.ttt-main {
    width: min(1000px, calc(100% - 2rem));
    margin: 0 auto;
    padding: clamp(1.5rem, 4vw, 3rem) 0 2rem;
}

.ttt-intro {
    margin: 0 auto clamp(1.5rem, 4vw, 2.5rem);
    text-align: center;
}

.ttt-intro h1 {
    margin-bottom: 0.65rem;
    white-space: normal;
}

.ttt-mode-picker,
.ttt-game {
    width: min(100%, 650px);
    margin: 0 auto;
}

.ttt-mode-picker {
    padding: clamp(1.25rem, 4vw, 2rem);
    text-align: center;
    background: var(--surface);
    border: 1px solid var(--card-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.ttt-mode-picker h2 {
    margin-bottom: 0.5rem;
    white-space: normal;
}

.ttt-mode-options {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.8rem;
    margin-top: 1.5rem;
}

.ttt-mode-button {
    display: flex;
    min-height: 7rem;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 0.4rem;
    padding: 1rem;
    color: var(--text);
    font: inherit;
    text-align: center;
    background: var(--bg);
    border: 1px solid var(--card-border);
    border-radius: 0.9rem;
    cursor: pointer;
    transition: transform 0.18s ease, border-color 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
}

.ttt-mode-name {
    font-weight: 700;
    font-size: 1.05rem;
}

.ttt-mode-description {
    font-size: 0.8rem;
    color: var(--muted);
}

@media (hover: hover) {
    .ttt-mode-button:hover {
        transform: translateY(-3px);
        border-color: var(--text);
        box-shadow: var(--shadow);
    }
}

.ttt-mode-button:focus-visible,
.ttt-action:focus-visible,
.ttt-cell:focus-visible,
.ttt-text-button:focus-visible {
    outline: 3px solid var(--text);
    outline-offset: 3px;
}

.ttt-game[hidden],
.ttt-mode-picker[hidden],
.ttt-paused-overlay[hidden],
.ttt-win-line[hidden] {
    display: none !important;
}

.ttt-status {
    min-height: 1.7rem;
    margin-bottom: 0.7rem;
    font-size: clamp(0.95rem, 2.5vw, 1.1rem);
    font-weight: 600;
    text-align: center;
}

.ttt-board-frame {
    padding: clamp(0.6rem, 2vw, 0.9rem);
    background: var(--surface);
    border: 1px solid var(--card-border);
    border-radius: clamp(0.9rem, 2.5vw, 1.25rem);
    box-shadow: var(--shadow);
}

.ttt-actions {
    display: flex;
    justify-content: space-between;
    gap: 0.6rem;
    margin-bottom: clamp(0.55rem, 1.8vw, 0.85rem);
}

.ttt-action {
    min-height: 2.75rem;
    padding: 0.55rem 1rem;
    color: var(--text);
    font: 600 0.8rem "Tomorrow", sans-serif;
    background: var(--bg);
    border: 1px solid var(--card-border);
    border-radius: 0.7rem;
    cursor: pointer;
    transition: transform 0.18s ease, background 0.18s ease, color 0.18s ease;
}

.ttt-action:hover,
.ttt-action.is-active {
    color: var(--bg);
    background: var(--text);
    transform: translateY(-1px);
}

.ttt-board {
    position: relative;
    display: grid;
    width: 100%;
    aspect-ratio: 1;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    grid-template-rows: repeat(3, minmax(0, 1fr));
    gap: clamp(0.45rem, 1.5vw, 0.75rem);
    isolation: isolate;
}

.ttt-cell {
    display: grid;
    min-width: 0;
    min-height: 0;
    place-items: center;
    padding: 0;
    color: var(--text);
    font: 700 clamp(3rem, 15vw, 6.5rem) "Tomorrow", sans-serif;
    line-height: 1;
    background: var(--bg);
    border: 1px solid var(--card-border);
    border-radius: clamp(0.75rem, 2vw, 1rem);
    cursor: pointer;
    transition: background 0.18s ease, border-color 0.18s ease, transform 0.18s ease, box-shadow 0.18s ease;
    -webkit-tap-highlight-color: transparent;
}

