* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
}

/* ==================== 全局变量 ==================== */
:root {
    --color-upper: #2563eb;
    --color-upper-light: #60a5fa;
    --color-lower: #d97706;
    --color-lower-light: #f59e0b;
    --color-lower-dark: #92400e;
    --color-neutral: #94a3b8;
    --color-lift: #be123c;
    --color-lift-negative: #2563eb;
    --color-brand: #3182ce;
    --color-brand-dark: #1e3a5f;
    --bg-page: #f0f4f8;
    --bg-card: #ffffff;
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.06);
    --shadow-strong: 0 4px 20px rgba(0, 0, 0, 0.10);
    --radius: 10px;
    --radius-sm: 6px;
}

body {
    background: var(--bg-page);
    color: var(--text-primary);
    padding: 20px;
    min-height: 100vh;
    line-height: 1.6;
}

.page {
    max-width: 1200px;
    margin: 0 auto;
}

/* ==================== 顶部标题区 ==================== */
.page-header {
    margin-bottom: 24px;
    padding-bottom: 6px;
}

.page-header h1 {
    text-align: center;
    font-size: 31px;
    margin-bottom: 12px;
    color: var(--color-brand-dark);
    font-weight: 800;
    letter-spacing: 0.5px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

.title-icon {
    width: 28px;
    height: 28px;
    flex-shrink: 0;
    color: var(--color-brand);
    filter: drop-shadow(0 2px 4px rgba(49, 130, 206, 0.3));
}

.teaching-note {
    max-width: 680px;
    margin: 0 auto;
}

.teaching-note summary {
    cursor: pointer;
    font-size: 14px;
    color: var(--text-muted);
    padding: 4px 16px;
    user-select: none;
    transition: color 0.2s;
    list-style: none;
    text-align: center;
    text-decoration: underline;
    text-decoration-color: transparent;
    text-underline-offset: 3px;
}

.note-en {
    display: inline-block;
    font-size: 11px;
    color: var(--color-brand);
    background: rgba(49, 130, 206, 0.10);
    padding: 2px 8px;
    border-radius: 20px;
    margin-left: 4px;
    font-weight: 500;
    vertical-align: middle;
    letter-spacing: 0.3px;
}

.teaching-note summary:hover {
    color: var(--color-brand);
    text-decoration-color: var(--color-brand);
}

.summary-arrow {
    display: inline-block;
    transition: transform 0.2s;
    font-size: 10px;
    margin-right: 2px;
}

.teaching-note[open] .summary-arrow {
    transform: rotate(90deg);
}

.teaching-note[open] summary {
    margin-bottom: 6px;
}

.teaching-note p {
    font-size: 13px;
    color: var(--text-secondary);
    line-height: 1.65;
    padding: 8px 16px;
    background: #f7fafc;
    border-radius: var(--radius-sm);
    border-left: 3px solid var(--color-brand);
}

/* ==================== 主体布局（默认=移动端单栏） ==================== */
.main-layout {
    display: flex;
    flex-direction: column;
    gap: 14px;
}

/* 画布+飞机姿态 组合行 */
.canvas-row {
    display: flex;
    flex-direction: column;
    gap: 14px;
}

/* 移动端默认顺序：画布 → 飞机姿态 → 控制 → 学习面板 */
.canvas-wrapper { order: 1; }
.attitude-panel { order: 2; }
.control-sidebar { order: 3; }
.learn-panel { order: 4; }

/* 移动端默认隐藏桌面暂停按钮 */
.pause-btn { display: none; }
/* 移动端默认显示悬浮暂停 */
.pause-float { display: flex; }
.hud-mobile { display: none; }

/* ===== 画布容器 ===== */
.canvas-wrapper {
    position: relative;
    background: var(--bg-card);
    border-radius: var(--radius);
    box-shadow: var(--shadow-strong);
    padding: 10px;
}

canvas {
    display: block;
    width: 100%;
    max-width: 960px;
    height: auto;
    margin: 0 auto;
    background: #D7ECFF;
    border-radius: var(--radius-sm);
    border: 1px solid #e2e8f0;
}

/* ===== 侧边栏内 HUD 数据区 ===== */
.hud-in-sidebar {
    margin-top: 12px;
    padding: 12px 12px 4px;
    border-top: 1px solid #e2e8f0;
    display: flex;
    flex-direction: column;
}

