:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) {
    --ch18-ink: #17333d;
    --ch18-muted: #60757d;
    --ch18-line: #78929a;
    --ch18-grid: #d8e3e8;
    --ch18-surface: #f2f7fb;
    --ch18-primary: #0b7189;
    --ch18-secondary: #c55f2e;
    --ch18-tertiary: #6b57a2;
    margin: clamp(1.1rem, 2.6vw, 1.8rem) 0;
    padding: clamp(1rem, 2.6vw, 1.45rem);
    border: 1px solid color-mix(in srgb, var(--ch18-primary) 18%, transparent);
    border-radius: 1.25rem;
    background: linear-gradient(145deg, #fbfdff 0%, var(--ch18-surface) 100%);
    color: var(--ch18-ink);
    box-shadow: 0 0.8rem 2rem rgb(23 51 61 / 0.07);
    overflow: clip;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-heading {
    display: grid;
    gap: 0.2rem;
    margin-bottom: 0.9rem;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-heading h3 {
    margin: 0;
    font-size: var(--unit-text-heading-medium, 17px);
    line-height: 1.18;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-kicker {
    margin: 0;
    color: var(--ch18-primary);
    font-size: var(--unit-text-micro, 11px);
    font-weight: 800;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-controls {
    display: grid;
    grid-template-columns: repeat(var(--ch18-control-count, 4), minmax(0, 1fr));
    gap: 0.45rem;
    margin-bottom: 0.85rem;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-control {
    height: 41px;
    min-width: 0;
    padding: 0.48rem 0.42rem;
    border: 1px solid color-mix(in srgb, var(--ch18-line) 65%, transparent);
    border-radius: 0.72rem;
    background: rgb(255 255 255 / 0.88);
    color: var(--ch18-ink);
    font: inherit;
    font-size: var(--unit-text-meta, 12px);
    font-weight: 750;
    line-height: 1;
    white-space: nowrap;
    text-overflow: ellipsis;
    overflow: hidden;
    cursor: pointer;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-control:is(:hover, :focus-visible) {
    border-color: var(--ch18-primary);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-control[aria-pressed="true"] {
    border-color: var(--ch18-primary);
    background: var(--ch18-primary);
    color: #fff;
    box-shadow: 0 0.35rem 0.9rem rgb(11 113 137 / 0.22);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) :is(.ch18-visual-stage, .ch18-visual-panel) {
    min-width: 0;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-panel[hidden] {
    display: none !important;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-drawing {
    position: relative;
    width: 100%;
    aspect-ratio: var(--ch18-drawing-ratio, 720 / 360);
    border-radius: 0.95rem;
    background: rgb(255 255 255 / 0.82);
    container-type: inline-size;
    overflow: clip;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-drawing > svg {
    position: absolute;
    inset: 0;
    display: block;
    width: 100%;
    height: 100%;
    max-height: none;
    border-radius: inherit;
    overflow: visible;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-math-label {
    position: absolute;
    z-index: 3;
    max-width: 46%;
    color: var(--ch18-ink);
    font-size: clamp(0.65rem, 2.25cqw, 1rem);
    font-weight: 650;
    line-height: 1;
    white-space: nowrap;
    pointer-events: none;
    transform: translate(-50%, -50%);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-math-label[data-math-anchor="start"] {
    transform: translate(0, -50%);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-math-label[data-math-anchor="end"] {
    transform: translate(-100%, -50%);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-math-label :is(mjx-container, mjx-container[display="true"]) {
    max-width: 100%;
    margin: 0 !important;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-math-label.is-emphasis {
    font-size: clamp(0.76rem, 3cqw, 1.18rem);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-math-label.is-equation {
    max-width: 74%;
    font-size: clamp(0.7rem, 2.65cqw, 1.05rem);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-math-label.is-small {
    font-size: clamp(0.55rem, 1.8cqw, 0.79rem);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-math-label.is-charge {
    max-width: 12%;
    color: #fff;
    font-size: clamp(0.58rem, 1.9cqw, 0.82rem);
    font-weight: 800;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-math-label.is-plate {
    font-size: clamp(0.8rem, 3.2cqw, 1.25rem);
    font-weight: 850;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-visual-caption {
    min-height: 2.8em;
    margin: 0.7rem 0 0;
    color: var(--ch18-muted);
    font-size: var(--unit-text-detail, 14px);
    line-height: 1.42;
}

