.chain-title {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-3);
}

.chain-title h1 {
    margin: 0;
}

.chain-help span {
    display: inline-grid;
    place-items: center;
    width: 1.3rem;
    height: 1.3rem;
    border-radius: 999px;
    background: var(--brand);
    color: var(--brand-contrast);
    font-size: 0.8rem;
}

/* --- Mode switch --- */

.chain-tabs {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4px;
    max-width: 28rem;
    margin-bottom: var(--space-4);
    padding: 4px;
    border: 1px solid var(--border);
    border-radius: 999px;
    background: var(--surface-2);
}

.chain-tab {
    min-height: 2.5rem;
    padding: 0 var(--space-2);
    border: 0;
    border-radius: 999px;
    background: transparent;
    color: var(--text-2);
    font: inherit;
    font-weight: 700;
    font-size: 0.9rem;
    white-space: nowrap;
    cursor: pointer;
}

.chain-tab.is-active {
    background: var(--surface);
    color: var(--text);
    box-shadow: var(--shadow);
}

/* --- Intro card --- */

.chain-intro {
    display: grid;
    gap: var(--space-4);
    margin-bottom: var(--space-4);
}

.chain-intro > * {
    min-width: 0;
}

.chain-preview {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
    align-items: center;
    gap: var(--space-2);
    max-width: 24rem;
}

.chain-preview .chain-mini span {
    width: auto;
    height: auto;
    min-width: 0;
    aspect-ratio: 1;
}

.chain-mini {
    display: grid;
    grid-template-columns: repeat(var(--len, 5), minmax(0, 1fr));
    gap: 4px;
}

.chain-mini span {
    display: grid;
    place-items: center;
    width: clamp(1.4rem, 7vw, 2rem);
    height: clamp(1.4rem, 7vw, 2rem);
    border: 2px solid var(--border-strong);
    border-radius: 6px;
    background: var(--surface);
    color: var(--muted);
    font-weight: 800;
    text-transform: uppercase;
}

.chain-mini--start span {
    color: var(--text);
}

.chain-mini--goal span {
    border-color: var(--tile-correct);
    background: color-mix(in srgb, var(--tile-correct) 14%, var(--surface));
}

.chain-mini--small {
    gap: 3px;
}

.chain-mini--small span {
    width: clamp(1.2rem, 5.2vw, 1.6rem);
    height: clamp(1.2rem, 5.2vw, 1.6rem);
    border-width: 1.5px;
    font-size: 0.8rem;
    color: var(--text);
}

.chain-arrow {
    color: var(--muted);
    font-size: 1.3rem;
    font-weight: 800;
}

.chain-facts {
    display: grid;
    gap: var(--space-2);
    margin: 0;
    padding: 0;
    list-style: none;
}

.chain-facts li {
    position: relative;
    padding-left: 1.6rem;
    color: var(--text-2);
}

.chain-facts li::before {
    content: "";
    position: absolute;
    top: 0.45em;
    left: 0.25rem;
    width: 0.6rem;
    height: 0.6rem;
    border-radius: 3px;
    background: var(--tile-correct);
}

.chain-record {
    margin: 0;
    color: var(--muted);
    font-weight: 600;
}

.chain-intro-actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2);
}

.chain-intro-actions > * {
    flex: 1 1 9rem;
}

/* --- Play area --- */

.chain-hud {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-3);
    margin-bottom: var(--space-2);
}

.chain-goal-block {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 4px;
}

.chain-goal {
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.chain-hint {
    margin: 0;
    color: var(--muted);
    font-size: 0.85rem;
    text-align: right;
}

.chain-hint.is-ready {
    display: flex;
    align-items: center;
    gap: 8px;
}

.chain-hint-letters {
    display: inline-flex;
    gap: 4px;
}

.chain-hint-letters span {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.75rem;
    height: 1.75rem;
    border-radius: 6px;
    background: var(--tile-present);
    color: var(--tile-text);
    font-size: 1rem;
    font-weight: 800;
}

.chain-timer,
.chain-steps {
    padding: 0.3rem 0.8rem;
    border-radius: 999px;
    background: var(--surface-2);
    font-variant-numeric: tabular-nums;
    font-weight: 800;
}

