/* ============================================================
   学习中心 — Apple Light Theme
   ============================================================ */

.learning-hub {
    position: fixed;
    bottom: 80px;
    left: 50%;
    transform: translateX(-50%);
    width: 340px;
    max-width: 92vw;
    background: rgba(255, 255, 255, 0.88);
    backdrop-filter: blur(40px) saturate(180%);
    -webkit-backdrop-filter: blur(40px) saturate(180%);
    border: 1px solid rgba(0, 0, 0, 0.06);
    border-radius: 18px;
    color: #1d1d1f;
    z-index: 1500;
    animation: hubSlideUp 0.4s ease;
    overflow: hidden;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
}

@keyframes hubSlideUp {
    from { opacity: 0; transform: translateX(-50%) translateY(20px); }
    to   { opacity: 1; transform: translateX(-50%) translateY(0); }
}

/* Tab 导航栏 */
.learning-hub-tabs {
    display: flex;
    gap: 0;
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
    padding: 0 8px;
}

.learning-hub-tab {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 5px;
    padding: 10px 4px;
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    color: rgba(134, 134, 139, 0.7);
    font-size: 12px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.25s ease;
    font-family: inherit;
    position: relative;
    margin-bottom: -1px;
}

.learning-hub-tab:hover {
    color: rgba(29, 29, 31, 0.7);
}

.learning-hub-tab.active {
    color: #1d1d1f;
    border-bottom-color: var(--tab-accent, #0071e3);
}

.learning-hub-tab-icon {
    font-size: 14px;
}

.learning-hub-tab-label {
    white-space: nowrap;
}

/* 内容区 */
.learning-hub-content {
    padding: 16px 20px;
    min-height: 120px;
}

.learning-hub-panel {
    display: none;
}

/* 面板内元素统一样式 */
.learning-hub-panel .hub-item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
}

.learning-hub-panel .hub-item-label {
    font-size: 11px;
    font-weight: 600;
    color: rgba(134, 134, 139, 0.8);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.learning-hub-panel .hub-item-index {
    font-size: 11px;
    color: rgba(174, 174, 178, 0.6);
}

.learning-hub-panel .hub-item-category {
    font-size: 10px;
    padding: 2px 8px;
    border-radius: 6px;
}

.learning-hub-panel .hub-item-main {
    font-size: 26px;
    font-weight: 800;
    letter-spacing: 1px;
    margin-bottom: 6px;
    line-height: 1.3;
    color: #1d1d1f;
}

.learning-hub-panel .hub-item-sub {
    font-size: 14px;
    color: rgba(134, 134, 139, 0.9);
    margin-bottom: 4px;
}

.learning-hub-panel .hub-item-desc {
    font-size: 14px;
    color: rgba(29, 29, 31, 0.75);
    margin-bottom: 4px;
}

.learning-hub-panel .hub-item-quote {
    font-size: 12px;
    color: rgba(134, 134, 139, 0.7);
    font-style: italic;
    margin-bottom: 4px;
}

.learning-hub-panel .hub-item-trans {
    font-size: 13px;
    color: rgba(29, 29, 31, 0.65);
    margin-bottom: 12px;
}

.learning-hub-panel .hub-item-action {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.learning-hub-panel .hub-item-btn {
    padding: 7px 18px;
    border: 1px solid rgba(0, 0, 0, 0.1);
    border-radius: 10px;
    background: rgba(0, 0, 0, 0.04);
    color: #1d1d1f;
    font-size: 12px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    font-family: inherit;
}

.learning-hub-panel .hub-item-btn:hover {
    background: rgba(0, 0, 0, 0.08);
    border-color: rgba(0, 0, 0, 0.15);
}

.learning-hub-panel .hub-item-btn:active {
    transform: scale(0.96);
}

/* 响应式 */
@media (max-width: 480px) {
    .learning-hub {
        bottom: 60px;
        width: 300px;
    }
    .learning-hub-content {
        padding: 12px 16px;
    }
    .learning-hub-panel .hub-item-main {
        font-size: 22px;
    }
}

/* 仅一个 Tab 时隐藏导航栏 */
.learning-hub.single-tab .learning-hub-tabs {
    display: none;
}