/* Visual practice canvas — Paint-style workspace for Visual learners */
.lb-visual-workspace,
.lb-visual-canvas-mount,
.exercise-visual-canvas-wrap {
    width: 100%;
    max-width: 100%;
    min-width: 0;
    box-sizing: border-box;
}

.lb-visual-workspace {
    margin-top: 1rem;
}

.lb-visual-workspace-hint {
    margin: 0 0 0.65rem;
    font-size: 0.8125rem;
    color: var(--text-secondary, #64748b);
    line-height: 1.5;
}

.lb-vpc {
    border: 1px solid var(--border-color, #e2e8f0);
    border-radius: var(--lb-radius, 0.75rem);
    overflow: hidden;
    background: var(--bg-card, #fff);
    box-shadow: 0 2px 12px rgba(15, 23, 42, 0.06);
    width: 100%;
    max-width: 100%;
    min-width: 0;
    box-sizing: border-box;
}

.lb-vpc-toolbar {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.35rem;
    padding: 0.55rem 0.65rem;
    background: var(--bg-secondary, #f8fafc);
    border-bottom: 1px solid var(--border-color, #e2e8f0);
    max-width: 100%;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: thin;
}

.lb-vpc-tool,
.lb-vpc-action {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.4rem 0.55rem;
    border: 1px solid var(--border-color, #e2e8f0);
    border-radius: 0.5rem;
    background: var(--bg-primary, #fff);
    color: var(--text-primary, #0f172a);
    font-size: 0.72rem;
    font-weight: 600;
    cursor: pointer;
    transition: border-color 0.15s, background 0.15s;
    flex-shrink: 0;
}

.lb-vpc-tool span {
    display: none;
}

.lb-vpc-tool.active,
.lb-vpc-action:hover,
.lb-vpc-tool:hover {
    border-color: var(--accent-primary, #2563eb);
    background: color-mix(in srgb, var(--accent-primary, #2563eb) 8%, var(--bg-primary, #fff));
}

.lb-vpc-tool.active {
    background: color-mix(in srgb, var(--accent-primary, #2563eb) 14%, var(--bg-primary, #fff));
    color: var(--accent-primary, #2563eb);
}

.lb-vpc-sep {
    width: 1px;
    height: 1.5rem;
    background: var(--border-color, #e2e8f0);
    margin: 0 0.15rem;
    flex-shrink: 0;
}

.lb-vpc-color {
    width: 1.35rem;
    height: 1.35rem;
    border-radius: 50%;
    border: 2px solid var(--border-color, #e2e8f0);
    background: var(--vpc-color, #2563eb);
    cursor: pointer;
    padding: 0;
    flex-shrink: 0;
}

.lb-vpc-color.active {
    border-color: var(--text-primary, #0f172a);
    box-shadow: 0 0 0 2px var(--bg-primary, #fff), 0 0 0 4px var(--accent-primary, #2563eb);
}

.lb-vpc-width {
    width: 1.65rem;
    height: 1.65rem;
    border-radius: 0.4rem;
    border: 1px solid var(--border-color, #e2e8f0);
    background: var(--bg-primary, #fff);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    padding: 0;
    flex-shrink: 0;
}

.lb-vpc-width span {
    display: block;
    border-radius: 50%;
    background: var(--text-primary, #0f172a);
}

.lb-vpc-width.active {
    border-color: var(--accent-primary, #2563eb);
}

.lb-vpc-actions {
    display: inline-flex;
    gap: 0.25rem;
    margin-left: auto;
    flex-shrink: 0;
}

.lb-vpc-stage {
    position: relative;
    padding: 0.65rem;
    background: linear-gradient(160deg, rgba(15, 23, 42, 0.04), rgba(30, 41, 59, 0.02));
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
}

.lb-vpc-canvas-wrap {
    position: relative;
    width: 100%;
    max-width: 100%;
    min-width: 0;
}

.lb-vpc-overlay {
    position: absolute;
    inset: 0;
    pointer-events: none;
    z-index: 2;
}

