:root {
    --primary: #1db954;
    --primary-dark: #1aa34a;
    --primary-light: #1ed760;
    --error: #e22134;

    --bg-primary: #000000;
    --bg-secondary: #121212;
    --bg-tertiary: #181818;
    --bg-elevated: #282828;
    --text-primary: #ffffff;
    --text-secondary: #b3b3b3;
    --text-muted: #6a6a6a;

    --glass-border: rgba(29, 185, 84, 0.1);
    --canvas-grid-dot: rgba(255, 255, 255, 0.06);

    --keyword-purple: #bd93f9;
    --keyword-blue: #8be9fd;
    --keyword-green: #6272a4;
    --keyword-orange: #ffb86c;
    --keyword-red: #ff5555;
    --keyword-yellow: #f1fa8c;

    /* Scratch-inspired block category colors */
    --cat-pins: #4c97ff;
    --cat-pins-dark: #3373cc;
    --cat-sound: #cf63cf;
    --cat-sound-dark: #bd42bd;
    --cat-control: #ffab19;
    --cat-control-dark: #cf8b17;
    --cat-serial: #9966ff;
    --cat-serial-dark: #774dcb;
    --cat-variables: #ff8c1a;
    --cat-variables-dark: #db6e00;
    --cat-servo: #17c3b2;
    --cat-servo-dark: #109c8e;
    --cat-hat: #ffbf00;
    --cat-hat-dark: #e0a800;

    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;

    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;

    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.5);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.6);
    --shadow-glow: 0 0 30px rgba(29, 185, 84, 0.3);

    --transition-fast: 150ms ease;
}

:root[data-theme="light"] {
    --primary-light: #128a3e;

    --bg-primary: #ffffff;
    --bg-secondary: #f5f6f7;
    --bg-tertiary: #eceef1;
    --bg-elevated: #dfe3e8;
    --text-primary: #14181c;
    --text-secondary: #4b5563;
    --text-muted: #8a94a6;

    --glass-border: rgba(0, 0, 0, 0.1);
    --canvas-grid-dot: rgba(0, 0, 0, 0.07);

    --shadow-sm: 0 1px 3px rgba(20, 24, 28, 0.08);
    --shadow-md: 0 4px 10px rgba(20, 24, 28, 0.12);
    --shadow-glow: 0 0 24px rgba(29, 185, 84, 0.25);

    --keyword-purple: #a626a4;
    --keyword-blue: #4078f2;
    --keyword-green: #a0a1a7;
    --keyword-orange: #c18401;
    --keyword-red: #ca1243;
    --keyword-yellow: #50a14f;
}

* {
    box-sizing: border-box;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    border: none;
    border-radius: var(--radius-md);
    padding: 0.5rem 1rem;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition-fast);
}
.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}
.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    color: #06210f;
}
.btn-primary:hover:not(:disabled) {
    transform: translateY(-1px);
    box-shadow: var(--shadow-glow);
}
.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--glass-border);
}
.btn-secondary:hover:not(:disabled) {
    color: var(--primary-light);
    border-color: var(--primary);
}

.label {
    display: block;
    font-size: 0.72rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
    margin-bottom: 4px;
}

.input {
    width: 100%;
    background: var(--bg-tertiary);
    border: 2px solid transparent;
    border-radius: var(--radius-md);
    color: var(--text-primary);
    padding: 0.5rem 0.65rem;
    font-size: 0.85rem;
    transition: var(--transition-fast);
}
.input:focus {
    outline: none;
    background: var(--bg-elevated);
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(29, 185, 84, 0.1);
}

.keyword-purple {
    color: var(--keyword-purple);
    font-weight: 600;
}
.keyword-blue {
    color: var(--keyword-blue);
    font-style: italic;
}
.keyword-green {
    color: var(--keyword-green);
}
.keyword-orange {
    color: var(--keyword-orange);
}
.keyword-red {
    color: var(--keyword-red);
}
.keyword-yellow {
    color: var(--keyword-yellow);
}

html,
body,
#app {
    height: 100%;
    margin: 0;
}

body {
    background: var(--bg-primary);
    color: var(--text-primary);
    font-family:
        -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}
::-webkit-scrollbar-track {
    background: transparent;
}
::-webkit-scrollbar-thumb {
    background: var(--bg-elevated);
    border-radius: var(--radius-sm);
}

