/* Canonical Cube Trains workspace; shared aliases keep Math and English on the same rules. */
:is(.cube_addition_training, .trainer-training) {
    --cube-addition-size: 76px;
    align-items: center;
    overflow-y: auto;
    color: var(--main);
}

:is(.cube_addition_content, .trainer-content) {
    width: 100%;
    max-width: 920px;
    margin: auto;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    gap: 18px;
}

:is(.cube_addition_prompt, .trainer-prompt) {
    width: 100%;
    min-height: 50px;
    display: flex;
    align-items: center;
    gap: 14px;
}

:is(.cube_addition_speaker, .trainer-speaker) {
    width: 46px;
    height: 46px;
    min-width: 46px;
    padding: 0;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 0;
    border-radius: 50%;
    background: rgba(0, 174, 255, 0.1);
    cursor: pointer;
    transition: background-color 0.15s ease, transform 0.15s ease;
}

:is(.cube_addition_speaker, .trainer-speaker):hover {
    background: rgba(0, 174, 255, 0.17);
    transform: translateY(-1px);
}

:is(.cube_addition_speaker, .trainer-speaker):focus-visible {
    outline: 3px solid var(--blue3);
    outline-offset: 3px;
}

:is(.cube_addition_speaker, .trainer-speaker) svg {
    width: 28px;
    height: 23px;
    display: block;
}

:is(.cube_addition_instruction, .trainer-instruction) {
    margin: 0;
    color: var(--main);
    font-size: 23px;
    line-height: 1.35;
    font-weight: var(--main_bold_weight);
}

:is(.cube_addition_instruction, .trainer-instruction) strong {
    color: var(--cube-number-color, var(--blue3));
    font-size: 1.15em;
    font-weight: var(--main_boldest_weight);
}

:is(.cube_addition_frame, .trainer-frame) {
    width: 100%;
    min-height: 176px;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 30px 24px 22px;
    box-sizing: border-box;
    border: 3px dashed var(--lightgray);
    border-bottom-width: 5px;
    border-radius: 14px;
    background:
        radial-gradient(circle at 18% 18%, rgba(28, 85, 229, 0.07), transparent 32%),
        linear-gradient(180deg, rgba(50, 191, 76, 0.035), rgba(28, 85, 229, 0.025)),
        var(--white);
    transition: border-color 0.15s ease, background-color 0.15s ease, box-shadow 0.15s ease;
}

:is(.cube_addition_frame, .trainer-frame).is_drag_over {
    border-color: var(--blue3);
    background-color: rgba(28, 85, 229, 0.07);
    box-shadow: inset 0 0 0 4px rgba(28, 85, 229, 0.08);
}

:is(.cube_addition_frame, .trainer-frame).is_correct {
    border-color: var(--green);
    box-shadow: inset 0 0 0 4px rgba(50, 191, 76, 0.08);
}

:is(.cube_addition_frame, .trainer-frame).is_wrong {
    border-color: var(--red);
    box-shadow: inset 0 0 0 4px rgba(246, 81, 29, 0.07);
}

.cube_addition_frame_count {
    min-width: 74px;
    position: absolute;
    top: 10px;
    right: 12px;
    z-index: 4;
    display: none;
    padding: 5px 10px;
    border-radius: 999px;
    background: var(--white);
    color: var(--secondary);
    box-shadow: 0 2px 8px rgba(32, 33, 36, 0.1);
    font-size: 15px;
    line-height: 1;
    font-weight: var(--main_bolder_weight);
    text-align: center;
}

:is(.cube_addition_frame, .trainer-frame).show_help .cube_addition_frame_count {
    display: block;
}

.cube_addition_cubes {
    min-height: var(--cube-addition-size);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 4px;
    filter: drop-shadow(0 7px 5px rgba(32, 33, 36, 0.12));
}