.lb-vpc-resize-handle {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.45rem;
    margin-top: 0.45rem;
    padding: 0.45rem 0.65rem;
    border: 1px dashed var(--border-color, #cbd5e1);
    border-radius: 0.5rem;
    background: var(--bg-primary, #fff);
    color: var(--text-muted, #64748b);
    font-size: 0.68rem;
    font-weight: 600;
    cursor: ns-resize;
    touch-action: none;
    user-select: none;
    -webkit-user-select: none;
}

.lb-vpc-resize-handle i {
    opacity: 0.75;
}

.lb-vpc-resize-handle:hover,
.lb-vpc-stage.lb-vpc-resizing .lb-vpc-resize-handle {
    border-color: var(--accent-primary, #2563eb);
    color: var(--accent-primary, #2563eb);
    background: color-mix(in srgb, var(--accent-primary, #2563eb) 6%, var(--bg-primary, #fff));
}

.lb-vpc-stage.lb-vpc-resizing .lb-vpc-canvas {
    outline: 2px solid color-mix(in srgb, var(--accent-primary, #2563eb) 35%, transparent);
    outline-offset: 1px;
}

.lb-vpc-text-input {
    display: none;
}

/* Paint-style text / math layers on overlay */
.lb-vpc-text-object,
.lb-vpc-text-editor-box {
    pointer-events: auto;
}

.lb-vpc-text-object {
    position: absolute;
    z-index: 4;
    box-sizing: border-box;
    border: 2px solid transparent;
    border-radius: 0.45rem;
    background: transparent;
    box-shadow: none;
    min-width: 0;
    min-height: 0;
    cursor: default;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

/* MS Word-style: chrome only while selected */
.lb-vpc-text-object.selected {
    border-color: rgba(37, 99, 235, 0.55);
    background: rgba(15, 23, 42, 0.88);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.25), 0 0 0 3px rgba(37, 99, 235, 0.2);
    min-width: 80px;
    min-height: 48px;
    cursor: move;
}

.lb-vpc-text-object-bar {
    display: none;
}

.lb-vpc-text-object.selected .lb-vpc-text-object-bar,
.lb-vpc-text-editor-bar {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.25rem 0.45rem;
    background: rgba(37, 99, 235, 0.25);
    color: #e2e8f0;
    font-size: 0.65rem;
    font-weight: 600;
    cursor: grab;
    user-select: none;
    touch-action: none;
    border-bottom: 1px solid rgba(148, 163, 184, 0.25);
}

.lb-vpc-text-object.dragging .lb-vpc-text-object-bar,
.lb-vpc-text-editor-box .lb-vpc-text-editor-bar:active {
    cursor: grabbing;
}

.lb-vpc-text-object-content,
.lb-vpc-text-object-body {
    padding: 0.15rem 0.2rem;
    color: #f8fafc;
    line-height: 1.45;
    word-break: break-word;
    overflow: auto;
    flex: 1;
    min-height: 0;
}

.lb-vpc-text-object.selected .lb-vpc-text-object-content {
    padding: 0.45rem 0.55rem;
}

.lb-vpc-text-object-content .katex {
    color: inherit;
    font-size: 1.05em;
}

.lb-vpc-text-object-resize {
    display: none;
}

.lb-vpc-text-object.selected .lb-vpc-text-object-resize,
.lb-vpc-text-editor-resize {
    display: block;
    position: absolute;
    right: 0;
    bottom: 0;
    width: 18px;
    height: 18px;
    cursor: nwse-resize;
    touch-action: none;
    background: linear-gradient(135deg, transparent 45%, rgba(37, 99, 235, 0.9) 45%);
    border-radius: 0 0 0.35rem 0;
    z-index: 2;
}

.lb-vpc-text-editor-box {
    position: absolute;
    z-index: 8;
    box-sizing: border-box;
    border: 2px solid var(--accent-primary, #2563eb);
    border-radius: 0.5rem;
    background: rgba(15, 23, 42, 0.94);
    box-shadow: 0 8px 28px rgba(0, 0, 0, 0.35);
    min-width: 120px;
    min-height: 56px;
    display: flex;
    flex-direction: column;
}

.lb-vpc-text-editor-input-wrap {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding: 0.35rem 0.45rem;
    min-height: 2.5rem;
    min-width: 0;
    overflow: hidden;
}