:is(
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="potential_work_path"]
) .ch18-motion-timeline {
    display: grid;
    gap: 0.55rem;
    min-width: 0;
}

:is(
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="potential_work_path"]
) .ch18-motion-controls {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr) 2.7rem;
    align-items: center;
    gap: 0.55rem;
    min-width: 0;
}

:is(
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="potential_work_path"]
) .ch18-motion-play {
    min-width: 5rem;
    min-height: 2.2rem;
    padding: 0.4rem 0.62rem;
    border: 1px solid var(--ch18-primary);
    border-radius: 0.68rem;
    background: var(--ch18-primary);
    color: #fff;
    font: inherit;
    font-size: var(--unit-text-meta, 12px);
    font-weight: 780;
    line-height: 1;
    white-space: nowrap;
    cursor: pointer;
}

:is(
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="potential_work_path"]
) .ch18-motion-play:is(:hover, :focus-visible) {
    background: color-mix(in srgb, var(--ch18-primary) 84%, #000);
}

:is(
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="potential_work_path"]
) .ch18-motion-range {
    width: 100%;
    min-width: 0;
    accent-color: var(--ch18-primary);
}

:is(
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="potential_work_path"]
) .ch18-motion-output {
    color: var(--ch18-muted);
    font-size: var(--unit-text-meta, 12px);
    font-variant-numeric: tabular-nums;
    text-align: right;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) :is(.ch18-axis, .ch18-track) {
    fill: none;
    stroke: var(--ch18-line);
    stroke-width: 1.35;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) :is(.ch18-field-line, .ch18-vector, .ch18-curve, .ch18-trajectory, .ch18-path-guide, .ch18-tangent) {
    fill: none;
    vector-effect: non-scaling-stroke;
    stroke-linecap: round;
    stroke-linejoin: round;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) :is(.ch18-field-line, .ch18-vector.is-primary, .ch18-curve.is-primary) {
    stroke: var(--ch18-primary);
    stroke-width: 2.25;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) :is(.ch18-vector.is-secondary, .ch18-curve.is-secondary) {
    stroke: var(--ch18-secondary);
    stroke-width: 2.35;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) :is(.ch18-vector.is-tertiary, .ch18-path-guide) {
    stroke: var(--ch18-tertiary);
    stroke-width: 2.15;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-trajectory.is-progress {
    stroke: var(--ch18-secondary);
    stroke-width: 2.45;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-trajectory.is-guide {
    stroke: color-mix(in srgb, var(--ch18-secondary) 38%, #fff);
    stroke-width: 1.3;
    stroke-dasharray: 7 7;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-tangent {
    stroke: var(--ch18-tertiary);
    stroke-width: 1.8;
    stroke-dasharray: 7 6;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) :is(.ch18-construction, .ch18-path-guide) {
    fill: none;
    stroke: var(--ch18-line);
    stroke-width: 1.25;
    vector-effect: non-scaling-stroke;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) :is(.ch18-construction.is-dashed, .ch18-path-guide) {
    stroke-dasharray: 6 6;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-field-line.is-edge {
    stroke: color-mix(in srgb, var(--ch18-primary) 66%, #fff);
    stroke-width: 1.65;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-charge {
    stroke: #fff;
    stroke-width: 2;
    vector-effect: non-scaling-stroke;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-charge:is(.is-positive, .is-probe) {
    fill: var(--ch18-primary);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-charge.is-negative {
    fill: var(--ch18-secondary);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) :is(.ch18-point, .ch18-sample-point, .ch18-centre-point, .ch18-zero-point, .ch18-selected-point) {
    fill: var(--ch18-ink);
    stroke: #fff;
    stroke-width: 1.2;
    vector-effect: non-scaling-stroke;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-conductor {
    fill: color-mix(in srgb, var(--ch18-primary) 10%, #fff);
    stroke: var(--ch18-primary);
    stroke-width: 2;
    vector-effect: non-scaling-stroke;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-plate {
    stroke-width: 5;
    stroke-linecap: round;
    vector-effect: non-scaling-stroke;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-plate.is-positive {
    stroke: var(--ch18-primary);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-plate.is-negative {
    stroke: var(--ch18-secondary);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-arrowhead {
    fill: none;
    stroke-width: 1.8;
    stroke-linecap: round;
    stroke-linejoin: round;
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-arrowhead.is-primary {
    stroke: var(--ch18-primary);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-arrowhead.is-secondary {
    stroke: var(--ch18-secondary);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-arrowhead.is-tertiary {
    stroke: var(--ch18-tertiary);
}