#app {
    display: flex;
    flex-direction: column;
    height: 100vh;
    overflow: hidden;
}

/* Toolbar */
#toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--glass-border);
    box-shadow: var(--shadow-sm);
    z-index: 5;
}

.toolbar-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 700;
    font-size: 1.05rem;
}

.brand-mark {
    color: var(--primary);
}

.toolbar-controls {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.speed-control {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 0.78rem;
    color: var(--text-secondary);
}

.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    padding: 0;
    border-radius: 50%;
    background: var(--bg-elevated);
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
    font-size: 1rem;
    line-height: 1;
    cursor: pointer;
    transition: var(--transition-fast);
}
.theme-toggle:hover {
    border-color: var(--primary);
    transform: rotate(15deg);
}

.status-badge {
    padding: 3px 10px;
    border-radius: var(--radius-lg);
    font-size: 0.72rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}
.status-idle {
    background: var(--bg-elevated);
    color: var(--text-secondary);
}
.status-running {
    background: rgba(29, 185, 84, 0.15);
    color: var(--primary-light);
    box-shadow: 0 0 0 1px rgba(29, 185, 84, 0.3);
}
.status-error {
    background: rgba(226, 33, 52, 0.15);
    color: var(--error);
    box-shadow: 0 0 0 1px rgba(226, 33, 52, 0.3);
}

/* Workspace layout */
#workspace {
    flex: 1;
    display: grid;
    grid-template-columns: 240px 1fr 380px;
    min-height: 0;
}

.sidebar {
    background: var(--bg-secondary);
    display: flex;
    flex-direction: column;
    min-height: 0;
    border-right: 1px solid var(--glass-border);
}
#right-sidebar {
    border-right: none;
    border-left: 1px solid var(--glass-border);
}

.sidebar-tabs {
    display: flex;
    border-bottom: 1px solid var(--glass-border);
    flex-shrink: 0;
}
.sidebar-tab {
    flex: 1;
    background: none;
    border: none;
    color: var(--text-secondary);
    padding: var(--spacing-sm);
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition-fast);
    border-bottom: 2px solid transparent;
}
.sidebar-tab:hover {
    color: var(--text-primary);
}
.sidebar-tab.active {
    color: var(--primary-light);
    border-bottom-color: var(--primary);
}

.sidebar-panel {
    display: none;
    flex-direction: column;
    min-height: 0;
    flex: 1;
    overflow: auto;
    padding: var(--spacing-md);
}
.sidebar-panel.active {
    display: flex;
}

/* Left sidebar: Components and Lessons share one scrollable column instead
   of separate tabs, so you never lose sight of the palette while working
   through a lesson (or vice versa). */
.sidebar-scroll {
    flex: 1;
    min-height: 0;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    padding: var(--spacing-md);
}
.sidebar-section-title {
    margin: 0 0 var(--spacing-sm);
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
    font-weight: 700;
}

/* Palette */
#palette {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    width: 100%;
}
.palette-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    background: var(--bg-tertiary);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    padding: var(--spacing-sm);
    cursor: grab;
    transition: var(--transition-fast);
}
.palette-item:hover {
    background: var(--bg-elevated);
    border-color: var(--primary);
    transform: translateY(-1px);
}
.palette-icon {
    font-size: 1.3rem;
}
.palette-label {
    font-size: 0.85rem;
}

/* Canvas */
#canvas-wrap {
    position: relative;
    overflow: hidden;
    background:
        radial-gradient(
                circle at 1px 1px,
                var(--canvas-grid-dot) 1px,
                transparent 0
            )
            0 0/24px 24px,
        var(--bg-primary);
    cursor: grab;
    user-select: none;
    -webkit-user-select: none;
}
#canvas-wrap:active {
    cursor: grabbing;
}

#device-layer,
#wire-layer {
    position: absolute;
    top: 0;
    left: 0;
    width: 4000px;
    height: 3000px;
    transform-origin: 0 0;
}
#wire-layer {
    pointer-events: none;
    overflow: visible;
}