.ttt-cell:disabled {
    cursor: default;
}

.ttt-cell:not(:disabled):hover {
    background: var(--surface);
    border-color: var(--text);
}

.ttt-cell.mark-o {
    opacity: 0.72;
}

.ttt-cell.is-winning {
    background: color-mix(in srgb, var(--text) 10%, var(--surface));
    border-color: var(--text);
    box-shadow: 0 0 0 2px color-mix(in srgb, var(--text) 20%, transparent), var(--shadow);
}

.ttt-win-line {
    position: absolute;
    z-index: 2;
    display: block;
    opacity: 0;
    background: var(--text);
    border-radius: 999px;
    box-shadow: 0 0 12px color-mix(in srgb, var(--text) 50%, transparent), 0 0 26px color-mix(in srgb, var(--text) 24%, transparent);
    pointer-events: none;
}

.ttt-win-line.is-visible {
    opacity: 1;
    animation: ttt-line-glow 0.7s ease-out both;
}

.ttt-win-line[data-line^="row-"] {
    left: 10%;
    width: 80%;
    height: 5px;
    transform: translateY(-50%) scaleX(0.2);
}

.ttt-win-line[data-line="row-0"] { top: 16.67%; }
.ttt-win-line[data-line="row-1"] { top: 50%; }
.ttt-win-line[data-line="row-2"] { top: 83.33%; }

.ttt-win-line[data-line^="column-"] {
    top: 10%;
    width: 5px;
    height: 80%;
    transform: translateX(-50%) scaleY(0.2);
}

.ttt-win-line[data-line="column-0"] { left: 16.67%; }
.ttt-win-line[data-line="column-1"] { left: 50%; }
.ttt-win-line[data-line="column-2"] { left: 83.33%; }

.ttt-win-line[data-line="diagonal-down"],
.ttt-win-line[data-line="diagonal-up"] {
    top: 50%;
    left: 3%;
    width: 94%;
    height: 5px;
}

.ttt-win-line[data-line="diagonal-down"] {
    transform: translateY(-50%) rotate(45deg) scaleX(0.2);
}

.ttt-win-line[data-line="diagonal-up"] {
    transform: translateY(-50%) rotate(-45deg) scaleX(0.2);
}

.ttt-win-line.is-visible[data-line^="row-"] {
    animation-name: ttt-line-row;
}

.ttt-win-line.is-visible[data-line^="column-"] {
    animation-name: ttt-line-column;
}

.ttt-win-line.is-visible[data-line="diagonal-down"],
.ttt-win-line.is-visible[data-line="diagonal-up"] {
    animation-name: ttt-line-diagonal;
}

@keyframes ttt-line-row {
    from { opacity: 0; transform: translateY(-50%) scaleX(0.2); }
    to { opacity: 1; transform: translateY(-50%) scaleX(1); }
}

@keyframes ttt-line-column {
    from { opacity: 0; transform: translateX(-50%) scaleY(0.2); }
    to { opacity: 1; transform: translateX(-50%) scaleY(1); }
}

@keyframes ttt-line-diagonal {
    from { opacity: 0; transform: translateY(-50%) rotate(var(--line-angle)) scaleX(0.2); }
    to { opacity: 1; transform: translateY(-50%) rotate(var(--line-angle)) scaleX(1); }
}

.ttt-win-line.is-visible[data-line="diagonal-down"] { --line-angle: 45deg; }
.ttt-win-line.is-visible[data-line="diagonal-up"] { --line-angle: -45deg; }

.ttt-paused-overlay {
    position: absolute;
    z-index: 3;
    inset: 0;
    display: grid;
    place-items: center;
    color: var(--text);
    font-size: clamp(1.5rem, 7vw, 2.5rem);
    font-weight: 700;
    background: color-mix(in srgb, var(--bg) 82%, transparent);
    border-radius: inherit;
    backdrop-filter: blur(3px);
    -webkit-backdrop-filter: blur(3px);
}

