:root {
    --canvas: #e8f0ed;
    --grid-line: #cadbd5;
    --paper: #fffdf7;
    --paper-muted: #f4f8f6;
    --ink: #16324f;
    --ink-soft: #5f706e;
    --accent: #0f6f64;
    --accent-dark: #0a4d46;
    --accent-soft: #d5ebe5;
    --seal: #e14d3d;
    --gold: #f2c14e;
    --line: #cbd8d4;
    --heart-diamond: #c83f36;
    --spade-club: #15221f;
    --success: #087a62;
    --error: #c43d32;
    --shadow: 0 20px 60px rgba(24, 50, 47, 0.14);
}

.theme-blue {
    --canvas: #e8eff7;
    --grid-line: #c9d6e6;
    --paper-muted: #f1f6fb;
    --accent: #285ea8;
    --accent-dark: #1f477d;
    --accent-soft: #dce8f6;
    --line: #c9d6e4;
}

.theme-green {
    --canvas: #e7f1e8;
    --grid-line: #c8ddca;
    --paper-muted: #f2f8f2;
    --accent: #3e7650;
    --accent-dark: #2c593b;
    --accent-soft: #dcecdf;
    --line: #c9dbc9;
}

.theme-purple {
    --canvas: #eeeaf4;
    --grid-line: #d6cde2;
    --paper-muted: #f8f5fa;
    --accent: #75518f;
    --accent-dark: #563a6b;
    --accent-soft: #eadff1;
    --line: #d7cce0;
}

.theme-pink {
    --canvas: #f5eaec;
    --grid-line: #e3ccd1;
    --paper-muted: #fbf5f6;
    --accent: #a64f61;
    --accent-dark: #7f3948;
    --accent-soft: #f2dde2;
    --line: #e2cdd1;
}

* {
    box-sizing: border-box;
}

html {
    min-width: 320px;
    color-scheme: light;
    scroll-behavior: smooth;
}

body {
    margin: 0;
    min-height: 100vh;
    color: var(--ink);
    background-color: var(--canvas);
    background-image:
        linear-gradient(var(--grid-line) 1px, transparent 1px),
        linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
    background-size: 28px 28px;
    font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    line-height: 1.5;
    overflow-x: hidden;
    -webkit-tap-highlight-color: rgba(15, 111, 100, 0.15);
}

button,
select,
input {
    font: inherit;
}

button,
select,
label {
    touch-action: manipulation;
}

button:focus-visible,
select:focus-visible,
input:focus-visible + .switch-track,
.skip-link:focus-visible {
    outline: 3px solid var(--gold);
    outline-offset: 3px;
}

button:disabled {
    cursor: not-allowed;
}

kbd {
    min-width: 1.55em;
    padding: 0.08em 0.35em;
    border: 1px solid color-mix(in srgb, currentColor 25%, transparent);
    border-bottom-width: 2px;
    border-radius: 5px;
    font-family: "DIN Alternate", "Arial Narrow", monospace;
    font-size: 0.76em;
    font-weight: 700;
    line-height: 1.3;
    text-align: center;
}

.skip-link {
    position: fixed;
    top: 12px;
    left: 12px;
    z-index: 100;
    padding: 10px 14px;
    color: white;
    background: var(--ink);
    border-radius: 8px;
    transform: translateY(-160%);
    transition: transform 160ms ease;
}

.skip-link:focus {
    transform: translateY(0);
}

.app-shell {
    width: min(1180px, calc(100% - 40px));
    margin: 0 auto;
    padding: max(24px, env(safe-area-inset-top)) 0 max(40px, env(safe-area-inset-bottom));
}

.topbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    margin-bottom: 20px;
}

.brand {
    display: flex;
    align-items: center;
    gap: 14px;
    min-width: 0;
}

.brand-mark {
    display: grid;
    flex: 0 0 auto;
    width: 56px;
    height: 56px;
    place-items: center;
    color: var(--paper);
    background: var(--ink);
    border-radius: 15px 15px 15px 4px;
    box-shadow: 5px 5px 0 var(--gold);
    font-family: "DIN Alternate", "Arial Narrow", sans-serif;
    font-size: 1.55rem;
    font-weight: 900;
    font-variant-numeric: tabular-nums;
    letter-spacing: -0.06em;
}