/* ===== 移动端悬浮暂停按钮 ===== */
.pause-float {
    position: absolute;
    bottom: 42px;
    left: 18px;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    border: none;
    background: rgba(49, 130, 206, 0.92);
    color: #fff;
    cursor: pointer;
    align-items: center;
    justify-content: center;
    z-index: 6;
    box-shadow: 0 2px 10px rgba(49, 130, 206, 0.4);
    transition: transform 0.15s, background 0.2s;
}

.pause-float:active {
    transform: scale(0.92);
}

.pause-float.paused {
    background: rgba(56, 161, 105, 0.92);
    box-shadow: 0 2px 10px rgba(56, 161, 105, 0.4);
}

/* ===== 临界状态提示 ===== */
.status-alert {
    position: absolute;
    top: 16px;
    left: 50%;
    transform: translateX(-50%);
    padding: 5px 14px;
    border-radius: 16px;
    font-size: 12px;
    font-weight: 700;
    opacity: 0;
    transition: opacity 0.3s;
    z-index: 6;
    pointer-events: none;
    white-space: nowrap;
}

.status-alert.show { opacity: 1; }
.status-alert.warn-zero {
    background: rgba(255, 251, 235, 0.95);
    color: #92400e;
    border: 1px solid var(--color-lower);
}
.status-alert.warn-negative {
    background: rgba(239, 246, 255, 0.95);
    color: #1e40af;
    border: 1px solid var(--color-upper);
}
.status-alert.warn-stall {
    background: rgba(254, 242, 242, 0.95);
    color: #991b1b;
    border: 1px solid var(--color-lift);
}

/* ===== 控制区 ===== */
.control-sidebar {
    background: var(--bg-card);
    border-radius: var(--radius);
    box-shadow: var(--shadow-card);
    padding: 12px 14px;
}

/* 参数滑块容器：不再需要折叠，直接显示 */
.sliders {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

/* 滑块组 */
.slider-group {
    padding: 3px 8px;
    border-radius: var(--radius-sm);
    border: 2px solid transparent;
    background: #f7fafc;
    transition: border-color 0.25s, background 0.25s;
}

.slider-group:hover,
.slider-group.active {
    border-color: var(--color-brand);
    background: #f0f7ff;
}

.slider-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: 2px;
}

.slider-label {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-primary);
}

.slider-value {
    font-size: 16px;
    font-weight: 700;
    color: var(--color-brand);
    font-variant-numeric: tabular-nums;
}

/* 触摸友好滑块 — 大按钮易点击 */
.slider-group input[type="range"] {
    width: 100%;
    height: 8px;
    border-radius: 6px;
    background: linear-gradient(90deg, #cbd5e1 0%, #e2e8f0 100%);
    outline: none;
    -webkit-appearance: none;
    cursor: pointer;
}

.slider-group input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: linear-gradient(135deg, #60a5fa 0%, #3182ce 100%);
    cursor: grab;
    box-shadow: 0 3px 10px rgba(49, 130, 206, 0.45), 0 1px 3px rgba(0,0,0,0.15);
    border: 2px solid #fff;
    transition: transform 0.15s, box-shadow 0.15s;
    margin-top: -7px;
}

.slider-group input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.18);
    box-shadow: 0 4px 14px rgba(49, 130, 206, 0.55), 0 2px 5px rgba(0,0,0,0.18);
}

.slider-group input[type="range"]::-webkit-slider-thumb:active {
    transform: scale(1.1);
    cursor: grabbing;
    box-shadow: 0 2px 6px rgba(49, 130, 206, 0.5);
}

.slider-group input[type="range"]::-moz-range-thumb {
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: linear-gradient(135deg, #60a5fa 0%, #3182ce 100%);
    cursor: grab;
    border: 2px solid #fff;
    box-shadow: 0 3px 10px rgba(49, 130, 206, 0.45), 0 1px 3px rgba(0,0,0,0.15);
    transition: transform 0.15s, box-shadow 0.15s;
}

.slider-group input[type="range"]::-moz-range-thumb:hover {
    transform: scale(1.18);
}

.slider-group input[type="range"]::-moz-range-thumb:active {
    transform: scale(1.1);
    cursor: grabbing;
}

/* ===== 学习面板（仅内容区 + 翻页导航，索引栏已移至 control-sidebar） ===== */
.learn-panel {
    background: var(--bg-card);
    border-radius: var(--radius);
    box-shadow: var(--shadow-card);
    overflow: hidden;
    min-height: 320px;
    display: flex;
    flex-direction: column;
}

/* ===== 索引栏（嵌入 control-sidebar 内） ===== */
.learn-index {
    margin-top: 14px;
    padding-top: 12px;
    border-top: 1px solid #e2e8f0;
}