.lb-vpc-text-editor-input,
.lb-vpc-text-editor-input-wrap .lb-vpc-math-field,
.lb-vpc-text-editor-input-wrap .lb-vpc-math-fallback-input {
    width: 100%;
    min-height: 2.25rem;
    border: none;
    background: transparent;
    color: #f8fafc;
    font-family: system-ui, -apple-system, Segoe UI, sans-serif;
    font-size: 1rem;
    font-weight: 600;
    line-height: 1.4;
    resize: none;
    outline: none;
    box-sizing: border-box;
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
    white-space: pre-wrap;
    word-break: break-word;
}

.lb-vpc-text-editor-input-wrap math-field {
    width: 100%;
    min-height: 2.5rem;
    font-size: 1.1rem;
    color: #f8fafc;
    background: transparent;
    border: none;
}

.lb-vpc-text-editor-actions {
    display: flex;
    gap: 0.35rem;
    padding: 0.25rem 0.4rem 0.35rem;
    justify-content: flex-end;
}

.lb-vpc-text-editor-btn {
    width: 1.75rem;
    height: 1.75rem;
    border: none;
    border-radius: 0.35rem;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
}

.lb-vpc-text-editor-btn.ok {
    background: var(--success-500, #10b981);
    color: #fff;
}

.lb-vpc-text-editor-btn.keyboard {
    background: rgba(37, 99, 235, 0.85);
    color: #fff;
}

.lb-vpc-text-editor-btn.cancel {
    background: rgba(148, 163, 184, 0.35);
    color: #f8fafc;
}

.lb-vpc-math-loading {
    color: #94a3b8;
    font-size: 0.85rem;
    padding: 0.35rem 0;
}

.lb-vpc-math-btn span {
    font-size: 0.7rem;
}

.lb-vpc-code-editor-input,
.lb-vpc-code-body {
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace !important;
    font-size: 13px !important;
    line-height: 1.45 !important;
    tab-size: 4;
    white-space: pre-wrap;
}

.lb-vpc-width-font .lb-vpc-font-preview {
    font-weight: 700;
    line-height: 1;
    color: var(--text-primary, #0f172a);
}

.lb-vpc-canvas {
    display: block;
    width: 100%;
    max-width: 100%;
    touch-action: none;
    cursor: crosshair;
    border-radius: 0.55rem;
    border: 1px solid rgba(100, 116, 139, 0.35);
    --vpc-bg: #0f172a;
    background: var(--vpc-bg);
    box-sizing: border-box;
}

/* Select tool — scroll-friendly on touch; default tool on mount */
.lb-vpc.lb-vpc-tool-select .lb-vpc-canvas {
    touch-action: pan-y;
    cursor: default;
}

.lb-vpc.lb-vpc-tool-select .lb-vpc-overlay {
    pointer-events: none;
}

.lb-vpc.lb-vpc-tool-select .lb-vpc-text-object {
    pointer-events: auto;
}

[data-theme="dark"] .lb-vpc-canvas {
    --vpc-bg: #020617;
}

.lb-vpc-status {
    padding: 0.45rem 0.75rem;
    font-size: 0.68rem;
    color: var(--text-muted, #94a3b8);
    border-top: 1px solid var(--border-color, #e2e8f0);
    background: var(--bg-secondary, #f8fafc);
}

.lb-vpc-status i {
    margin-right: 0.35rem;
    opacity: 0.85;
}

/* Exercise section visual canvas — legacy wrapper (funnel demos); prefer lb-visual-workspace */
.exercise-visual-canvas-wrap {
    border-radius: 0.75rem;
    overflow: visible;
    border: none;
    width: 100%;
    max-width: 100%;
}

.exercise-visual-toolbar-note {
    padding: 0.65rem 0.85rem;
    background: color-mix(in srgb, var(--accent-primary, #2563eb) 8%, var(--bg-secondary, #f8fafc));
    border-bottom: 1px solid var(--border-color, #e2e8f0);
    font-size: 0.8125rem;
    color: var(--text-secondary, #475569);
    display: flex;
    align-items: flex-start;
    gap: 0.5rem;
    line-height: 1.45;
}