.brand-kicker,
.round-label,
.section-label {
    margin: 0;
    color: var(--accent-dark);
    font-size: 0.74rem;
    font-weight: 800;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.brand h1 {
    margin: -2px 0 0;
    font-family: "STKaiti", "KaiTi", "Kaiti SC", serif;
    font-size: clamp(1.65rem, 3vw, 2.2rem);
    font-weight: 700;
    line-height: 1.1;
    letter-spacing: 0.04em;
}

.topbar-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.button {
    display: inline-flex;
    min-height: 48px;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 11px 18px;
    border: 0;
    border-radius: 12px;
    cursor: pointer;
    font-weight: 800;
    transition: transform 150ms ease, box-shadow 150ms ease, background-color 150ms ease;
}

.button:not(:disabled):hover {
    transform: translateY(-2px);
}

.button:not(:disabled):active {
    transform: translateY(0);
}

.button-quiet {
    color: var(--ink);
    background: var(--paper);
    border: 1px solid var(--line);
    box-shadow: 0 5px 0 color-mix(in srgb, var(--ink) 13%, transparent);
}

.button-secondary {
    color: var(--accent-dark);
    background: var(--accent-soft);
    border: 1px solid color-mix(in srgb, var(--accent) 25%, transparent);
}

.button-primary {
    color: white;
    background: var(--accent);
    box-shadow: 0 6px 0 var(--accent-dark);
}

.button-primary:not(:disabled):hover {
    background: var(--accent-dark);
    box-shadow: 0 8px 0 color-mix(in srgb, var(--accent-dark) 80%, black);
}

.button:disabled {
    opacity: 0.42;
    box-shadow: none;
}

.game-layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 300px;
    gap: 20px;
    align-items: start;
}

.game-stage,
.score-card,
.settings-card,
.rules-card {
    background: var(--paper);
    border: 1px solid color-mix(in srgb, var(--line) 82%, var(--ink));
    box-shadow: var(--shadow);
}

.game-stage {
    position: relative;
    min-width: 0;
    padding: clamp(20px, 4vw, 38px);
    border-radius: 24px 24px 24px 8px;
    overflow: hidden;
}

.game-stage::before {
    position: absolute;
    top: 0;
    left: clamp(28px, 5vw, 54px);
    width: 2px;
    height: 18px;
    background: var(--seal);
    content: "";
    opacity: 0.55;
}

.stage-heading {
    display: flex;
    align-items: end;
    justify-content: space-between;
    gap: 18px;
}

.stage-heading h2 {
    max-width: 620px;
    margin: 4px 0 0;
    font-family: "STKaiti", "KaiTi", "Kaiti SC", serif;
    font-size: clamp(1.75rem, 4vw, 2.65rem);
    line-height: 1.15;
    text-wrap: balance;
}

.progress-pill {
    flex: 0 0 auto;
    padding: 7px 11px;
    color: var(--accent-dark);
    background: var(--accent-soft);
    border-radius: 999px;
    font-family: "DIN Alternate", "Arial Narrow", sans-serif;
    font-size: 0.78rem;
    font-weight: 800;
    font-variant-numeric: tabular-nums;
}

.cards-container {
    display: grid;
    grid-template-columns: repeat(4, minmax(80px, 116px));
    justify-content: center;
    gap: clamp(10px, 2.2vw, 22px);
    min-height: 180px;
    margin-top: clamp(24px, 4vw, 36px);
    align-items: center;
}

.card {
    position: relative;
    width: 100%;
    aspect-ratio: 5 / 7;
    padding: 0;
    color: var(--spade-club);
    background: #fffefb;
    border: 1px solid #d7d2c7;
    border-radius: 15px;
    box-shadow:
        0 13px 25px rgba(31, 46, 41, 0.16),
        inset 0 0 0 5px #fffefb,
        inset 0 0 0 6px #e7e0d5;
    cursor: pointer;
    transform-origin: center bottom;
    transition: transform 170ms ease, box-shadow 170ms ease, opacity 170ms ease, filter 170ms ease;
    user-select: none;
    touch-action: none;
}

