 1) forwards;
}

.site-topnav-mobile.is-open .site-topnav-mobile-nav > *:nth-child(1) { animation-delay: 0.06s; }
.site-topnav-mobile.is-open .site-topnav-mobile-nav > *:nth-child(2) { animation-delay: 0.12s; }
.site-topnav-mobile.is-open .site-topnav-mobile-nav > *:nth-child(3) { animation-delay: 0.18s; }
.site-topnav-mobile.is-open .site-topnav-mobile-nav > *:nth-child(4) { animation-delay: 0.24s; }
.site-topnav-mobile.is-open .site-topnav-mobile-nav > *:nth-child(5) { animation-delay: 0.30s; }
.site-topnav-mobile.is-open .site-topnav-mobile-nav > *:nth-child(6) { animation-delay: 0.36s; }
.site-topnav-mobile.is-open .site-topnav-mobile-nav > *:nth-child(7) { animation-delay: 0.42s; }
.site-topnav-mobile.is-open .site-topnav-mobile-nav > *:nth-child(8) { animation-delay: 0.48s; }

@keyframes topnavMobileItemIn {
    from {
        opacity: 0;
        transform: translateY(1.5rem);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.site-topnav-mobile-nav a,
.site-topnav-mobile-nav button {
    display: flex;
    align-items: center;
    width: 100%;
    padding: 0.875rem 0.25rem;
    font-size: 1.75rem;
    line-height: 1.1;
    font-weight: 600;
    letter-spacing: -0.02em;
    color: #1d1d1f;
    text-decoration: none;
    background: none;
    border: 0;
    text-align: left;
    cursor: pointer;
}

.dark .site-topnav-mobile-nav a,
.dark .site-topnav-mobile-nav button {
    color: #f5f5f7;
}

.site-topnav-mobile-group-label {
    margin-top: 0.6rem;
    padding: 0.85rem 0.25rem 0.1rem;
    border-top: 1px solid rgba(var(--site-theme-color-rgb, 0, 122, 255), 0.18);
    font-size: 0.76rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    color: var(--site-muted, #86868b);
}

.dark .site-topnav-mobile-group-label {
    border-top-color: rgba(255, 255, 255, 0.14);
}

.site-topnav-mobile-close {
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
    z-index: 2;
    width: 2.5rem;
    height: 2.5rem;
    border-radius: 9999px;
}

.site-topnav-mobile-close:hover {
    background: rgba(0, 0, 0, 0.06);
}

.dark .site-topnav-mobile-close:hover {
    background: rgba(255, 255, 255, 0.08);
}

.site-topnav-overlay {
    position: fixed;
    inset: 0;
    z-index: 3;
    background: rgba(15, 23, 42, 0.28);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity 0.28s ease, visibility 0.28s ease;
}

body.topnav-menu-open .site-topnav-overlay {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

@media (min-width: 768px) {
    .site-topnav-overlay {
        display: none;
    }
}

body.topnav-menu-open {
    overflow: hidden;
}

body.topnav-menu-open .site-topnav {
    z-index: 5;
}

@media (min-width: 768px) {
    .site-topnav-mobile {
        display: none !important;
    }
}

.site-topnav.is-learning .site-topnav-bar {
    position: relative;
    justify-content: space-between;
}

.site-topnav.is-learning .site-topnav-actions--learning {
    display: flex;
    flex-shrink: 0;
    z-index: 3;
    gap: 0.25rem;
}

.site-topnav-learning-bar {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    gap: 0.5rem;
    flex: 1;
    min-width: 0;
}

.site-topnav-learning-start,
.site-topnav-learning-end {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    flex-shrink: 0;
    z-index: 2;
    min-width: 0;
}

.site-topnav-learning-start {
    justify-self: start;
    justify-content: flex-start;
}

.site-topnav-learning-end {
    justify-self: end;
    justify-content: flex-end;
}

.site-topnav-spell-switch {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    height: 1.625rem;
    padding: 0 0.2rem 0 0.15rem;
    border: 0;
    border-radius: 9999px;
    background: transparent;
    color: #6b7280;
    font-size: 0.75rem;
    font-weight: 600;
    line-height: 1;
    cursor: pointer;
    transition: color 0.15s ease;
    white-space: nowrap;
}

.site-topnav-spell-switch__label {
    pointer-events: none;
}

.site-topnav-spell-switch__track {
    position: relative;
    display: inline-flex;
    align-items: center;
    width: 1.75rem;
    height: 1rem;
    border-radius: 9999px;
    background: #d1d5db;
    flex-shrink: 0;
    transition: background-color 0.18s ease;
}

