@media (max-width: 900px) {
    .desktop-unified-topbar > .topbar-inner {
        width: 100%;
        min-width: 0;
        display: grid;
        grid-template-columns: auto minmax(0, 1fr);
        align-items: center;
    }

    .desktop-unified-topbar .topbar-actions {
        min-width: 0;
        justify-self: end;
    }

    .pricing-topbar {
        display: none;
    }

    body.lesson-apple-ui .topbar.desktop-unified-topbar {
        width: 100%;
        height: auto;
        min-height: 60px;
        padding: 0;
        display: block;
    }

    body.lesson-apple-ui .desktop-unified-topbar > .topbar-inner {
        width: 100%;
        height: auto;
        min-height: 60px;
        padding: 8px 14px;
        grid-template-columns: auto minmax(0, 1fr);
        align-items: center;
        gap: 8px 14px;
        box-sizing: border-box;
    }

    body.lesson-apple-ui .topbar .topbar-actions {
        width: auto;
        min-width: 0;
        display: grid;
        grid-template-columns: auto auto auto;
        align-items: center;
        justify-content: end;
        gap: 8px;
    }

    body.lesson-apple-ui .topbar .topbar-links,
    body.lesson-apple-ui .topbar .auth-status {
        min-width: 0;
    }
}

@media (max-width: 620px) {
    body.lesson-apple-ui .desktop-unified-topbar > .topbar-inner {
        grid-template-columns: minmax(0, 1fr) auto;
        grid-template-areas:
            "brand auth"
            "links version";
        gap: 7px 10px;
    }

    body.lesson-apple-ui .topbar .brand {
        grid-area: brand;
    }

    body.lesson-apple-ui .topbar .topbar-actions {
        display: contents;
    }

    body.lesson-apple-ui .topbar .topbar-links {
        grid-area: links;
        justify-self: start;
    }

    body.lesson-apple-ui .topbar .lesson-version-switcher {
        grid-area: version;
        min-width: 144px;
        height: 34px;
        justify-self: end;
    }

    body.lesson-apple-ui .topbar .auth-status {
        grid-area: auth;
        justify-self: end;
    }

    body.lesson-apple-ui .topbar .topbar-links a,
    body.lesson-apple-ui .topbar .topbar-links .topbar-profile-btn {
        padding-inline: 10px;
    }
}

.mobile-directory-brand-label,
.auth-feedback-label-short {
    display: none;
}

/* 课程页手机顶栏收成单行：目录、版本切换、账号操作。 */
@media (max-width: 620px) {
    body.lesson-apple-ui .desktop-unified-topbar > .topbar-inner {
        min-height: 52px;
        padding: 8px 12px;
        grid-template-columns: auto minmax(0, 1fr) auto auto;
        grid-template-areas: "brand spacer version auth";
        gap: 6px;
    }

    body.lesson-apple-ui .topbar .mobile-directory-brand {
        grid-area: brand;
        min-width: 0;
        min-height: 34px;
        gap: 0;
        color: #34435d;
        font-size: 13px;
        font-weight: 780;
    }

    body.lesson-apple-ui .topbar .mobile-directory-brand .brand-logo,
    body.lesson-apple-ui .topbar .mobile-directory-brand .brand-wordmark {
        display: none;
    }

    body.lesson-apple-ui .topbar .mobile-directory-brand .mobile-directory-brand-label {
        display: inline;
        white-space: nowrap;
    }

    body.lesson-apple-ui .topbar .topbar-links {
        display: none;
    }

    body.lesson-apple-ui .topbar .lesson-version-switcher {
        grid-area: version;
        width: 164px;
        min-width: 0;
        height: 32px;
        justify-self: end;
        font-size: 11px;
    }

    body.lesson-apple-ui .topbar .auth-status {
        grid-area: auth;
        min-width: 0;
        justify-self: end;
    }

    body.lesson-apple-ui .topbar .auth-account {
        gap: 5px;
    }

    body.lesson-apple-ui .topbar .auth-feedback-btn {
        min-height: 34px;
        padding: 0 9px;
        border: 0;
        background: transparent;
        box-shadow: none;
        font-size: 12px;
        font-weight: 750;
    }

    body.lesson-apple-ui .topbar .auth-feedback-label-full {
        display: none;
    }

    body.lesson-apple-ui .topbar .auth-feedback-label-short {
        display: inline;
    }

    body.lesson-apple-ui .topbar .auth-avatar-btn {
        width: 34px;
        height: 34px;
        flex-basis: 34px;
        border-radius: 11px;
        box-shadow: none;
    }
}

@media (max-width: 360px) {
    body.lesson-apple-ui .desktop-unified-topbar > .topbar-inner {
        gap: 5px;
        padding-inline: 9px;
    }

    body.lesson-apple-ui .topbar .lesson-version-switcher {
        width: 146px;
        font-size: 11px;
    }

    body.lesson-apple-ui .topbar .auth-feedback-btn {
        padding-inline: 6px;
    }
}

@media (min-width: 901px) {
    .topbar,
    .admin-topbar {
        position: sticky;
        top: 0;
        z-index: 40;
        width: 100%;
        height: 60px;
        min-height: 60px;
        padding: 0;
        border-bottom: 1px solid rgba(29, 29, 31, 0.08);
        background: rgba(251, 251, 253, 0.82);
        box-shadow: 0 1px 0 rgba(255, 255, 255, 0.78) inset;
        backdrop-filter: saturate(180%) blur(22px);
        -webkit-backdrop-filter: saturate(180%) blur(22px);
    }

    body .topbar.desktop-unified-topbar,
    body .admin-topbar.desktop-unified-topbar,
    body .pricing-topbar {
        height: 60px;
        min-height: 60px;
        padding: 0;
        display: block;
    }