.card:nth-child(1) { transform: rotate(-2deg); }
.card:nth-child(2) { transform: rotate(0.7deg); }
.card:nth-child(3) { transform: rotate(-0.6deg); }
.card:nth-child(4) { transform: rotate(1.8deg); }

.card:not(:disabled):hover {
    z-index: 2;
    transform: translateY(-10px) rotate(0deg);
    box-shadow:
        0 20px 34px rgba(31, 46, 41, 0.22),
        inset 0 0 0 5px #fffefb,
        inset 0 0 0 6px var(--accent);
}

.card:not(:disabled):active {
    transform: translateY(-4px) scale(0.98);
}

.card.used {
    opacity: 0.18;
    filter: grayscale(1);
    transform: translateY(12px) scale(0.94);
}

.card.sequence-blocked:not(.used) {
    opacity: 0.48;
    filter: saturate(0.65);
}

.card-corner {
    position: absolute;
    display: flex;
    flex-direction: column;
    align-items: center;
    font-family: Georgia, "Times New Roman", serif;
    font-weight: 700;
    line-height: 0.92;
}

.card-corner-top {
    top: 12px;
    left: 13px;
}

.card-corner-bottom {
    right: 13px;
    bottom: 12px;
    transform: rotate(180deg);
}

.card-value {
    font-size: clamp(1.15rem, 2.2vw, 1.55rem);
}

.card-suit {
    margin-top: 4px;
    font-size: clamp(0.82rem, 1.5vw, 1rem);
}

.card-center {
    position: absolute;
    top: 50%;
    left: 50%;
    font-size: clamp(2rem, 5vw, 3.3rem);
    transform: translate(-50%, -50%);
}

.card-key {
    position: absolute;
    top: 8px;
    right: 8px;
    display: grid;
    width: 22px;
    height: 22px;
    place-items: center;
    color: var(--ink-soft);
    background: #f1eee7;
    border: 1px solid #d8d2c7;
    border-radius: 6px;
    font-family: "DIN Alternate", "Arial Narrow", sans-serif;
    font-size: 0.72rem;
    font-weight: 800;
}

.card.red .card-value,
.card.red .card-suit,
.card.red .card-center {
    color: var(--heart-diamond);
}

.card.black .card-value,
.card.black .card-suit,
.card.black .card-center {
    color: var(--spade-club);
}

.interaction-hint {
    margin: 14px 0 0;
    color: var(--ink-soft);
    font-size: 0.78rem;
    text-align: center;
}

.expression-area {
    margin-top: 28px;
    padding: 20px;
    background: var(--paper-muted);
    border: 1px solid var(--line);
    border-radius: 16px 16px 16px 5px;
    transition: border-color 150ms ease, box-shadow 150ms ease;
}

.expression-area.shake {
    animation: shake 320ms ease;
}

.expression-area.has-invalid-order {
    border-color: color-mix(in srgb, var(--seal) 62%, var(--line));
    box-shadow: inset 3px 0 0 color-mix(in srgb, var(--seal) 76%, transparent);
}

.expression-area.has-invalid-order .expression-hint {
    color: var(--seal);
}

.expression-area.is-drop-target {
    border-color: var(--accent);
    box-shadow: 0 0 0 4px color-mix(in srgb, var(--accent) 16%, transparent);
}

.expression-header {
    display: flex;
    align-items: start;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 14px;
}

.expression-hint {
    margin: 3px 0 0;
    color: var(--ink-soft);
    font-size: 0.82rem;
}

.expression-actions {
    display: flex;
    gap: 4px;
}

.text-button {
    min-height: 36px;
    padding: 6px 9px;
    color: var(--accent-dark);
    background: transparent;
    border: 0;
    border-radius: 7px;
    cursor: pointer;
    font-size: 0.8rem;
    font-weight: 700;
}

.text-button:not(:disabled):hover {
    background: var(--accent-soft);
}

.text-button:disabled {
    opacity: 0.36;
}

.equation-line {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 76px;
    gap: 12px;
    align-items: center;
}