.site-topnav-spell-switch__thumb {
    position: absolute;
    top: 1px;
    left: 1px;
    width: 0.875rem;
    height: 0.875rem;
    border-radius: 9999px;
    background: #fff;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.18);
    transition: transform 0.18s ease;
}

.site-topnav-spell-switch.is-on {
    color: #0071e3;
    background: transparent;
}

.site-topnav-spell-switch.is-on .site-topnav-spell-switch__track {
    background: #0071e3;
}

.site-topnav-spell-switch.is-on .site-topnav-spell-switch__thumb {
    transform: translateX(0.75rem);
}

.site-topnav-spell-switch.is-off {
    color: #9ca3af;
    background: transparent;
}

.dark .site-topnav-spell-switch {
    background: transparent;
    color: #9ca3af;
}

.dark .site-topnav-spell-switch__track {
    background: #444;
}

.dark .site-topnav-spell-switch.is-on {
    color: #6eb6ff;
    background: transparent;
}

.dark .site-topnav-spell-switch.is-on .site-topnav-spell-switch__track {
    background: #0071e3;
}

.dark .site-topnav-spell-switch.is-on .site-topnav-spell-switch__thumb {
    background: #fff;
}

.site-topnav-spell-switch:active {
    transform: scale(0.98);
}

.site-topnav-learning-close {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.625rem;
    height: 1.625rem;
    flex-shrink: 0;
    border: 0;
    border-radius: 9999px;
    background: transparent;
    text-decoration: none;
    cursor: pointer;
    transition: background-color 0.15s ease;
}

.site-topnav-learning-close:hover {
    background: rgba(0, 0, 0, 0.06);
}

.dark .site-topnav-learning-close:hover {
    background: rgba(255, 255, 255, 0.08);
}

.site-topnav-learning-close-dot {
    display: block;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: #ff5f57;
    box-shadow: inset 0 0 0 0.5px rgba(0, 0, 0, 0.12);
    position: relative;
}

.site-topnav-learning-close-dot::before,
.site-topnav-learning-close-dot::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 6px;
    height: 1px;
    background: rgba(76, 0, 0, 0.55);
    border-radius: 1px;
}

.site-topnav-learning-close-dot::before {
    transform: translate(-50%, -50%) rotate(45deg);
}

.site-topnav-learning-close-dot::after {
    transform: translate(-50%, -50%) rotate(-45deg);
}

.site-topnav-learning-close:hover .site-topnav-learning-close-dot {
    background: #ff3b30;
}

.site-topnav-learning-center {
    position: static;
    left: auto;
    top: auto;
    transform: none;
    max-width: 100%;
    min-width: 0;
    z-index: 1;
    text-align: center;
    justify-self: center;
    width: 100%;
}

.site-topnav-learning-center-inner {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    max-width: 100%;
    min-width: 0;
}

.site-topnav-learning-library {
    display: block;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-weight: 600;
    font-size: 0.875rem;
    line-height: 1.2;
    min-width: 0;
    flex: 1 1 auto;
}

.site-topnav-guest-quota {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    flex: 0 0 auto;
    font-size: 0.6875rem;
    font-weight: 500;
    line-height: 1.2;
    color: #6b7280;
    white-space: nowrap;
}

.site-topnav-guest-quota-count {
    color: #374151;
    font-variant-numeric: tabular-nums;
}

.site-topnav-guest-quota-count strong {
    font-weight: 600;
}

.dark .site-topnav-guest-quota {
    color: #9ca3af;
}

.dark .site-topnav-guest-quota-count {
    color: #e5e7eb;
}

@media (max-width: 767px) {
    .site-topnav-learning-bar {
        gap: 0.35rem;
    }

    .site-topnav-spell-switch {
        padding: 0 0.15rem 0 0.1rem;
        gap: 0.28rem;
        font-size: 0.6875rem;
    }

    .site-topnav-guest-quota {
        font-size: 0.625rem;
    }

    .site-topnav-guest-quota-label {
        display: none;
    }
}

.theme-icon-moon {
    display: none;
}

html.dark .theme-icon-sun {
    display: none;
}

html.dark .theme-icon-moon {
    display: inline;
}

.site-topnav-admin-link {
    display: none;
}

@media (min-width: 1024px) {
    .site-topnav-admin-link {
        display: inline-flex;
    }
}

    /* 左右等宽，词库名相对整栏视觉居中 */
    .site-topnav-learning-center {
        max-width: min(22rem, 42vw);
    }
}