    .topbar-inner,
    .admin-topbar .topbar-inner {
        width: 100%;
        max-width: none;
        height: 60px;
        margin: 0;
        padding: 0 34px;
        display: flex;
        align-items: center;
        justify-content: space-between;
        gap: 24px;
        box-sizing: border-box;
    }

    .topbar .brand,
    .admin-topbar .admin-brand {
        min-width: 0;
        display: inline-flex;
        align-items: center;
        gap: 10px;
        color: #1d1d1f;
        font-size: 18px;
        font-weight: 800;
        line-height: 1;
        text-decoration: none;
        white-space: nowrap;
    }

    .topbar .brand-logo,
    body .topbar.desktop-unified-topbar .brand-logo,
    .admin-topbar .brand-logo {
        width: 32px;
        height: 32px;
        border-radius: 9px;
        flex: 0 0 auto;
    }

    .topbar .brand .brand-wordmark,
    body .topbar.desktop-unified-topbar .brand .brand-wordmark,
    .admin-topbar .brand-wordmark {
        color: #1d1d1f;
        font-size: 21px;
        font-weight: 850;
        letter-spacing: 0;
    }

    .admin-brand-label {
        min-height: 28px;
        padding: 0 11px;
        border: 1px solid rgba(29, 29, 31, 0.1);
        border-radius: 999px;
        background: rgba(255, 255, 255, 0.72);
        color: #6e6e73;
        display: inline-flex;
        align-items: center;
        font-size: 13px;
        font-weight: 750;
        line-height: 1;
    }

    .topbar-actions,
    .topbar-links,
    .topbar .auth,
    .topbar .auth-status,
    .admin-topbar .auth-status,
    .admin-topbar .auth {
        display: flex;
        align-items: center;
        justify-content: flex-end;
        gap: 10px;
        min-width: 0;
        flex-wrap: nowrap;
    }

    .topbar-actions {
        margin-left: auto;
    }

    .topbar .auth-account,
    .admin-topbar .auth-account {
        display: flex;
        align-items: center;
        gap: 10px;
        flex-wrap: nowrap;
    }

    .topbar a,
    .admin-topbar a {
        text-decoration: none;
    }

    .topbar-links a,
    .topbar-actions > a,
    .topbar-profile-btn,
    .topbar .btn,
    .topbar .auth-link-button,
    .topbar .auth-pill-button,
    .topbar .auth-feedback-btn,
    .topbar .auth-loading-pill,
    .admin-topbar .auth-link-button,
    .admin-topbar .auth-pill-button,
    .admin-topbar .auth-feedback-btn,
    .admin-topbar .auth-loading-pill {
        min-height: 38px;
        padding: 0 15px;
        border: 1px solid rgba(29, 29, 31, 0.1);
        border-radius: 999px;
        background: rgba(255, 255, 255, 0.68);
        color: #1d1d1f;
        box-shadow: 0 8px 22px rgba(15, 23, 42, 0.045);
        display: inline-flex;
        align-items: center;
        justify-content: center;
        font: inherit;
        font-size: 14px;
        font-weight: 650;
        line-height: 1;
        letter-spacing: 0;
        white-space: nowrap;
        cursor: pointer;
        transition:
            transform 0.18s cubic-bezier(0.2, 0.72, 0.24, 1),
            box-shadow 0.18s ease,
            background 0.18s ease,
            border-color 0.18s ease,
            color 0.18s ease;
    }

    .topbar .auth-pill-button,
    .topbar .btn-register,
    .admin-topbar .auth-pill-button {
        border-color: transparent;
        background: #0071e3;
        color: #fff;
        box-shadow: 0 12px 28px rgba(0, 113, 227, 0.18);
    }

    .topbar-links a:hover,
    .topbar-actions > a:hover,
    .topbar-profile-btn:hover,
    .topbar .btn:hover,
    .topbar .auth-link-button:hover,
    .topbar .auth-pill-button:hover,
    .topbar .auth-feedback-btn:hover,
    .admin-topbar .auth-link-button:hover,
    .admin-topbar .auth-pill-button:hover,
    .admin-topbar .auth-feedback-btn:hover {
        transform: translateY(-1px);
        border-color: rgba(0, 113, 227, 0.18);
        background: rgba(255, 255, 255, 0.92);
        color: #0071e3;
        box-shadow: 0 12px 28px rgba(15, 23, 42, 0.07);
    }

    .topbar .auth-pill-button:hover,
    .topbar .btn-register:hover,
    .admin-topbar .auth-pill-button:hover {
        background: #0077ed;
        color: #fff;
        box-shadow: 0 14px 30px rgba(0, 113, 227, 0.2);
    }

    .topbar .auth-avatar-btn,
    .admin-topbar .auth-avatar-btn {
        width: 40px;
        height: 40px;
        border: 1px solid rgba(29, 29, 31, 0.1);
        border-radius: 50%;
        background: rgba(255, 255, 255, 0.74);
        box-shadow: 0 8px 22px rgba(15, 23, 42, 0.055);
    }

    .topbar .auth-avatar-btn:hover,
    .admin-topbar .auth-avatar-btn:hover {
        transform: translateY(-1px);
        box-shadow: 0 12px 28px rgba(15, 23, 42, 0.08);
    }

    .pricing-topbar {
        display: block;
    }

    .pricing-close {
        top: 76px;
        right: max(24px, calc((100vw - 1080px) / 2));
        width: 36px;
        height: 36px;
        display: grid;
        border-color: rgba(29, 29, 31, 0.08);
        background: rgba(255, 255, 255, 0.88);
    }

    .pricing-topbar + .membership-pricing-page {
        min-height: calc(100vh - 60px);
        padding-top: 42px;
    }
}