.expression-display {
    position: relative;
    display: flex;
    min-width: 0;
    min-height: 78px;
    align-items: center;
    gap: 7px;
    padding: 10px 5px 6px;
    border-bottom: 2px solid var(--ink);
    overflow-x: auto;
    scrollbar-width: thin;
}

.expression-display.is-drag-over {
    background: color-mix(in srgb, var(--accent-soft) 72%, transparent);
}

.expression-display.drop-at-end::after {
    flex: 0 0 3px;
    width: 3px;
    height: 58px;
    margin-left: 1px;
    background: var(--seal);
    border-radius: 999px;
    content: "";
}

.expression-placeholder {
    color: color-mix(in srgb, var(--ink-soft) 65%, transparent);
    font-family: "STKaiti", "KaiTi", "Kaiti SC", serif;
    font-size: 1.15rem;
}

.expression-item {
    position: relative;
    display: inline-flex;
    flex: 0 0 auto;
    min-width: 46px;
    min-height: 48px;
    align-items: center;
    justify-content: center;
    padding: 6px 10px;
    color: var(--ink);
    background: var(--paper);
    border: 1px solid var(--line);
    border-radius: 9px;
    box-shadow: 0 3px 0 color-mix(in srgb, var(--ink) 13%, transparent);
    cursor: grab;
    font-family: "DIN Alternate", "Arial Narrow", "PingFang SC", sans-serif;
    font-size: 1.28rem;
    font-weight: 800;
    transition: transform 140ms ease, background-color 140ms ease, color 140ms ease;
    touch-action: none;
    user-select: none;
}

.expression-item:hover {
    color: white;
    background: var(--seal);
    transform: translateY(-2px);
}

.expression-item:active {
    cursor: grabbing;
}

.expression-item.is-dragging {
    opacity: 0.28;
    transform: scale(0.94);
}

.expression-item.drop-before::before,
.expression-item.drop-after::after {
    position: absolute;
    top: -5px;
    bottom: -5px;
    width: 3px;
    background: var(--seal);
    border-radius: 999px;
    content: "";
}

.expression-item.drop-before::before {
    left: -6px;
}

.expression-item.drop-after::after {
    right: -6px;
}

.expression-dragging,
.expression-dragging * {
    cursor: grabbing !important;
    user-select: none !important;
}

.drag-ghost {
    position: fixed !important;
    z-index: 1000 !important;
    margin: 0 !important;
    pointer-events: none !important;
    opacity: 0.94 !important;
    filter: none !important;
    transform: translate(-50%, -50%) rotate(2deg) scale(1.06) !important;
    box-shadow: 0 22px 42px rgba(31, 46, 41, 0.28) !important;
    transition: none !important;
}

.is-drag-source {
    opacity: 0.32 !important;
}

.expression-operator {
    color: var(--accent-dark);
    background: var(--accent-soft);
    border-color: color-mix(in srgb, var(--accent) 30%, var(--line));
}

.expression-bracket {
    min-width: 34px;
    padding-inline: 7px;
    color: var(--seal);
    background: transparent;
    border-color: transparent;
    box-shadow: none;
    font-size: 1.6rem;
}

.target-seal {
    display: grid;
    width: 72px;
    height: 72px;
    place-content: center;
    color: var(--seal);
    border: 3px double currentColor;
    border-radius: 50%;
    opacity: 0.42;
    transform: rotate(-7deg);
    transition: transform 180ms ease, opacity 180ms ease, color 180ms ease, background-color 180ms ease;
}

.target-seal span {
    margin-bottom: -4px;
    font-family: "STKaiti", "KaiTi", serif;
    font-size: 0.66rem;
    text-align: center;
}

.target-seal strong {
    font-family: "DIN Alternate", "Arial Narrow", sans-serif;
    font-size: 1.95rem;
    font-variant-numeric: tabular-nums;
    line-height: 1;
}

.target-seal.ready {
    opacity: 1;
    transform: rotate(-7deg) scale(1.06);
}

.target-seal.solved {
    color: white;
    background: var(--seal);
    opacity: 1;
    transform: rotate(-7deg) scale(1.08);
}