/* The visible stroke never receives events (a 2.5px line is too thin to grab
   reliably) — a fatter transparent `.wire-hit` line stacked on top of it does
   the actual clicking/dragging. `:has()` lets hovering the hit-line highlight
   its sibling visible line. */
#wire-layer .wire {
    stroke: var(--primary-light);
    stroke-width: 2.5;
    fill: none;
    pointer-events: none;
}
#wire-layer .wire-group:has(.wire-hit:hover) .wire {
    stroke: var(--error);
}
#wire-layer .wire-hit {
    stroke: transparent;
    stroke-width: 14;
    fill: none;
    pointer-events: stroke;
    cursor: pointer;
}
#wire-layer .wire-pending {
    stroke: var(--text-secondary);
    stroke-dasharray: 5 4;
    pointer-events: none;
}

#wire-layer .wire-waypoint {
    fill: var(--bg-tertiary);
    stroke: var(--primary-light);
    stroke-width: 2;
    pointer-events: auto;
    cursor: move;
}
#wire-layer .wire-group:has(.wire-hit:hover) .wire-waypoint,
#wire-layer .wire-waypoint:hover {
    fill: var(--primary);
    r: 5.5;
}

.device-node {
    position: absolute;
}
.device-node.selected .device-body > * {
    box-shadow:
        0 0 0 2px var(--primary),
        var(--shadow-glow);
}

.device-body {
    position: relative;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 6px;
}

.uno-board {
    position: relative;
    width: 100%;
    height: 100%;
    background: linear-gradient(160deg, #0f6e8c, #0a4a60);
    border-radius: 10px;
    border: 1px solid rgba(255, 255, 255, 0.12);
    box-shadow:
        var(--shadow-md),
        inset 0 1px 0 rgba(255, 255, 255, 0.12);
}

.mount-hole {
    position: absolute;
    width: 9px;
    height: 9px;
    border-radius: 50%;
    background: radial-gradient(circle, #fff 45%, #b8bfc6 70%, transparent 75%);
}

.mount-hole-tr {
    left: 334px;
    top: 14px;
}
.mount-hole-bl {
    left: 16px;
    top: 196px;
}
.mount-hole-br {
    left: 334px;
    top: 196px;
}

.usb-connector {
    position: absolute;
    left: -16px;
    top: 44px;
    width: 48px;
    height: 42px;
    background: linear-gradient(160deg, #d8dde2, #9aa3ac);
    border: 1px solid #6b737b;
    border-radius: 2px;
    box-shadow: inset 0 0 0 3px #b7bec5;
}

.power-jack {
    position: absolute;
    left: -12px;
    top: 146px;
    width: 26px;
    height: 40px;
    background: #16181c;
    border: 1px solid #000;
    border-radius: 3px 12px 12px 3px;
}
.power-jack::after {
    content: "";
    position: absolute;
    top: 2px;
    width: 40px;
    height: 34px;
    background: #16181c;
    border-radius: 8px;
}

.voltage-regulator {
    position: absolute;
    left: 40px;
    top: 98px;
    width: 22px;
    height: 14px;
    background: #14161a;
    border-radius: 2px;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.5);
}

.reset-button {
    position: absolute;
    left: 20px;
    top: 8px;
    width: 29px;
    height: 24px;
    background: linear-gradient(160deg, #d8dde2, #9aa3ac);
    border-radius: 2px;
}
.reset-cap {
    position: absolute;
    left: 7px;
    top: 5px;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: radial-gradient(circle at 35% 30%, #c0392b, #7a1f16 70%);
    border: 1px solid #4a1108;
}
.reset-leg {
    position: absolute;
    top: 8px;
    width: 4px;
    height: 8px;
    background: linear-gradient(160deg, #d8dde2, #9aa3ac);
}
.reset-leg-left {
    left: -4px;
}
.reset-leg-right {
    right: -4px;
}
.reset-label {
    left: 22px;
    top: 34px;
}

.icsp-header {
    position: absolute;
    width: 24px;
    height: 16px;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(2, 1fr);
    gap: 3px;
    background: #14161a;
    padding: 2px;
    border-radius: 2px;
}
.icsp-header span {
    width: 4px;
    height: 4px;
    border-radius: 50%;
    background: #d8dde2;
}
.icsp2-header {
    left: 68px;
    top: 20px;
}
.icsp-main-header {
    left: 326px;
    top: 100px;
    rotate: 90deg;
}

.serial-chip {
    position: absolute;
    left: 108px;
    top: 64px;
    width: 26px;
    height: 20px;
    background: #14161a;
    border-radius: 2px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.5);
}