:is(
    [data-unit-visual-extension="field_source_test_charge"],
    [data-unit-visual-extension="electric_field_lines"],
    [data-unit-visual-extension="uniform_plate_field"],
    [data-unit-visual-extension="charged_particle_motion"],
    [data-unit-visual-extension="coulomb_force_pair"],
    [data-unit-visual-extension="point_charge_field"],
    [data-unit-visual-extension="potential_work_path"],
    [data-unit-visual-extension="point_charge_potential_energy"],
    [data-unit-visual-extension="potential_gradient"]
) .ch18-small-label {
    fill: var(--ch18-muted);
    font-family: inherit;
    font-size: 18px;
    font-weight: 650;
}

@media (max-width: 620px) {
    :is(
        [data-unit-visual-extension="field_source_test_charge"],
        [data-unit-visual-extension="electric_field_lines"],
        [data-unit-visual-extension="uniform_plate_field"],
        [data-unit-visual-extension="charged_particle_motion"],
        [data-unit-visual-extension="coulomb_force_pair"],
        [data-unit-visual-extension="point_charge_field"],
        [data-unit-visual-extension="potential_work_path"],
        [data-unit-visual-extension="point_charge_potential_energy"],
        [data-unit-visual-extension="potential_gradient"]
    ) {
        padding: 0.82rem;
    }

    :is(
        [data-unit-visual-extension="field_source_test_charge"],
        [data-unit-visual-extension="electric_field_lines"],
        [data-unit-visual-extension="uniform_plate_field"],
        [data-unit-visual-extension="charged_particle_motion"],
        [data-unit-visual-extension="coulomb_force_pair"],
        [data-unit-visual-extension="point_charge_field"],
        [data-unit-visual-extension="potential_work_path"],
        [data-unit-visual-extension="point_charge_potential_energy"],
        [data-unit-visual-extension="potential_gradient"]
    ) .ch18-visual-controls {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    :is(
        [data-unit-visual-extension="field_source_test_charge"],
        [data-unit-visual-extension="electric_field_lines"],
        [data-unit-visual-extension="uniform_plate_field"],
        [data-unit-visual-extension="charged_particle_motion"],
        [data-unit-visual-extension="coulomb_force_pair"],
        [data-unit-visual-extension="point_charge_field"],
        [data-unit-visual-extension="potential_work_path"],
        [data-unit-visual-extension="point_charge_potential_energy"],
        [data-unit-visual-extension="potential_gradient"]
    ) .ch18-visual-control {
        height: 40px;
        padding-inline: 0.35rem;
    }

    :is(
        [data-unit-visual-extension="field_source_test_charge"],
        [data-unit-visual-extension="electric_field_lines"],
        [data-unit-visual-extension="uniform_plate_field"],
        [data-unit-visual-extension="charged_particle_motion"],
        [data-unit-visual-extension="coulomb_force_pair"],
        [data-unit-visual-extension="point_charge_field"],
        [data-unit-visual-extension="potential_work_path"],
        [data-unit-visual-extension="point_charge_potential_energy"],
        [data-unit-visual-extension="potential_gradient"]
    ) .ch18-small-label {
        font-size: 20px;
    }

    :is(
        [data-unit-visual-extension="charged_particle_motion"],
        [data-unit-visual-extension="potential_work_path"]
    ) .ch18-motion-controls {
        grid-template-columns: auto minmax(0, 1fr) 2.7rem;
        gap: 0.42rem;
    }

    :is(
        [data-unit-visual-extension="charged_particle_motion"],
        [data-unit-visual-extension="potential_work_path"]
    ) .ch18-motion-play {
        min-width: 4.7rem;
        min-height: 2.1rem;
        padding-inline: 0.5rem;
    }
}

@media (prefers-reduced-motion: reduce) {
    :is(
        [data-unit-visual-extension="field_source_test_charge"],
        [data-unit-visual-extension="electric_field_lines"],
        [data-unit-visual-extension="uniform_plate_field"],
        [data-unit-visual-extension="charged_particle_motion"],
        [data-unit-visual-extension="coulomb_force_pair"],
        [data-unit-visual-extension="point_charge_field"],
        [data-unit-visual-extension="potential_work_path"],
        [data-unit-visual-extension="point_charge_potential_energy"],
        [data-unit-visual-extension="potential_gradient"]
    ) * {
        scroll-behavior: auto !important;
        transition-duration: 0.01ms !important;
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
    }
}