.chain-timer {
    font-size: 1.15rem;
}

.chain-sub {
    margin: 0 0 var(--space-3);
    color: var(--muted);
}

.chain-board {
    display: grid;
    gap: 6px;
    max-width: 22rem;
    margin: 0 0 6px;
    padding: 0;
    list-style: none;
}

.chain-row {
    display: grid;
    grid-template-columns: 1.6rem repeat(var(--len, 5), minmax(0, 1fr));
    align-items: center;
    gap: 6px;
}

.chain-row-num {
    color: var(--muted);
    font-size: 0.8rem;
    font-weight: 700;
    text-align: right;
}

.chain-row--target .game-tile {
    border-style: dashed;
    border-color: var(--tile-correct);
    background: color-mix(in srgb, var(--tile-correct) 10%, var(--surface));
    color: var(--muted);
}

.chain-row--gap {
    color: var(--muted);
    font-size: 0.85rem;
    text-align: center;
    padding-left: 1.6rem;
}

.chain-tile--changed {
    border-color: var(--tile-present);
    background: var(--tile-present);
    color: var(--tile-text);
}

.chain-entry {
    display: grid;
    grid-template-columns: 1.6rem repeat(var(--len, 5), minmax(0, 1fr));
    gap: 6px;
    max-width: 22rem;
    margin-bottom: var(--space-2);
}

.chain-finish {
    margin: calc(-1 * var(--space-1)) 0 var(--space-3);
}

.chain-finish:empty {
    display: none;
}

.chain-entry .game-tile--filled {
    border-color: var(--brand);
}

.chain-entry.is-shake,
.chain-board.is-shake {
    animation: game-shake 0.35s;
}

.chain-status {
    min-height: 1.5em;
    margin: 0 0 var(--space-2);
    color: var(--text-2);
    font-weight: 600;
}

.keyboard {
    display: grid;
    gap: 6px;
    max-width: 34rem;
    margin: 0 0 var(--space-3);
    user-select: none;
    -webkit-user-select: none;
}

.keyboard-row {
    display: flex;
    justify-content: center;
    gap: 5px;
}

.key {
    flex: 1 1 0;
    max-width: 2.75rem;
    min-width: 0;
    height: 3.1rem;
    padding: 0;
    border: 0;
    border-radius: 6px;
    background: var(--surface-3);
    color: var(--text);
    font: inherit;
    font-size: clamp(0.85rem, 3.6vw, 1.05rem);
    font-weight: 700;
    text-transform: uppercase;
    touch-action: manipulation;
    cursor: pointer;
}

.key:hover {
    filter: brightness(0.96);
}

.key:active {
    transform: scale(0.95);
}

.key--wide {
    flex: 1.5 1 0;
    max-width: 4.4rem;
    font-size: 0.95rem;
    text-transform: none;
}

.chain-actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2);
    margin: var(--space-4) 0;
}

.chain-name {
    display: grid;
    gap: var(--space-3);
    max-width: 24rem;
    margin-bottom: var(--space-4);
}

.chain-leaders {
    margin: 0;
    padding: 0;
    list-style: none;
    counter-reset: place;
}

.chain-leaders li {
    display: flex;
    justify-content: space-between;
    gap: var(--space-3);
    padding: 0.45rem 0;
    border-bottom: 1px solid var(--border);
    counter-increment: place;
}

.chain-leaders li:last-child {
    border-bottom: 0;
}

.chain-leaders li::before {
    content: counter(place);
    min-width: 1.5rem;
    color: var(--muted);
    font-weight: 700;
}

.chain-leaders li.is-empty::before {
    content: none;
}

.chain-leaders .chain-leader-name {
    flex: 1;
}

.chain-leaders .chain-leader-time {
    font-variant-numeric: tabular-nums;
    font-weight: 700;
}

.chain-leaders .is-current {
    font-weight: 800;
    color: var(--brand);
}

.chain-solution {
    margin: var(--space-2) 0 0;
    color: var(--text-2);
    font-weight: 600;
}