.cube_addition_cube {
    width: var(--cube-addition-size);
    height: var(--cube-addition-size);
    min-width: var(--cube-addition-size);
    min-height: var(--cube-addition-size);
    position: relative;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    box-sizing: border-box;
    padding: 0;
    border: 4px solid var(--cube-dark);
    border-bottom-width: 7px;
    border-radius: 13px;
    background:
        linear-gradient(180deg, var(--cube-light) 0 5px, transparent 5px),
        linear-gradient(145deg, var(--cube-light) 0%, var(--cube) 24%, var(--cube) 100%);
    box-shadow:
        inset 0 2px 0 rgba(255, 255, 255, 0.36),
        inset 0 -4px 0 rgba(0, 0, 0, 0.06);
    color: var(--main);
    user-select: none;
    -webkit-tap-highlight-color: transparent;
    transition: transform 0.12s ease, opacity 0.12s ease, box-shadow 0.12s ease;
}

button.cube_addition_cube {
    cursor: grab;
    touch-action: none;
}

button.cube_addition_cube:hover,
button.cube_addition_cube:focus-visible {
    outline: none;
    transform: translateY(-2px);
    box-shadow:
        0 0 0 4px rgba(28, 85, 229, 0.16),
        inset 0 2px 0 rgba(255, 255, 255, 0.36),
        inset 0 -4px 0 rgba(0, 0, 0, 0.06);
}

button.cube_addition_cube:active {
    cursor: grabbing;
}

.cube_addition_cube::after {
    content: "";
    width: 51%;
    height: 51%;
    position: relative;
    z-index: 2;
    display: block;
    box-sizing: border-box;
    border: 3px solid rgba(255, 255, 255, 0.4);
    border-radius: 50%;
    background:
        radial-gradient(circle at 35% 30%, rgba(255, 255, 255, 0.42) 0 11%, transparent 12%),
        linear-gradient(145deg, var(--cube), var(--cube-dark));
    box-shadow:
        inset 0 5px 7px rgba(0, 0, 0, 0.15),
        0 2px 0 rgba(255, 255, 255, 0.28);
}

.cube_addition_cube.group_start {
    margin-left: 15px;
}

.cube_addition_cube.group_start::before,
.cube_addition_hint_cube.group_start::before {
    content: "+";
    width: 25px;
    height: 25px;
    position: absolute;
    top: -24px;
    left: -22px;
    z-index: 4;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--blue_border);
    border-radius: 50%;
    background: var(--white);
    color: var(--blue3);
    box-shadow: 0 2px 5px rgba(32, 33, 36, 0.1);
    font-size: 19px;
    line-height: 1;
    font-weight: var(--main_boldest_weight);
}

.cube_addition_cube.is_added {
    animation: cube_addition_pop 0.22s ease-out both;
}

.cube_addition_cube.is_extra {
    box-shadow:
        0 0 0 5px rgba(246, 81, 29, 0.22),
        inset 0 2px 0 rgba(255, 255, 255, 0.36);
}

.cube_addition_hint_cube {
    width: var(--cube-addition-size);
    height: var(--cube-addition-size);
    min-width: var(--cube-addition-size);
    min-height: var(--cube-addition-size);
    position: relative;
    box-sizing: border-box;
    border: 3px dashed var(--cube);
    border-radius: 13px;
    background: var(--cube-soft);
    opacity: 0.42;
}

.cube_addition_source_area {
    width: 100%;
    min-height: 102px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 7px 16px;
    box-sizing: border-box;
}

.cube_addition_source_wrap {
    position: relative;
    padding: 8px;
}

.cube_addition_source_wrap::after {
    content: "+";
    width: 27px;
    height: 27px;
    position: absolute;
    right: 0;
    bottom: 2px;
    z-index: 5;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 3px solid var(--white);
    border-radius: 50%;
    background: var(--blue3);
    color: #fff;
    box-shadow: 0 2px 6px rgba(28, 85, 229, 0.28);
    font-size: 20px;
    font-weight: var(--main_boldest_weight);
    pointer-events: none;
}

.cube_addition_source_wrap.help_glow {
    animation: cube_addition_pulse 1s ease-in-out infinite;
}

.cube_addition_text {
    margin: 0;
    color: var(--main);
    font-size: 25px;
    line-height: 1.35;
    font-weight: var(--main_bold_weight);
}