.mcu-chip {
    position: absolute;
    left: 120px;
    top: 126px;
    width: 180px;
    height: 38px;
    background: #14161a;
    border-radius: 2px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
}
.mcu-label {
    color: #cfd3d8;
    font-size: 0.55rem;
    letter-spacing: 0.5px;
}

.capacitor {
    position: absolute;
    width: 22px;
    aspect-ratio: 1;
    border-radius: 50%;
    background: radial-gradient(circle at 35% 25%, #7e8388, #2a2e33 60%);
    border: 1px solid #000;
}
.capacitor-1 {
    left: 66px;
    top: 170px;
}
.capacitor-2 {
    left: 90px;
    top: 170px;
}

.onboard-led {
    position: absolute;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: #143a24;
}
.onboard-led-on {
    left: 340px;
    top: 66px;
    background: var(--primary-light);
    box-shadow: 0 0 6px 2px rgba(29, 185, 84, 0.7);
}
.onboard-led-l {
    --led-glow: 0;
    left: 141px;
    top: 42px;
    width: 8px;
    height: 6px;
    border-radius: 1px;
    background: #7a2a1e;
    box-shadow: 0 0 calc(2px + 8px * var(--led-glow))
        rgba(255, 90, 60, var(--led-glow));
    opacity: calc(0.4 + 0.6 * var(--led-glow));
    transition:
        box-shadow 60ms linear,
        opacity 60ms linear;
}
.onboard-led-tx,
.onboard-led-rx {
    width: 8px;
    height: 5px;
    border-radius: 1px;
    background: #8a8f94;
}
.onboard-led-tx {
    left: 142px;
    top: 66px;
}
.onboard-led-rx {
    left: 142px;
    top: 78px;
}

.silk-tiny {
    position: absolute;
    color: rgba(255, 255, 255, 0.75);
    font-size: 0.42rem;
    font-weight: 700;
    letter-spacing: 0.5px;
    pointer-events: none;
}
.icsp1-label {
    left: 310px;
    top: 103px;
    rotate: -90deg;
}
.icsp2-label {
    left: 68px;
    top: 40px;
}
.serial-label-tx {
    left: 152px;
    top: 64px;
}
.serial-label-rx {
    left: 152px;
    top: 76px;
}
.led-label-l {
    left: 153px;
    top: 41px;
}
.on-label {
    left: 324px;
    top: 64px;
}

.arduino-logo {
    position: absolute;
    left: 190px;
    top: 54px;
    opacity: 0.9;
}

.uno-badge {
    position: absolute;
    left: 235px;
    top: 54px;
    width: 56px;
    height: 32px;
    border: 2px dashed rgba(255, 255, 255, 0.7);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-weight: 700;
    font-size: 1rem;
    letter-spacing: 0.03px;
}

.uno-silk {
    position: absolute;
    color: rgba(255, 255, 255, 0.75);
    letter-spacing: 1px;
    pointer-events: none;
}

.uno-silk-brand {
    left: 190px;
    top: 79px;
    font-size: 0.42rem;
    font-weight: 600;
    letter-spacing: 0.05;
}

.led-bulb {
    --led-color: #ff3b30;
    --led-glow: 0;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: radial-gradient(circle at 35% 30%, #fff8, var(--led-color) 60%);
    box-shadow: 0 0 calc(6px + 26px * var(--led-glow))
        calc(2px + 10px * var(--led-glow)) var(--led-color);
    opacity: calc(0.35 + 0.65 * var(--led-glow));
    transition:
        box-shadow 60ms linear,
        opacity 60ms linear;
}

.device-label {
    font-size: 0.68rem;
    color: var(--text-secondary);
    text-align: center;
    max-width: 92px;
}

.button-cap {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-sm);
    background: var(--bg-elevated);
    border: 2px solid var(--glass-border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    cursor: pointer;
    user-select: none;
    transition: var(--transition-fast);
}
.button-cap.pressed {
    background: var(--primary);
    transform: translateY(2px);
}

.pot-dial {
    --angle: -135deg;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--bg-elevated);
    border: 2px solid var(--glass-border);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: grab;
    position: relative;
}
.pot-dial::after {
    content: "";
    position: absolute;
    top: 4px;
    left: 50%;
    width: 2px;
    height: 15px;
    background: var(--primary-light);
    transform-origin: bottom center;
    transform: translateX(-50%) rotate(var(--angle));
}

