.lesson-board {
    margin: 1.8rem 0 2.4rem;
    padding: clamp(1rem, 3vw, 1.5rem);
    border: 1px solid #d9d4cb;
    background: #fbfaf7;
}

.lesson-board__header > span {
    color: #9b2730;
    font-size: 0.72rem;
    font-weight: 800;
    letter-spacing: 0.12em;
}

.lesson-board__title {
    margin: 0.35rem 0 0.45rem;
    color: #181a1e;
    font-size: clamp(1.35rem, 3vw, 1.85rem);
    font-weight: 800;
    letter-spacing: -0.045em;
    line-height: 1.3;
}

.lesson-board__header > p:last-child {
    margin: 0;
    color: #62666d;
    font-size: 0.95rem;
    line-height: 1.65;
}

.lesson-board__modes {
    display: grid;
    margin-top: 1.2rem;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.5rem;
}

.lesson-board__modes button.is-active {
    border-color: #2f6558;
    background: #2f6558;
    color: #fff;
}

.lesson-board__practice-guide {
    margin: 0.65rem 0 0;
    padding: 0.75rem 0.9rem;
    border-left: 4px solid #2f6558;
    background: #eef5f2;
    color: #34443f;
    font-size: 0.92rem;
    line-height: 1.6;
}

.lesson-board__examples {
    display: grid;
    margin: 1.2rem 0 0.8rem;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.5rem;
}

.lesson-board button {
    min-height: 2.8rem;
    padding: 0.65rem 0.8rem;
    border: 1px solid #c8c3ba;
    border-radius: 0;
    background: #fff;
    color: #30343a;
    font: inherit;
    font-size: 0.88rem;
    font-weight: 750;
    cursor: pointer;
}

.lesson-board button:hover,
.lesson-board button:focus-visible {
    border-color: #9b2730;
    outline: 2px solid rgba(155, 39, 48, 0.18);
    outline-offset: 2px;
}

.lesson-board__examples button.is-active {
    border-color: #9b2730;
    background: #9b2730;
    color: #fff;
}

.lesson-board__frame {
    width: 100%;
    max-width: 38rem;
    margin: 0 auto;
    border: 1px solid #80623d;
    background: #d7a763;
    box-shadow: 0 12px 30px rgba(54, 38, 20, 0.12);
}

.lesson-board__frame canvas {
    display: block;
    width: 100%;
    height: auto;
    aspect-ratio: 1;
}

.lesson-board__frame canvas.is-practice {
    cursor: crosshair;
    touch-action: manipulation;
}

.lesson-board__frame canvas.is-practice:focus-visible {
    outline: 4px solid rgba(47, 101, 88, 0.42);
    outline-offset: 3px;
}

.lesson-board__controls {
    display: grid;
    margin-top: 0.8rem;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 0.4rem;
}

.lesson-board__controls button:last-child {
    border-color: #2f6558;
    background: #2f6558;
    color: #fff;
}

.lesson-board__practice-controls {
    display: grid;
    margin-top: 0.8rem;
    grid-template-columns: minmax(0, 1fr) auto auto;
    gap: 0.5rem;
}

.lesson-board__practice-controls label {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    align-items: center;
    gap: 0.55rem;
    color: #3f454c;
    font-size: 0.86rem;
    font-weight: 750;
}

.lesson-board__practice-controls input {
    width: 100%;
    min-height: 2.8rem;
    padding: 0.55rem 0.7rem;
    border: 1px solid #c8c3ba;
    background: #fff;
    color: #181a1e;
    font: inherit;
    text-transform: uppercase;
}

.lesson-board__practice-controls input:focus-visible {
    border-color: #2f6558;
    outline: 2px solid rgba(47, 101, 88, 0.22);
    outline-offset: 2px;
}

.lesson-board__practice-controls button:not([data-lesson-practice-reset]) {
    border-color: #2f6558;
    background: #2f6558;
    color: #fff;
}

.lesson-board [hidden] {
    display: none !important;
}

.lesson-board__controls button:disabled {
    cursor: not-allowed;
    opacity: 0.42;
}

.lesson-board__status {
    margin-top: 0.8rem;
    padding: 0.9rem 1rem;
    border-left: 4px solid #9b2730;
    background: #fff;
}

.lesson-board__status strong,
.lesson-board__status p {
    display: block;
    margin: 0;
}

.lesson-board__status strong {
    color: #9b2730;
    font-size: 0.82rem;
}

.lesson-board__status p {
    margin-top: 0.3rem;
    color: #3f454c;
    font-size: 0.95rem;
    line-height: 1.65;
}

.lesson-board__transcript {
    margin-top: 0.8rem;
    border-top: 1px solid #d9d4cb;
}

.lesson-board__transcript summary {
    padding: 0.9rem 0 0.1rem;
    color: #30343a;
    font-size: 0.9rem;
    font-weight: 750;
    cursor: pointer;
}

.lesson-board__transcript section {
    padding-top: 0.6rem;
}

.lesson-board__transcript h3 {
    margin: 0.8rem 0 0.45rem;
    font-size: 1rem;
}

.lesson-board__transcript ol,
.lesson-board__transcript p {
    margin: 0.5rem 0 0;
    color: #50555c;
    font-size: 0.88rem;
    line-height: 1.7;
}

@media (max-width: 600px) {
    .lesson-board {
        margin-right: 0;
        margin-left: 0;
        padding: 0.85rem;
    }

    .lesson-board__controls {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .lesson-board__modes {
        position: sticky;
        z-index: 2;
        top: 0;
        background: #fbfaf7;
    }

    .lesson-board__practice-controls {
        grid-template-columns: 1fr 1fr;
    }

    .lesson-board__practice-controls label {
        grid-column: 1 / -1;
    }

    .lesson-board button {
        min-height: 3rem;
        font-size: 0.84rem;
    }
}

@media (prefers-reduced-motion: reduce) {
    .lesson-board button {
        scroll-behavior: auto;
    }
}