.cube_addition_question {
    margin-top: 2px;
}

.cube_addition_equation_row {
    width: 100%;
    min-height: 70px;
    display: flex;
    align-items: center;
    gap: 14px;
}

.cube_addition_equation {
    display: flex;
    align-items: center;
    gap: 13px;
    color: var(--main);
    font-size: 35px;
    line-height: 1;
    font-weight: var(--main_bolder_weight);
    font-variant-numeric: tabular-nums;
}

.cube_addition_operator {
    color: var(--secondary);
}

.cube_addition_result {
    width: 70px;
    height: 60px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 3px solid var(--blue_border);
    border-bottom-width: 5px;
    border-radius: 10px;
    background: var(--white);
    color: var(--main);
    text-align: center;
    transition: border-color 0.15s ease, box-shadow 0.15s ease, background-color 0.15s ease, color 0.15s ease;
}

.cube_addition_result.is_correct {
    border-color: var(--green);
    background: rgba(50, 191, 76, 0.07);
    color: var(--green);
    box-shadow: 0 0 0 4px rgba(50, 191, 76, 0.1);
}

.cube_addition_result.is_wrong {
    border-color: var(--red);
    background: rgba(246, 81, 29, 0.05);
    color: var(--red);
    box-shadow: 0 0 0 4px rgba(246, 81, 29, 0.1);
    animation: cube_addition_shake 0.24s ease;
}

.cube_addition_answers {
    width: 100%;
    max-width: 760px;
    padding-left: 60px;
    display: grid;
    grid-template-columns: repeat(10, minmax(0, 1fr));
    gap: 8px;
    box-sizing: border-box;
}

:is(.cube_addition_answer, .trainer-answer) {
    min-width: 0;
    min-height: 58px;
    padding: 8px;
    border: var(--border);
    border-bottom-width: 4px;
    border-radius: 9px;
    background: var(--white);
    color: var(--main);
    font-family: var(--main_font);
    font-size: 29px;
    line-height: 1;
    font-weight: var(--main_bolder_weight);
    font-variant-numeric: tabular-nums;
    cursor: pointer;
    transition: transform 0.12s ease, border-color 0.12s ease, color 0.12s ease, background-color 0.12s ease, box-shadow 0.12s ease;
}

:is(.cube_addition_answer, .trainer-answer):not(:disabled):focus-visible {
    border-color: var(--blue3);
    outline: 3px solid rgba(0, 174, 255, 0.24);
    outline-offset: 2px;
    transform: translateY(-1px);
}

@media (hover: hover) {
    :is(.cube_addition_answer, .trainer-answer):not(:disabled):hover {
        border-color: var(--blue3);
        color: var(--blue3);
        transform: translateY(-1px);
    }
}

:is(.cube_addition_answer, .trainer-answer).is_correct {
    border-color: var(--green);
    background: rgba(50, 191, 76, 0.08);
    color: var(--green);
    box-shadow: 0 0 0 3px rgba(50, 191, 76, 0.1);
}

:is(.cube_addition_answer, .trainer-answer).is_wrong {
    border-color: var(--red);
    background: rgba(246, 81, 29, 0.07);
    color: var(--red);
    box-shadow: 0 0 0 3px rgba(246, 81, 29, 0.08);
    animation: cube_addition_shake 0.24s ease;
}

:is(.cube_addition_feedback, .trainer-feedback) {
    min-height: 28px;
    padding-left: 60px;
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--main);
    font-size: 18px;
    line-height: 1.3;
    font-weight: var(--main_bolder_weight);
}

.cube_addition_feedback_text {
    min-width: 0;
}

.cube_addition_feedback_speaker {
    width: 30px;
    height: 30px;
    min-width: 30px;
    padding: 0;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 0;
    border-radius: 50%;
    background: rgba(0, 174, 255, 0.1);
    cursor: pointer;
}

.cube_addition_feedback_speaker:focus-visible {
    outline: 3px solid var(--blue3);
    outline-offset: 2px;
}