.buzzer-body {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--bg-elevated);
    border: 2px solid var(--glass-border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    transition: var(--transition-fast);
}
.buzzer-body.active {
    border-color: var(--primary);
    box-shadow: 0 0 12px 2px rgba(29, 185, 84, 0.5);
}

.ldr-body {
    --ldr-glow: 0;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--bg-elevated);
    border: 2px solid var(--glass-border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    box-shadow: 0 0 calc(4px + 16px * var(--ldr-glow)) rgba(255, 214, 10, var(--ldr-glow));
    transition: var(--transition-fast);
}

.servo-body {
    width: 44px;
    height: 44px;
    border-radius: var(--radius-sm);
    background: var(--bg-elevated);
    border: 2px solid var(--glass-border);
    display: flex;
    align-items: center;
    justify-content: center;
}
.servo-horn {
    --servo-angle: 0deg;
    font-size: 1.2rem;
    transform: rotate(var(--servo-angle));
    transition: transform 120ms linear;
}

.pir-body {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--bg-elevated);
    border: 2px solid var(--glass-border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    cursor: pointer;
    user-select: none;
    transition: var(--transition-fast);
}
.pir-body.active {
    border-color: var(--primary);
    box-shadow: 0 0 12px 2px rgba(255, 149, 0, 0.5);
}

.ports-layer {
    position: absolute;
    inset: 0;
    pointer-events: none;
}
.port-group {
    position: absolute;
    display: flex;
    flex-direction: column;
    align-items: center;
    transform: translateX(-50%);
}
.port-group.label-above {
    flex-direction: column-reverse;
    transform: translate(-50%, -100%);
}

.port {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--bg-tertiary);
    border: 2px solid var(--text-secondary);
    pointer-events: auto;
    cursor: crosshair;
    transition: var(--transition-fast);
    flex-shrink: 0;
}
.port:hover {
    background: var(--primary);
    border-color: var(--primary-light);
    transform: scale(1.3);
}
.port-label {
    font-size: 0.55rem;
    color: var(--text-secondary);
    white-space: nowrap;
    line-height: 1.6;
    pointer-events: none;
    transform-origin: top center;
}
.port-group.label-above .port-label {
    transform-origin: bottom center;
}

.inspector-section {
    margin-bottom: var(--spacing-md);
    width: 100%;
}
.inspector-empty {
    color: var(--text-muted);
    font-size: 0.85rem;
    padding: var(--spacing-md) 0;
}
.wiring-row {
    display: flex;
    justify-content: space-between;
    font-size: 0.8rem;
    padding: 4px 0;
    border-bottom: 1px dashed var(--glass-border);
}
.wiring-terminal {
    color: var(--text-secondary);
    text-transform: capitalize;
}
.wiring-pin {
    color: var(--primary-light);
    font-weight: 600;
}

.code-mode-toggle {
    display: flex;
    gap: 4px;
    padding: 4px;
    margin-bottom: var(--spacing-sm);
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    flex-shrink: 0;
}
.code-mode-btn {
    flex: 1;
    background: none;
    border: none;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    padding: 6px;
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition-fast);
}
.code-mode-btn:hover {
    color: var(--text-primary);
}
.code-mode-btn.active {
    background: var(--primary);
    color: #06210f;
}

.code-mode-panel:not(.active) {
    display: none !important;
}
.code-mode-panel.active {
    flex: 1;
    min-height: 0;
}

.code-editor {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-height: 0;
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    overflow: hidden;
    border: 1px solid var(--glass-border);
}
.editor-scroll {
    position: relative;
    flex: 1;
    min-height: 0;
}
.editor-highlight,
.editor-input {
    margin: 0;
    padding: var(--spacing-sm);
    font-family: "JetBrains Mono", "Fira Code", monospace;
    font-size: 0.82rem;
    line-height: 1.5;
    white-space: pre;
    tab-size: 2;
}
.editor-highlight {
    position: absolute;
    inset: 0;
    overflow: hidden;
    pointer-events: none;
    color: var(--text-primary);
}
.editor-input {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background: transparent;
    color: transparent;
    caret-color: var(--text-primary);
    border: none;
    outline: none;
    resize: none;
}
.editor-error {
    padding: 6px var(--spacing-sm);
    font-size: 0.75rem;
    color: var(--error);
    background: rgba(226, 33, 52, 0.08);
    display: none;
    border-top: 1px solid rgba(226, 33, 52, 0.3);
    flex-shrink: 0;
}
.editor-error.visible {
    display: block;
}