.exercise-visual-notes {
    margin-top: 0.75rem;
}

.exercise-visual-notes textarea {
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
}

/* Home lesson shell — canvas mounts share theory-block workspace layout */
.lesson-main-content .lb-visual-canvas-mount,
.lesson-main-content .lb-visual-workspace,
.lesson-main-content .lb-canvas-workspace-shell {
    max-width: 100%;
    min-width: 0;
}

@media (min-width: 640px) {
    .lb-vpc-tool span {
        display: inline;
    }
}
@media (max-width: 900px) {
    .lb-vpc-toolbar {
        gap: 0.3rem;
        padding: 0.5rem 0.55rem;
    }

    .lb-vpc-stage {
        padding: 0.5rem;
    }

    .exercise-visual-toolbar-note {
        font-size: 0.8rem;
        padding: 0.6rem 0.75rem;
    }

    .lesson-main-content #notes-section .section-title {
        font-size: 1.25rem !important;
    }
}

/* Mobile canvas — single ≤500px block (no per-width hacks) */
@media (max-width: 500px) {
    .lb-vpc {
        width: 100%;
        max-width: 100%;
        min-width: 0;
    }

    .lb-vpc-toolbar {
        flex-wrap: nowrap;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        scrollbar-width: thin;
        gap: 0.35rem;
        padding: 0.45rem 0.5rem;
        max-width: 100%;
    }

    .lb-vpc-tool,
    .lb-vpc-action {
        min-width: 40px;
        min-height: 40px;
        padding: 0.4rem;
        flex-shrink: 0;
        justify-content: center;
    }

    .lb-vpc-sep {
        display: none;
    }

    .lb-vpc-actions {
        margin-left: auto;
        flex-shrink: 0;
        flex-wrap: nowrap;
        justify-content: flex-end;
        width: auto;
        padding-top: 0;
        border-top: none;
    }

    .lb-vpc-stage {
        padding: 0.4rem;
    }

    .lb-vpc-resize-handle span {
        display: none;
    }

    .lb-vpc-status {
        font-size: 0.65rem;
        padding: 0.35rem 0.5rem;
        display: flex;
        align-items: center;
        gap: 0.25rem;
    }

    .lb-vpc-text-editor-box {
        min-width: 100px;
        max-width: calc(100% - 8px);
    }

    .lb-visual-workspace-hint {
        font-size: 0.8125rem;
        line-height: 1.45;
    }

    .lb-workspace-label {
        font-size: 0.68rem;
    }

    .lesson-main-content #notes-section {
        margin: 1rem 0 !important;
        padding: 0 !important;
    }

    .lesson-main-content #notes-section .notes-toolbar span {
        font-size: 0.75rem;
    }

    .lesson-main-content #notes-section .notes-toolbar span strong {
        font-weight: 600;
    }
}

/* Phase D+ — math insert popover */
.lb-vpc-math-popover {
    position: absolute;
    top: 0.5rem;
    left: 0.5rem;
    right: 0.5rem;
    z-index: 12;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    align-items: center;
    padding: 0.65rem;
    background: var(--bg-card, #fff);
    border: 1px solid var(--border-color, #e2e8f0);
    border-radius: 0.65rem;
    box-shadow: var(--shadow-medium, 0 4px 12px rgba(0, 0, 0, 0.12));
}

.lb-vpc-math-field,
.lb-vpc-math-fallback-input {
    flex: 1 1 180px;
    min-width: 140px;
    padding: 0.45rem 0.6rem;
    border: 1px solid var(--border-color, #e2e8f0);
    border-radius: 0.45rem;
    font-size: 1rem;
}

.lb-vpc-math-done {
    padding: 0.45rem 0.85rem;
    border-radius: 0.45rem;
    border: none;
    background: var(--blue-600, #2563eb);
    color: #fff;
    cursor: pointer;
}

.lb-vpc-math-btn span {
    font-size: 0.7rem;
}

.lb-vpc-code-editor-input,
.lb-vpc-code-body {
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace !important;
    font-size: 13px !important;
    line-height: 1.45 !important;
    tab-size: 4;
    white-space: pre-wrap;
}