.learn-index-title {
    font-size: 13px;
    font-weight: 700;
    color: var(--text-muted);
    padding: 0 16px 10px;
    border-bottom: 1px solid #e2e8f0;
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* 类别分组 */
.learn-category {
    margin-bottom: 6px;
}

.learn-category-title {
    font-size: 12px;
    font-weight: 700;
    color: var(--color-brand);
    padding: 8px 16px 4px;
    letter-spacing: 0.5px;
    cursor: pointer;
    user-select: none;
    display: flex;
    align-items: center;
    gap: 4px;
    transition: color 0.15s;
}

.learn-category-title:hover {
    color: var(--color-brand-dark);
}

.category-arrow {
    display: inline-block;
    font-size: 10px;
    color: var(--text-muted);
    transition: transform 0.2s ease;
    width: 10px;
}

/* 收起状态：箭头旋转 + 列表隐藏 */
.learn-category.collapsed .category-arrow {
    transform: rotate(-90deg);
}

.learn-index-list {
    list-style: none;
    overflow: hidden;
    transition: max-height 0.25s ease, opacity 0.2s ease;
    max-height: 600px;
    opacity: 1;
}

.learn-category.collapsed .learn-index-list {
    max-height: 0;
    opacity: 0;
}

.learn-index-item {
    padding: 8px 16px 8px 28px;
    font-size: 13px;
    cursor: pointer;
    transition: all 0.18s;
    color: var(--text-secondary);
    border-left: 4px solid transparent;
    line-height: 1.4;
}

.learn-index-item:hover {
    background: rgba(49, 130, 206, 0.06);
    color: var(--color-brand);
    border-left-color: rgba(49, 130, 206, 0.3);
}

.learn-index-item.active {
    background: rgba(49, 130, 206, 0.12);
    color: var(--color-brand-dark);
    font-weight: 600;
    border-left-color: var(--color-brand);
    border-left-width: 5px;
}

/* ===== 内容区 ===== */
.learn-content-area {
    flex: 1;
    padding: 20px 24px;
    min-height: 240px;
    animation: fadeIn 0.25s ease;
}

.learn-content-title {
    font-size: 17px;
    font-weight: 700;
    color: var(--color-brand-dark);
    margin-bottom: 12px;
    padding-bottom: 8px;
    border-bottom: 2px solid #e2e8f0;
}

.learn-content-body {
    font-size: 14px;
    line-height: 1.75;
    color: var(--text-secondary);
}

.learn-content-body p {
    margin-bottom: 10px;
}

.learn-content-body strong {
    color: var(--color-brand-dark);
    font-weight: 700;
}

.learn-content-body .formula {
    display: block;
    text-align: center;
    font-size: 16px;
    font-weight: 700;
    color: var(--color-brand);
    background: #f0f7ff;
    border-radius: var(--radius-sm);
    padding: 10px 16px;
    margin: 12px 0;
    font-family: "Cambria", "Times New Roman", serif;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(4px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ===== 导航栏 ===== */
/* 翻页导航（学习面板底部） */
.learn-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 6px;
    padding: 12px 16px;
    border-top: 1px solid #e2e8f0;
}

.learn-nav-btn {
    padding: 5px 10px;
    border: 1.5px solid #cbd5e1;
    border-radius: 6px;
    background: #fff;
    color: var(--text-secondary);
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.learn-nav-btn:hover:not(:disabled) {
    border-color: var(--color-brand);
    color: var(--color-brand);
    background: #f0f7ff;
}

.learn-nav-btn:active:not(:disabled) {
    transform: scale(0.97);
}

.learn-nav-btn:disabled {
    opacity: 0.35;
    cursor: not-allowed;
}

.learn-nav-pos {
    font-size: 13px;
    font-weight: 600;
    color: var(--text-muted);
    font-variant-numeric: tabular-nums;
}

/* ===== 列表样式 ===== */
.bullet-list {
    list-style: none;
    line-height: 1.7;
    font-size: 14px;
}

.bullet-list li {
    margin-bottom: 8px;
    padding-left: 16px;
    position: relative;
}

.bullet-list li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 10px;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--color-brand);
}

.bullet-list sup {
    font-size: 0.75em;
    vertical-align: super;
}

.try-list li {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 8px;
}

.try-text {
    flex: 1;
    min-width: 0;
}

.try-btn {
    flex-shrink: 0;
    padding: 7px 18px;
    border: none;
    border-radius: 14px;
    background: linear-gradient(135deg, #60a5fa 0%, #3182ce 100%);
    color: #fff;
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    box-shadow: 0 2px 8px rgba(49, 130, 206, 0.35);
}