/* Block editor */
.block-editor {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    overflow-y: auto;
    padding-right: 2px;
}

.blocks-note {
    font-size: 0.72rem;
    color: var(--text-muted);
    font-style: italic;
    line-height: 1.4;
}

.block-section h4 {
    margin: 0 0 var(--spacing-sm);
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
}

.cat-pins {
    --cat: var(--cat-pins);
    --cat-shade: var(--cat-pins-dark);
}
.cat-sound {
    --cat: var(--cat-sound);
    --cat-shade: var(--cat-sound-dark);
}
.cat-control {
    --cat: var(--cat-control);
    --cat-shade: var(--cat-control-dark);
}
.cat-serial {
    --cat: var(--cat-serial);
    --cat-shade: var(--cat-serial-dark);
}
.cat-variables {
    --cat: var(--cat-variables);
    --cat-shade: var(--cat-variables-dark);
}
.cat-servo {
    --cat: var(--cat-servo);
    --cat-shade: var(--cat-servo-dark);
}

.block-list,
.block-mouth {
    display: flex;
    flex-direction: column;
    gap: 3px;
}
.block-list-hat {
    padding-left: 2px;
}
.block-mouth {
    margin: 2px 0 2px 22px;
    padding: 4px 0 4px 8px;
    border-left: 3px solid rgba(0, 0, 0, 0.25);
}

.block-card {
    position: relative;
    background: var(--cat, var(--bg-elevated));
    border-radius: 6px;
    border-bottom: 3px solid var(--cat-shade, var(--bg-tertiary));
    padding: 7px 10px 7px 10px;
    margin-left: 6px;
}
.block-card::before {
    content: "";
    position: absolute;
    top: -3px;
    left: 14px;
    width: 16px;
    height: 3px;
    background: inherit;
    border-radius: 3px 3px 0 0;
}

.block-hat {
    background: var(--cat-hat);
    border-bottom: 3px solid var(--cat-hat-dark);
    color: #3c2e00;
    font-weight: 700;
    font-size: 0.8rem;
    padding: 8px 12px;
    border-radius: 10px 10px 6px 6px;
    margin-bottom: -1px;
}

.block-forever {
    margin-left: 0;
}
.block-forever > .block-sentence .block-text {
    font-size: 0.82rem;
}

.block-cap-bar {
    height: 10px;
    width: 26px;
    margin-left: 6px;
    background: var(--cat, var(--bg-elevated));
    border-radius: 0 0 6px 6px;
    border-bottom: 3px solid var(--cat-shade, var(--bg-tertiary));
}

.block-sentence {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 5px;
    padding-right: 60px;
}
.block-text {
    color: #fff;
    font-weight: 700;
    font-size: 0.76rem;
    text-shadow: 0 1px 1px rgba(0, 0, 0, 0.15);
}

.block-controls {
    position: absolute;
    top: 4px;
    right: 6px;
    display: flex;
    gap: 2px;
}
.block-icon-btn {
    background: rgba(255, 255, 255, 0.25);
    border: none;
    color: #fff;
    border-radius: 50%;
    width: 16px;
    height: 16px;
    line-height: 16px;
    padding: 0;
    font-size: 0.6rem;
    cursor: pointer;
    transition: var(--transition-fast);
}
.block-icon-btn:hover {
    background: rgba(255, 255, 255, 0.45);
}

.field-pill {
    display: inline-flex;
}
.field-pill select,
.field-pill input {
    background: #fff;
    color: #17181a;
    border: none;
    border-radius: 10px;
    padding: 2px 8px;
    font-size: 0.74rem;
    font-weight: 600;
    min-width: 40px;
}
.field-pill select {
    cursor: pointer;
}
.field-pill-value {
    align-items: center;
}

.value-editor {
    display: inline-flex;
    flex-wrap: wrap;
    gap: 3px;
    align-items: center;
    background: rgba(0, 0, 0, 0.18);
    border-radius: 12px;
    padding: 2px;
}
.value-kind-select {
    min-width: 100px;
}
.value-sub-input {
    width: 56px;
}
.map-range {
    display: inline-flex;
    align-items: center;
    gap: 3px;
    font-size: 0.65rem;
    color: #fff;
    padding: 0 4px;
}
.map-num {
    width: 40px !important;
}