.keypad {
    display: flex;
    gap: 12px;
    margin-top: 14px;
}

.keypad-group {
    display: grid;
    flex: 1;
    grid-template-columns: repeat(4, minmax(56px, 1fr));
    gap: 8px;
}

.keypad-brackets {
    flex: 0 0 150px;
    grid-template-columns: repeat(2, 1fr);
    padding-left: 12px;
    border-left: 1px dashed var(--line);
}

.tool-button {
    display: grid;
    min-height: 58px;
    place-items: center;
    padding: 6px;
    color: var(--ink);
    background: var(--paper);
    border: 1px solid var(--line);
    border-radius: 11px;
    box-shadow: 0 4px 0 color-mix(in srgb, var(--ink) 13%, transparent);
    cursor: pointer;
    transition: transform 140ms ease, background-color 140ms ease, box-shadow 140ms ease, opacity 140ms ease;
    touch-action: none;
    user-select: none;
}

.tool-button span {
    font-family: "DIN Alternate", "Arial Narrow", sans-serif;
    font-size: 1.5rem;
    font-weight: 800;
    line-height: 1;
}

.tool-button kbd {
    color: var(--ink-soft);
    font-size: 0.58rem;
}

.tool-button:not(.sequence-blocked):hover {
    color: white;
    background: var(--accent);
    box-shadow: 0 6px 0 var(--accent-dark);
    transform: translateY(-2px);
}

.tool-button:not(.sequence-blocked):hover kbd {
    color: white;
}

.tool-button.sequence-blocked {
    opacity: 0.28;
    box-shadow: 0 2px 0 color-mix(in srgb, var(--ink) 9%, transparent);
}

.tool-bracket {
    color: var(--seal);
}

.primary-actions {
    display: grid;
    grid-template-columns: minmax(120px, 0.45fr) minmax(180px, 1fr);
    gap: 10px;
    margin-top: 16px;
}

.result-area {
    position: relative;
    margin-top: 16px;
    overflow: hidden;
}

.result-area[hidden] {
    display: none;
}

.result-message {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 0 14px;
    padding: 15px 17px;
    border: 1px solid;
    border-radius: 12px;
    animation: result-in 180ms ease-out;
}

.result-message strong {
    grid-row: 1 / 3;
    align-self: center;
    font-family: "STKaiti", "KaiTi", serif;
    font-size: 1.2rem;
}

.result-message span {
    min-width: 0;
    font-family: "DIN Alternate", "Arial Narrow", "PingFang SC", sans-serif;
    font-weight: 800;
    overflow-wrap: anywhere;
}

.result-message small {
    color: var(--ink-soft);
}

.result-success {
    color: var(--success);
    background: #e7f5ef;
    border-color: #a9d9c8;
}

.result-error {
    color: var(--error);
    background: #fff0ed;
    border-color: #efc0b9;
}

.result-solution {
    color: var(--accent-dark);
    background: var(--accent-soft);
    border-color: color-mix(in srgb, var(--accent) 35%, var(--line));
}

.side-panel {
    display: grid;
    gap: 14px;
}

.score-card,
.settings-card,
.rules-card {
    padding: 20px;
    border-radius: 17px 17px 17px 6px;
    box-shadow: 0 12px 34px rgba(24, 50, 47, 0.1);
}

.score-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
    margin: 16px 0 0;
}

.score-grid div {
    min-width: 0;
    padding: 10px 5px;
    background: var(--paper-muted);
    border: 1px solid var(--line);
    border-radius: 9px;
    text-align: center;
}

.score-grid dt {
    color: var(--ink-soft);
    font-size: 0.66rem;
}

.score-grid dd {
    margin: 2px 0 0;
    font-family: "DIN Alternate", "Arial Narrow", sans-serif;
    font-size: 1.55rem;
    font-weight: 900;
    font-variant-numeric: tabular-nums;
}

.settings-card .section-label,
.rules-card .section-label {
    margin-bottom: 14px;
}

.field-row,
.switch-row {
    display: flex;
    min-height: 48px;
    align-items: center;
    justify-content: space-between;
    gap: 14px;
    color: var(--ink);
    font-size: 0.82rem;
}