.try-btn:hover {
    background: linear-gradient(135deg, #3182ce 0%, #1e3a5f 100%);
    box-shadow: 0 3px 12px rgba(49, 130, 206, 0.45);
    transform: translateY(-1px);
}

.try-btn:active {
    transform: scale(0.95);
    box-shadow: 0 1px 4px rgba(49, 130, 206, 0.3);
}

/* 误区对比 */
.compare-grid {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.compare-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

.compare-wrong,
.compare-right {
    font-size: 13px;
    line-height: 1.65;
    padding: 10px 12px;
    border-radius: var(--radius-sm);
}

.compare-wrong {
    background: #fff5f5;
    border-left: 3px solid var(--color-lift);
    color: #742a2a;
}

.compare-right {
    background: #f0fdf4;
    border-left: 3px solid #16a34a;
    color: #166534;
}

/* ==================== 桌面端暂停按钮样式（移动端隐藏） ==================== */
.pause-btn {
    width: 100%;
    padding: 8px;
    border: none;
    border-radius: var(--radius-sm);
    background: var(--color-brand);
    color: #fff;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    align-items: center;
    justify-content: center;
    gap: 6px;
    transition: background 0.2s, transform 0.15s;
    margin-bottom: 4px;
}

.pause-btn:hover {
    background: #2b6cb0;
    transform: translateY(-1px);
}

.pause-btn.paused {
    background: #38a169;
}

.pause-btn.paused:hover {
    background: #2f855a;
}

/* ==================== HUD 通用样式（侧边栏内使用） ==================== */
.hud-row {
    display: flex;
    align-items: center;
    gap: 5px;
    font-size: 12px;
    padding: 2px 0;
}

.hud-row .hud-label {
    flex: 1;
    color: var(--text-secondary);
}

.hud-row .hud-num {
    font-weight: 700;
    font-variant-numeric: tabular-nums;
    color: var(--text-primary);
}

.hud-upper .hud-label,
.hud-upper .hud-num {
    color: var(--color-upper);
}

.hud-lower .hud-label,
.hud-lower .hud-num {
    color: var(--color-lower);
}

.hud-muted .hud-label,
.hud-muted .hud-num {
    color: var(--text-muted);
    font-size: 11px;
}

.hud-icon {
    width: 10px;
    height: 10px;
    flex-shrink: 0;
}

.shape-circle {
    border-radius: 50%;
    background: var(--color-upper);
}

.shape-square {
    border-radius: 1px;
    background: var(--color-lower);
}

.hud-lift {
    margin-top: 6px;
    padding-top: 6px;
    border-top: 1px solid #e2e8f0;
    text-align: center;
}

.hud-lift-label {
    font-size: 11px;
    color: var(--text-muted);
    font-weight: 600;
    display: block;
    margin-bottom: 2px;
}

.hud-lift-value {
    font-size: 22px;
    font-weight: 800;
    color: var(--color-brand);
    font-variant-numeric: tabular-nums;
    line-height: 1.1;
    transition: color 0.3s;
}

/* ===== 升力数值左右箭头 ===== */
.hud-lift-row {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
}

.hud-arrow {
    font-size: 16px;
    opacity: 0;
    transition: opacity 0.3s;
    line-height: 1;
}

.hud-arrow-up {
    color: #dc2626;
}

.hud-arrow-up.active {
    opacity: 1;
}

.hud-arrow-down {
    color: #16a34a;
}

.hud-arrow-down.active {
    opacity: 1;
}

.hud-lift-value.negative {
    color: var(--color-lift-negative);
}

.hud-lift-value.zero {
    color: var(--text-muted);
}

/* ==================== 断点：md (640-1023px) 平板/小屏横屏 ==================== */
@media (min-width: 640px) and (max-width: 1023px) {
    .main-layout {
        display: grid;
        grid-template-columns: 200px 1fr;
        grid-template-areas:
            "sidebar canvasRow"
            "sidebar panel";
        gap: 16px;
        align-items: start;
    }

    .canvas-row { grid-area: canvasRow; order: unset; flex-direction: row; }
    .canvas-wrapper { order: unset; flex: 1; }
    .control-sidebar { grid-area: sidebar; order: unset; position: sticky; top: 20px; max-height: calc(100vh - 40px); overflow-y: auto; }
    .learn-panel { grid-area: panel; order: unset; }