.cube_addition_feedback_speaker svg {
    width: 20px;
    height: 17px;
}

:is(.cube_addition_feedback, .trainer-feedback).success {
    color: var(--green);
}

:is(.cube_addition_feedback, .trainer-feedback).error {
    color: var(--red);
}

:is(.cube_addition_actions, .trainer-actions) {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

:is(.cube_addition_actions, .trainer-actions) .btn {
    width: 160px;
    min-width: 0;
    min-height: 52px;
    flex: 0 1 160px;
    font-size: 17px;
}

.cube_addition_check:disabled {
    transform: none;
}

.cube_addition_help:focus-visible {
    outline: 3px solid var(--blue3);
    outline-offset: 4px;
}

.cube_addition_help[aria-pressed="true"] {
    box-shadow: 0 0 0 4px rgba(0, 174, 255, 0.12);
}

.cube_addition_drag_clone {
    position: fixed !important;
    left: 0;
    top: 0;
    z-index: 10000;
    margin: 0 !important;
    pointer-events: none;
    opacity: 0.96;
    transform: translate(-50%, -50%) scale(1.08);
    filter: drop-shadow(0 10px 7px rgba(32, 33, 36, 0.2));
}

.cube_addition_cube.drag_origin {
    opacity: 0.34;
    transform: scale(0.94);
}

.cube_addition_locked .cube_addition_cube,
.cube_addition_locked :is(.cube_addition_answer, .trainer-answer),
.cube_addition_locked :is(.cube_addition_speaker, .trainer-speaker),
.cube_addition_locked .cube_addition_feedback_speaker,
.cube_addition_locked .cube_addition_check,
.cube_addition_locked .cube_addition_help {
    pointer-events: none;
}

.cube_addition_sr_only {
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    position: absolute;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

@keyframes cube_addition_pop {
    from {
        opacity: 0;
        transform: translateY(8px) scale(0.92);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

@keyframes cube_addition_pulse {
    0%,
    100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.06);
    }
}

@keyframes cube_addition_shake {
    0%,
    100% {
        transform: translateX(0);
    }
    33% {
        transform: translateX(-4px);
    }
    66% {
        transform: translateX(4px);
    }
}

@media (max-width: 820px) {
    :is(.cube_addition_training, .trainer-training) {
        --cube-addition-size: 66px;
    }

    :is(.cube_addition_content, .trainer-content) {
        max-width: 680px;
        gap: 15px;
    }

    :is(.cube_addition_instruction, .trainer-instruction) {
        font-size: 20px;
    }

    .cube_addition_text {
        font-size: 22px;
    }

    :is(.cube_addition_frame, .trainer-frame) {
        min-height: 154px;
    }

    :is(.cube_addition_frame, .trainer-frame).is_two_rows {
        min-height: 205px;
    }

    .cube_addition_cubes.is_two_rows {
        display: grid;
        grid-template-columns: repeat(5, var(--cube-addition-size));
        gap: 8px 4px;
    }

    .cube_addition_cubes.is_two_rows .cube_addition_cube.group_start,
    .cube_addition_cubes.is_two_rows .cube_addition_hint_cube.group_start {
        margin-left: 0;
    }

    .cube_addition_cube {
        border-width: 3px;
        border-bottom-width: 6px;
        border-radius: 11px;
    }

    .cube_addition_source_area {
        min-height: 94px;
    }

    .cube_addition_equation {
        font-size: 31px;
    }

    .cube_addition_result {
        width: 64px;
        height: 56px;
    }

    .cube_addition_answers {
        max-width: 500px;
        grid-template-columns: repeat(5, minmax(0, 1fr));
    }
}

@media (max-width: 520px) {
    :is(.cube_addition_training, .trainer-training) {
        --cube-addition-size: 50px;
        justify-content: flex-start;
        padding: 18px 14px 16px;
    }

    :is(.cube_addition_content, .trainer-content) {
        margin: 0 auto;
        gap: 13px;
    }

    :is(.cube_addition_prompt, .trainer-prompt),
    .cube_addition_equation_row {
        gap: 9px;
    }

    :is(.cube_addition_speaker, .trainer-speaker) {
        width: 38px;
        height: 38px;
        min-width: 38px;
    }