.field-row {
    padding-bottom: 12px;
    border-bottom: 1px solid var(--line);
}

.field-row select {
    max-width: 130px;
    padding: 7px 28px 7px 9px;
    color: var(--ink);
    background-color: var(--paper-muted);
    border: 1px solid var(--line);
    border-radius: 8px;
}

.target-field > span {
    display: grid;
}

.target-field strong {
    font-size: 0.82rem;
}

.target-field small {
    color: var(--ink-soft);
    font-size: 0.68rem;
}

.target-field input {
    width: 78px;
    padding: 7px 8px;
    color: var(--ink);
    background: var(--paper-muted);
    border: 1px solid var(--line);
    border-radius: 8px;
    font: 800 0.9rem/1 "DIN Alternate", "Arial Narrow", sans-serif;
    text-align: center;
}

.settings-status {
    margin: 12px 0 0;
    padding: 9px 10px;
    color: var(--accent-dark);
    background: var(--accent-soft);
    border-radius: 8px;
    font-size: 0.72rem;
    font-weight: 700;
}

.settings-status[hidden] {
    display: none;
}

.settings-status.is-error {
    color: var(--seal);
    background: color-mix(in srgb, var(--seal) 10%, var(--paper));
}

.switch-row {
    position: relative;
    padding-top: 12px;
    cursor: pointer;
}

.switch-row > span:first-child {
    display: grid;
}

.switch-row strong {
    font-size: 0.82rem;
}

.switch-row small {
    color: var(--ink-soft);
    font-size: 0.68rem;
}

.switch-row input {
    position: absolute;
    width: 1px;
    height: 1px;
    opacity: 0;
}

.switch-track {
    position: relative;
    flex: 0 0 auto;
    width: 42px;
    height: 24px;
    background: #c4cecb;
    border-radius: 999px;
    transition: background-color 150ms ease;
}

.switch-track::after {
    position: absolute;
    top: 3px;
    left: 3px;
    width: 18px;
    height: 18px;
    background: white;
    border-radius: 50%;
    box-shadow: 0 2px 5px rgba(22, 50, 79, 0.2);
    content: "";
    transition: transform 150ms ease;
}

.switch-row input:checked + .switch-track {
    background: var(--accent);
}

.switch-row input:checked + .switch-track::after {
    transform: translateX(18px);
}

.rules-card p:not(.section-label) {
    margin: 0;
    color: var(--ink-soft);
    font-size: 0.82rem;
    line-height: 1.7;
}

.rules-card .rules-tip {
    margin-top: 10px;
    padding-top: 10px;
    color: var(--accent-dark);
    border-top: 1px dashed var(--line);
}

.confetti {
    position: absolute;
    top: 50%;
    left: 50%;
    z-index: 5;
    width: 8px;
    height: 14px;
    background: var(--confetti-color);
    pointer-events: none;
    animation: confetti-burst 900ms cubic-bezier(0.18, 0.78, 0.28, 1) var(--confetti-delay) forwards;
}

.card-enter {
    animation: card-enter 430ms cubic-bezier(0.22, 0.8, 0.28, 1) var(--enter-delay) both;
}

.card-exit {
    animation: card-exit 210ms ease-in var(--exit-delay) both;
}

@keyframes card-enter {
    from { opacity: 0; transform: translateY(-24px) rotate(-5deg); }
}

@keyframes card-exit {
    to { opacity: 0; transform: translateY(-20px) rotate(4deg) scale(0.94); }
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-6px); }
    75% { transform: translateX(6px); }
}

@keyframes result-in {
    from { opacity: 0; transform: translateY(6px); }
}

@keyframes confetti-burst {
    to {
        opacity: 0;
        transform: translate(var(--confetti-x), -100px) rotate(var(--confetti-r));
    }
}

@media (max-width: 920px) {
    .game-layout {
        grid-template-columns: minmax(0, 1fr);
    }