    .pause-btn { display: none; }
    .pause-float { display: flex; }

    .sliders { display: flex; flex-direction: column; gap: 2px; }
}

/* ==================== 断点：lg (≥1024px) 桌面 ==================== */
@media (min-width: 1024px) {
    .main-layout {
        display: grid;
        grid-template-columns: 200px 1fr;
        grid-template-areas:
            "sidebar canvasRow"
            "sidebar panel";
        gap: 16px;
        align-items: start;
    }

    .canvas-row { grid-area: canvasRow; order: unset; flex-direction: row; }
    .canvas-wrapper { order: unset; flex: 1; }
    .control-sidebar { grid-area: sidebar; order: unset; position: sticky; top: 20px; max-height: calc(100vh - 40px); overflow-y: auto; }
    .learn-panel { grid-area: panel; order: unset; }

    .pause-btn { display: none; }
    .pause-float { display: flex; }

    .control-sidebar {
        padding: 14px 14px;
    }

    .sliders { gap: 2px; }

    .canvas-wrapper {
        padding: 12px;
    }

    .page-header h1 {
        font-size: 26px;
    }
}

/* ==================== 手机竖屏微调 (<640px) ==================== */
@media (max-width: 639px) {
    body {
        padding: 12px;
    }

    .page-header h1 {
        font-size: 20px;
    }

    .title-icon {
        width: 22px;
        height: 22px;
    }

    .teaching-note summary {
        font-size: 12px;
    }

    .teaching-note p {
        font-size: 12px;
        padding: 8px 12px;
    }

    .canvas-wrapper {
        padding: 8px;
    }

    /* 移动端飞机姿态面板：缩小尺寸 */
    .attitude-panel {
        width: 90px;
    }

    .attitude-stage {
        height: 200px;
    }

    .attitude-stage img {
        width: 75px;
        max-height: 50px;
    }

    /* 移动端画布高度适中，不过长 */
    canvas {
        height: max(300px, 40vh);
        width: 100%;
        object-fit: contain;
    }

    /* ===== 滑块卡片压缩 ===== */
    .control-sidebar {
        padding: 8px 10px;
    }

    .sliders {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 5px;
    }

    .slider-group {
        padding: 6px 10px;
    }

    .slider-header {
        margin-bottom: 4px;
    }

    .slider-label {
        font-size: 13px;
    }

    .slider-value {
        font-size: 14px;
    }

    .slider-group input[type="range"] {
        height: 9px;
    }

    .slider-group input[type="range"]::-webkit-slider-thumb {
        width: 28px;
        height: 28px;
        margin-top: -10px;
    }

    .slider-group input[type="range"]::-moz-range-thumb {
        width: 28px;
        height: 28px;
    }

    /* ===== 学习面板文字压缩 ===== */
    .bullet-list {
        font-size: 12px;
        line-height: 1.6;
    }

    .bullet-list li {
        margin-bottom: 5px;
        padding-left: 14px;
    }

    /* ===== 操作引导列表修复排版 ===== */
    .try-list li {
        flex-direction: row;
        align-items: center;
        justify-content: flex-start;
        gap: 6px;
        margin-bottom: 6px;
        padding-left: 14px;
        font-size: 12px;
        line-height: 1.5;
    }

    .try-list li > strong:first-child,
    .try-list li > strong {
        white-space: nowrap;
    }

    .try-btn {
        padding: 3px 10px;
        font-size: 11px;
        margin-left: auto;
        flex-shrink: 0;
    }

    /* ===== 误区对比压缩 ===== */
    .compare-grid {
        gap: 8px;
    }

    .compare-row {
        grid-template-columns: 1fr;
        gap: 6px;
    }

    .compare-wrong,
    .compare-right {
        font-size: 11px;
        padding: 6px 8px;
        line-height: 1.5;
    }

    /* ===== 学习面板移动端：仅内容区 + 导航 ===== */
    .learn-panel {
        min-height: auto;
    }

    /* 移动端：侧边索引栏隐藏，由 FAB 菜单替代 */
    .learn-index { display: none; }

    .learn-index-list {
        display: flex;
        flex-wrap: wrap;
        gap: 4px;
        padding: 0 12px;
    }

    .learn-index-item {
        padding: 5px 12px;
        border-left: none;
        border-radius: 14px;
        background: #f1f5f9;
        font-size: 12px;
    }

    .learn-index-item.active {
        border-left: none;
        border-radius: 14px;
    }