    :is(.cube_addition_speaker, .trainer-speaker) svg {
        width: 23px;
        height: 20px;
    }

    :is(.cube_addition_instruction, .trainer-instruction) {
        font-size: 17px;
        line-height: 1.3;
    }

    .cube_addition_text {
        font-size: 18px;
        line-height: 1.3;
    }

    :is(.cube_addition_frame, .trainer-frame) {
        min-height: 118px;
        padding: 26px 7px 14px;
        border-width: 2px;
        border-bottom-width: 4px;
        border-radius: 11px;
    }

    :is(.cube_addition_frame, .trainer-frame).is_two_rows {
        min-height: 160px;
    }

    .cube_addition_cubes {
        gap: 3px;
    }

    .cube_addition_cubes.is_two_rows {
        gap: 6px 3px;
    }

    .cube_addition_cube {
        border-width: 2px;
        border-bottom-width: 5px;
        border-radius: 9px;
    }

    .cube_addition_cube::after {
        border-width: 2px;
    }

    .cube_addition_cube.group_start {
        margin-left: 11px;
    }

    .cube_addition_cube.group_start::before,
    .cube_addition_hint_cube.group_start::before {
        width: 21px;
        height: 21px;
        top: -21px;
        left: -17px;
        font-size: 16px;
    }

    .cube_addition_hint_cube {
        border-width: 2px;
        border-radius: 9px;
    }

    .cube_addition_frame_count {
        top: 5px;
        right: 6px;
        min-width: 62px;
        padding: 4px 7px;
        font-size: 13px;
    }

    .cube_addition_source_area {
        min-height: 78px;
        padding: 2px 4px;
    }

    .cube_addition_source_wrap {
        padding: 5px;
    }

    .cube_addition_source_wrap::after {
        width: 23px;
        height: 23px;
        right: -1px;
        bottom: 0;
        border-width: 2px;
        font-size: 17px;
    }

    .cube_addition_equation_row {
        min-height: 58px;
    }

    .cube_addition_equation {
        gap: 9px;
        font-size: 27px;
    }

    .cube_addition_result {
        width: 58px;
        height: 52px;
        border-width: 2px;
        border-bottom-width: 4px;
        border-radius: 8px;
    }

    .cube_addition_answers {
        padding-left: 47px;
        gap: 6px;
    }

    :is(.cube_addition_answer, .trainer-answer) {
        min-height: 50px;
        padding: 5px 2px;
        border-bottom-width: 4px;
        border-radius: 8px;
        font-size: 25px;
    }

    :is(.cube_addition_feedback, .trainer-feedback) {
        min-height: 24px;
        font-size: 16px;
    }

    :is(.cube_addition_feedback, .trainer-feedback) {
        padding-left: 47px;
    }

    :is(.cube_addition_actions, .trainer-actions) .btn {
        min-height: 50px;
        font-size: 16px;
    }
}

@media (max-width: 360px) {
    :is(.cube_addition_training, .trainer-training) {
        --cube-addition-size: 45px;
    }

    :is(.cube_addition_frame, .trainer-frame).is_two_rows {
        min-height: 150px;
    }

    :is(.cube_addition_instruction, .trainer-instruction) {
        font-size: 16px;
    }

    .cube_addition_text {
        font-size: 17px;
    }

    .cube_addition_equation {
        font-size: 25px;
    }

}

@media (prefers-reduced-motion: reduce) {
    .cube_addition_cube,
    .cube_addition_result,
    :is(.cube_addition_answer, .trainer-answer),
    :is(.cube_addition_speaker, .trainer-speaker),
    .cube_addition_source_wrap {
        animation: none !important;
        transition: none !important;
    }
}

/* Sessions without scoring end at their content, including their completion state. */
.practice-only .main_wrapper,.practice-only .training_wrapper { min-height:0; }
.practice-only .trainer-content { margin:0 auto; }

/* Keep the responsive shell steady when feedback adds a vertical scrollbar. */
html:has(.practice-only) { scrollbar-gutter:stable; }