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

    .rules-card {
        grid-column: 1 / -1;
    }
}

@media (max-width: 640px) {
    body {
        background-size: 22px 22px;
    }

    .app-shell {
        width: min(100% - 20px, 560px);
        padding-top: max(14px, env(safe-area-inset-top));
    }

    .topbar {
        gap: 12px;
        margin-bottom: 12px;
    }

    .brand {
        gap: 10px;
    }

    .brand-mark {
        width: 46px;
        height: 46px;
        border-radius: 12px 12px 12px 3px;
        font-size: 1.25rem;
    }

    .brand-kicker,
    .button-quiet kbd {
        display: none;
    }

    .brand h1 {
        font-size: 1.5rem;
    }

    .button-quiet {
        min-height: 44px;
        padding: 9px 12px;
    }

    .game-stage {
        padding: 18px 14px 20px;
        border-radius: 18px 18px 18px 6px;
    }

    .stage-heading {
        align-items: start;
    }

    .stage-heading h2 {
        font-size: clamp(1.55rem, 7vw, 2rem);
    }

    .progress-pill {
        margin-top: 2px;
        white-space: nowrap;
    }

    .cards-container {
        grid-template-columns: repeat(4, minmax(0, 1fr));
        gap: 7px;
        min-height: 0;
        margin-top: 22px;
    }

    .card {
        border-radius: 10px;
        box-shadow:
            0 7px 14px rgba(31, 46, 41, 0.14),
            inset 0 0 0 3px #fffefb,
            inset 0 0 0 4px #e7e0d5;
    }

    .card-corner-top {
        top: 8px;
        left: 8px;
    }

    .card-corner-bottom {
        right: 8px;
        bottom: 8px;
    }

    .card-key {
        top: 5px;
        right: 5px;
        width: 18px;
        height: 18px;
        font-size: 0.62rem;
    }

    .interaction-hint {
        margin-top: 10px;
    }

    .expression-area {
        margin-top: 18px;
        padding: 14px;
    }

    .expression-header {
        gap: 8px;
    }

    .text-button kbd {
        display: none;
    }

    .equation-line {
        grid-template-columns: minmax(0, 1fr) 62px;
        gap: 8px;
    }

    .expression-display {
        min-height: 64px;
        gap: 5px;
    }

    .expression-item {
        min-width: 40px;
        min-height: 42px;
        padding: 5px 8px;
        font-size: 1.08rem;
    }

    .target-seal {
        width: 60px;
        height: 60px;
    }

    .target-seal strong {
        font-size: 1.65rem;
    }

    .keypad {
        display: grid;
        gap: 8px;
    }

    .keypad-group,
    .keypad-brackets {
        width: 100%;
    }

    .keypad-brackets {
        grid-template-columns: repeat(2, 1fr);
        padding: 8px 0 0;
        border-top: 1px dashed var(--line);
        border-left: 0;
    }

    .tool-button {
        min-height: 52px;
    }

    .primary-actions {
        position: sticky;
        bottom: max(8px, env(safe-area-inset-bottom));
        z-index: 10;
        grid-template-columns: 0.42fr 1fr;
        padding: 8px;
        margin: 10px -8px -8px;
        background: color-mix(in srgb, var(--paper) 88%, transparent);
        border: 1px solid color-mix(in srgb, var(--line) 72%, transparent);
        border-radius: 14px;
        backdrop-filter: blur(10px);
    }

    .primary-actions .button {
        min-height: 46px;
        padding-inline: 10px;
    }

    .primary-actions kbd {
        display: none;
    }

    .result-message {
        grid-template-columns: 1fr;
        gap: 3px;
    }

    .result-message strong {
        grid-row: auto;
    }

    .side-panel {
        grid-template-columns: 1fr;
    }

    .rules-card {
        grid-column: auto;
    }
}

@media (max-width: 390px) {
    .app-shell {
        width: min(100% - 12px, 380px);
    }

    .topbar-actions {
        gap: 6px;
    }

    .stage-heading {
        display: block;
    }

    .progress-pill {
        display: inline-block;
        margin-top: 8px;
    }

    .interaction-hint kbd {
        display: none;
    }

    .expression-actions {
        gap: 0;
    }

    .text-button {
        padding-inline: 6px;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}