    .learn-category {
        margin-bottom: 4px;
    }

    .learn-category-title {
        padding: 6px 12px 2px;
        font-size: 11px;
    }

    .learn-content-area {
        padding: 14px 16px;
        min-height: 180px;
    }

    .learn-content-title {
        font-size: 15px;
    }

    .learn-content-body {
        font-size: 13px;
    }

    .learn-nav {
        padding: 14px 16px;
    }

    .learn-nav-btn {
        padding: 24px 44px;
        font-size: 30px;
        border-radius: 12px;
        min-height: 88px;
        border-width: 2.5px;
    }

    .learn-nav-pos {
        font-size: 20px;
    }

    /* 移动端公式块缩小 */
    .learn-content-body .formula {
        font-size: 14px;
        padding: 8px 12px;
        margin: 8px 0;
    }

    .status-alert {
        font-size: 11px;
        padding: 4px 12px;
    }

    /* ===== 移动端学习面板：回到正常文档流（在页面下方） ===== */
    .learn-panel {
        position: relative;
        transform: none;
        transition: none;
    }

    /* 浮动触发按钮（圆形纯图标，参照 F-15C manual 风格） */
    .learn-fab {
        position: fixed;
        right: 20px;
        bottom: 20px;
        width: 48px;
        height: 48px;
        padding: 0;
        border: none;
        border-radius: 50%;
        background: linear-gradient(135deg, #60a5fa 0%, #3182ce 100%);
        color: #fff;
        font-size: 20px;
        cursor: pointer;
        display: flex;
        align-items: center;
        justify-content: center;
        z-index: 998;
        box-shadow: 0 4px 20px rgba(49, 130, 206, 0.45);
        transition: transform 0.18s, box-shadow 0.18s;
    }

    .learn-fab:hover { transform: scale(1.1); }
    .learn-fab:active { transform: scale(0.95); }

    .learn-fab-label { display: none; }

    /* 整屏菜单遮罩（参照 F-15C manual：顶部标题栏 + 白色列表） */
    .learn-overlay {
        display: none;
        position: fixed;
        top: 0; left: 0; right: 0; bottom: 0;
        z-index: 1001;
        background: rgba(0, 0, 0, 0.5);
        opacity: 0;
        transition: opacity 0.3s;
        flex-direction: column;
        align-items: center;
        justify-content: flex-start;
        padding-top: 15vh;
    }

    .learn-overlay.show {
        display: flex;
        opacity: 1;
    }

    .learn-menu-header {
        display: flex;
        align-items: center;
        justify-content: space-between;
        width: 100%;
        max-width: 420px;
        padding: 14px 18px;
        background: linear-gradient(135deg, #3182ce, #1e3a5f);
        color: #fff;
        border-radius: 14px 14px 0 0;
        box-sizing: border-box;
    }

    .learn-menu-header h4 {
        font-size: 16px;
        font-weight: 700;
        letter-spacing: 0.5px;
    }

    .learn-menu-close {
        font-size: 26px;
        line-height: 1;
        cursor: pointer;
        padding: 2px 8px;
        opacity: 0.85;
    }

    .learn-menu-list {
        background: #fff;
        width: 100%;
        max-width: 420px;
        max-height: 60vh;
        overflow-y: auto;
        padding: 6px 0;
        border-radius: 0 0 14px 14px;
        box-sizing: border-box;
    }

    .learn-menu-item {
        display: flex;
        align-items: center;
        gap: 10px;
        padding: 12px 18px;
        border-bottom: 1px solid #f1f5f9;
        cursor: pointer;
        transition: background 0.15s;
    }

    .learn-menu-item:active { background: #f0f7ff; }

    .learn-menu-item.active {
        background: rgba(49, 130, 206, 0.08);
        border-left: 3px solid #3182ce;
    }

    .learn-menu-group {
        font-size: 11px;
        color: #64748b;
        background: #f1f5f9;
        border-radius: 4px;
        padding: 2px 6px;
        white-space: nowrap;
        flex-shrink: 0;
    }

    .learn-menu-item.active .learn-menu-group {
        color: #3182ce;
        background: rgba(49, 130, 206, 0.1);
    }

    .learn-menu-title {
        font-size: 14px;
        color: #1e293b;
        font-weight: 500;
    }

    .learn-menu-item.active .learn-menu-title {
        color: #3182ce;
        font-weight: 600;
    }
}

/* 桌面端隐藏浮动按钮和菜单遮罩 */
@media (min-width: 640px) {
    .learn-fab { display: none; }
    .learn-overlay { display: none; }
}