@media (max-width: 900px) {
    .hero {
        grid-template-columns: 1fr;
        gap: 18px;
        padding: 40px;
    }

    .hero__art {
        min-height: 210px;
    }

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

@media (max-width: 640px) {
    .site-header,
    #app-content,
    .site-footer {
        width: min(calc(100% - 24px), var(--content-width));
    }

    .site-header {
        min-height: 70px;
        margin-top: 10px;
        padding: 10px 12px;
        border-radius: 18px;
    }

    .brand__mark {
        width: 46px;
        height: 46px;
        border-radius: 14px;
    }

    .brand__copy strong {
        font-size: 0.95rem;
    }

    .brand__copy span {
        font-size: 0.8rem;
    }

    .icon-button {
        width: 46px;
        height: 46px;
    }

    .hero {
        min-height: 0;
        margin-top: 24px;
        padding: 30px 24px;
        border-radius: 22px;
    }

    .hero h1 {
        font-size: clamp(2.15rem, 13vw, 3.3rem);
    }

    .letter-stack {
        width: 190px;
        height: 205px;
    }

    .letter-stack img {
        width: 122px;
        height: 160px;
    }

    .section-heading {
        display: block;
        margin-top: 38px;
    }

    .section-heading p {
        margin-top: 8px;
    }

    .game-grid {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .progress-strip {
        grid-template-columns: 1fr;
        gap: 10px;
    }

    .progress-strip > div {
        min-height: 68px;
    }

    .game-card {
        min-height: 250px;
        padding: 22px;
    }

    .game-intro {
        margin-top: 24px;
        padding: 26px 22px;
        border-radius: 22px;
    }

    .game-intro__top {
        display: block;
    }

    .game-intro__icon {
        width: 72px;
        height: 72px;
        margin-bottom: 18px;
        font-size: 2.2rem;
    }

    .game-intro__panel {
        grid-template-columns: 1fr;
    }

    .difficulty-control {
        align-items: stretch;
        flex-direction: column;
    }

    .difficulty-control select {
        width: 100%;
    }

    .play-shell {
        margin-top: 24px;
        padding: 22px 16px;
        border-radius: 22px;
    }

    .play-heading {
        align-items: flex-start;
    }

    .play-heading .button {
        min-width: 48px;
        padding-inline: 12px;
    }

    .session-status {
        gap: 12px;
        padding: 12px;
    }

    .shuffle-stage {
        min-height: 350px;
        padding: 16px;
    }

    .shuffle-letter-card {
        width: min(190px, 72vw);
    }

    .find-target {
        gap: 16px;
    }

    .find-target__card {
        width: 82px;
    }

    .choice-grid,
    .choice-grid--4,
    .choice-grid--6 {
        gap: 10px;
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    .session-result {
        margin-top: 24px;
        padding: 34px 20px;
    }

    .session-result__stats {
        gap: 8px;
    }

    .match-board,
    .hunt-grid {
        gap: 8px;
        padding: 12px;
    }

    .match-board--3 {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    .match-board--6,
    .match-board--10 {
        grid-template-columns: repeat(4, minmax(0, 1fr));
    }

    .match-card {
        border-width: 3px;
        border-radius: 13px;
    }

    .hunt-target {
        grid-template-columns: 1fr auto;
        gap: 12px;
        padding: 14px;
    }

    .hunt-target__remaining {
        grid-column: 1 / -1;
        justify-self: stretch;
    }

    .hunt-target__card {
        width: 72px;
    }

    .hunt-grid--6,
    .hunt-grid--12 {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    .hunt-grid--20 {
        grid-template-columns: repeat(4, minmax(0, 1fr));
    }

    .memory-stage {
        min-height: 330px;
        padding: 18px;
    }

    .memory-preview {
        width: min(165px, 58vw);
    }

    .sequence-prompt { justify-content: flex-start; gap: 8px; padding: 14px; }
    .sequence-slot { width: 74px; }
    .compare-pair { gap: 12px; padding: 16px; grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .quick-arena { grid-template-columns: 90px minmax(140px, 180px); gap: 12px; padding: 18px 12px 30px; }
    .quick-target img { width: 62px; }.quick-current img { width: 125px; }
    .sorting-bins { gap: 10px; }.sorting-bin { min-height: 82px; padding: 10px; }
    .bingo-board { gap: 6px; padding: 10px; grid-template-columns: repeat(var(--bingo-size), minmax(0, 1fr)); }
    .bingo-cell { border-width: 2px; border-radius: 9px; }
}

@media (max-width: 390px) {
    .brand__copy {
        display: none;
    }

    .hero__art {
        min-height: 190px;
    }
}