.block-branch-label {
    font-size: 0.68rem;
    font-weight: 700;
    color: var(--text-secondary);
    margin: 2px 0 2px 10px;
}

.block-palette {
    display: flex;
    flex-direction: column;
    gap: 4px;
    margin: 4px 0 2px 6px;
}
.palette-row {
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
}
.palette-chip {
    background: var(--cat, var(--bg-elevated));
    border: none;
    border-bottom: 2px solid var(--cat-shade, var(--bg-tertiary));
    color: #fff;
    font-weight: 700;
    font-size: 0.68rem;
    border-radius: 5px;
    padding: 4px 9px;
    cursor: pointer;
    transition: var(--transition-fast);
}
.palette-chip:hover {
    filter: brightness(1.1);
    transform: translateY(-1px);
}

.variable-row {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
    margin-bottom: var(--spacing-sm);
}
.variable-row .input:first-child {
    flex: 1;
}
.variable-row .input:nth-child(2) {
    width: 80px;
}

.serial-panel {
    display: flex;
    flex-direction: column;
    height: 180px;
    border-top: 1px solid var(--glass-border);
    background: var(--bg-tertiary);
    flex-shrink: 0;
}
.serial-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--glass-border);
}
.serial-header .btn {
    padding: 2px 10px;
    min-width: auto;
    font-size: 0.7rem;
}
.serial-output {
    flex: 1;
    margin: 0;
    padding: var(--spacing-sm);
    font-family: "JetBrains Mono", monospace;
    font-size: 0.78rem;
    color: var(--primary-light);
    overflow: auto;
    white-space: pre-wrap;
}

/* Lessons accordion: each lesson is its own collapsible section so students
   can browse/open several without losing their place, and progress on one
   lesson keeps ticking even while its section is collapsed. */
.lesson-select-wrap {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}
.lesson-select-wrap .label {
    margin-bottom: 0;
    white-space: nowrap;
}
.lesson-select {
    flex: 1;
    cursor: pointer;
}

.lesson-item {
    background: var(--bg-tertiary);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-sm);
    overflow: hidden;
}
.lesson-item.lesson-complete {
    border-color: rgba(29, 185, 84, 0.4);
}

.lesson-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    width: 100%;
    text-align: left;
    background: none;
    border: none;
    padding: var(--spacing-sm);
    color: var(--text-primary);
    transition: var(--transition-fast);
}
.lesson-header-static {
    cursor: default;
}
.lesson-header-text {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 2px;
    min-width: 0;
}
.lesson-header-text strong {
    font-size: 0.85rem;
}
.lesson-desc {
    font-size: 0.72rem;
    color: var(--text-secondary);
}
.lesson-done-badge {
    flex-shrink: 0;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--primary);
    color: #06210f;
    font-size: 0.68rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
}

.lesson-body {
    padding: 0 var(--spacing-sm) var(--spacing-sm);
    border-top: 1px solid var(--glass-border);
}
.lesson-body .steps-list {
    margin-top: var(--spacing-sm);
}

.steps-list {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    width: 100%;
}
.step-item {
    padding: var(--spacing-sm);
    border-radius: var(--radius-md);
    background: var(--bg-tertiary);
    border: 1px solid var(--glass-border);
    font-size: 0.8rem;
    opacity: 0.55;
}
.step-item.active {
    opacity: 1;
    border-color: var(--primary);
    box-shadow: 0 0 0 1px rgba(29, 185, 84, 0.2);
}
.step-item.done {
    opacity: 0.75;
}
.step-title {
    display: flex;
    align-items: center;
    gap: 6px;
    font-weight: 600;
}
.step-marker {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--bg-elevated);
    font-size: 0.68rem;
    flex-shrink: 0;
}
.step-item.done .step-marker {
    background: var(--primary);
    color: #000;
}
.step-desc {
    margin-top: 6px;
    color: var(--text-secondary);
}
.step-hint {
    margin-top: 6px;
    font-size: 0.72rem;
    color: var(--text-muted);
    font-style: italic;
}
.step-waiting {
    margin-top: 6px;
    font-size: 0.72rem;
    color: var(--text-muted);
}
.step-next {
    margin-top: var(--spacing-sm);
    background: var(--primary);
    color: #000;
    border: none;
    border-radius: var(--radius-sm);
    padding: 6px 12px;
    font-size: 0.75rem;
    font-weight: 700;
    cursor: pointer;
}