/* --- Tutorial --- */

.chain-tutorial {
    width: min(26rem, calc(100vw - 2rem));
    margin: auto;
    padding: var(--space-5);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    background: var(--surface);
    color: var(--text);
    box-shadow: var(--shadow-lg);
}

.chain-tutorial::backdrop {
    background: rgb(0 0 0 / 0.45);
}

.chain-tutorial-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-3);
    margin-bottom: var(--space-3);
}

.chain-tutorial-head h2 {
    margin: 0;
    font-size: 1.2rem;
}

.chain-tutorial-close {
    width: 2rem;
    height: 2rem;
    border: 0;
    border-radius: 999px;
    background: var(--surface-2);
    color: var(--text);
    font: inherit;
    font-size: 1.25rem;
    line-height: 1;
    cursor: pointer;
}

.chain-board--demo {
    --len: 5;
    margin-inline: auto;
    max-width: 18rem;
}

.chain-board--demo .chain-row {
    animation: chain-pop 0.3s ease-out;
}

.chain-tutorial-text {
    min-height: 4.5em;
    margin: var(--space-3) 0;
    color: var(--text-2);
}

.chain-tutorial-dots {
    display: flex;
    justify-content: center;
    gap: 6px;
    margin-bottom: var(--space-3);
}

.chain-tutorial-dots span {
    width: 8px;
    height: 8px;
    border-radius: 999px;
    background: var(--border-strong);
}

.chain-tutorial-dots span.is-active {
    background: var(--brand);
}

.chain-tutorial-actions {
    display: flex;
    justify-content: space-between;
    gap: var(--space-2);
}

@keyframes chain-pop {
    from { opacity: 0; transform: translateY(-4px); }
    to { opacity: 1; transform: none; }
}

@media (prefers-reduced-motion: reduce) {
    .chain-board--demo .chain-row {
        animation: none;
    }
}

.chain-free-card {
    display: grid;
    gap: var(--space-3);
    margin-bottom: var(--space-5);
}

.chain-lengths {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2);
}

.chain-lengths .is-active {
    background: var(--brand);
    border-color: var(--brand);
    color: #fff;
}

.chain-days {
    display: grid;
    gap: var(--space-5);
}

.chain-day-flag {
    display: inline-block;
    margin: 0 0 var(--space-3);
    padding: 0.35rem 0.9rem 0.35rem 0.7rem;
    background: var(--brand);
    color: #fff;
    font-size: 0.95rem;
    clip-path: polygon(0 0, calc(100% - 0.7rem) 0, 100% 50%, calc(100% - 0.7rem) 100%, 0 100%);
}

.chain-day-cards {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: var(--space-3);
}

.chain-card {
    display: grid;
    justify-items: center;
    gap: 0.35rem;
    padding: var(--space-3);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--surface);
    color: inherit;
    text-align: center;
    text-decoration: none;
}

.chain-card:hover {
    border-color: var(--brand);
}

.chain-card-title {
    font-weight: 700;
}

.chain-card-preview {
    display: grid;
    grid-template-columns: none;
    justify-items: center;
    gap: 0.15rem;
    max-width: none;
}

.chain-card-preview .chain-arrow {
    font-size: 0.9rem;
    line-height: 1;
    transform: rotate(90deg);
}

.chain-card-preview .chain-mini span {
    width: 1.75rem;
    height: 1.75rem;
    aspect-ratio: auto;
    font-size: 0.9rem;
    border-width: 1.5px;
    border-radius: 5px;
}

.chain-meta,
.chain-counts {
    display: flex;
    flex-wrap: nowrap;
    justify-content: center;
    align-items: center;
    gap: 0.35rem 0.5rem;
    max-width: 100%;
}

.chain-counts {
    white-space: nowrap;
}

.chain-stars {
    color: #e0a106;
    letter-spacing: 0.12em;
}

.chain-level {
    color: var(--text-2);
    font-weight: 700;
    text-transform: lowercase;
}

.chain-counts,
.chain-record {
    color: var(--muted);
    font-size: 0.85rem;
}

@media (max-width: 720px) {
    .chain-day-cards {
        grid-template-columns: 1fr;
    }
}