.ttt-game-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    margin-top: 0.75rem;
}

.ttt-text-button {
    padding: 0.35rem 0;
    color: var(--muted);
    font: 500 0.8rem "Tomorrow", sans-serif;
    background: transparent;
    border: 0;
    cursor: pointer;
}

.ttt-text-button:hover {
    color: var(--text);
    text-decoration: underline;
}

.ttt-mode-label {
    font-size: 0.75rem;
    color: var(--muted);
}

@keyframes ttt-line-glow {
    0% { filter: brightness(0.8); }
    60% { filter: brightness(1.5); }
    100% { filter: brightness(1); }
}

@media (max-width: 520px) {
    .ttt-main {
        width: calc(100% - 1rem);
        padding-top: 1.25rem;
    }

    .ttt-mode-options {
        grid-template-columns: 1fr;
        gap: 0.6rem;
        margin-top: 1rem;
    }

    .ttt-mode-button {
        min-height: 5.25rem;
    }

    .ttt-board-frame {
        padding: 0.55rem;
    }

    .ttt-cell {
        font-size: clamp(2.75rem, 19vw, 4.5rem);
    }
}

@media (prefers-reduced-motion: reduce) {
    .ttt-mode-button,
    .ttt-action,
    .ttt-cell,
    .ttt-win-line.is-visible {
        transition: none;
        animation: none;
    }
}

/* Keep the complete game in a persistent, near-square play box. */
.ttt-game {
    position: relative;
    display: block;
    width: min(100%, 620px, 78vh);
    width: min(100%, 620px, 78dvh);
    aspect-ratio: 1;
    margin: 0 auto;
    padding: clamp(0.55rem, 2.2vw, 1rem);
    overflow: hidden;
    background: var(--surface);
    border: 2px solid #fff;
    border-radius: clamp(0.9rem, 2.5vw, 1.35rem);
    outline: 1px solid color-mix(in srgb, var(--text) 30%, transparent);
    box-shadow: var(--shadow);
    container-type: size;
}

.ttt-game-content {
    display: grid;
    width: 100%;
    height: 100%;
    grid-template-rows: auto auto minmax(0, 1fr) auto;
    align-items: center;
    gap: clamp(0.3rem, 1.1vw, 0.55rem);
    transition: filter 0.25s ease;
}

.ttt-game.is-choosing .ttt-game-content {
    filter: blur(5px);
    pointer-events: none;
    user-select: none;
}

.ttt-mode-overlay[hidden] {
    display: none !important;
}

.ttt-mode-overlay {
    position: absolute;
    z-index: 5;
    inset: 0;
    display: grid;
    place-items: center;
    padding: clamp(0.75rem, 4vw, 1.5rem);
}

.ttt-mode-dialog {
    width: min(100%, 27rem);
    padding: clamp(1rem, 4vw, 1.6rem);
    text-align: center;
    background: color-mix(in srgb, var(--bg) 96%, transparent);
    border: 1px solid var(--card-border);
    border-radius: 1rem;
    box-shadow: var(--shadow);
}

.ttt-mode-dialog h2 {
    margin-bottom: 0.35rem;
    font-size: clamp(1.25rem, 4vw, 1.7rem);
    white-space: normal;
}

.ttt-mode-dialog > p {
    font-size: clamp(0.72rem, 2vw, 0.85rem);
}

.ttt-mode-options {
    margin-top: clamp(0.65rem, 2vw, 1rem);
}

.ttt-mode-button {
    min-height: clamp(4.4rem, 13cqh, 6rem);
    padding: 0.65rem;
}

.ttt-status {
    min-height: 1.4rem;
    margin: 0;
}

.ttt-actions {
    width: 100%;
    margin: 0;
}

.ttt-board {
    width: 100cqh;
    width: min(100%, calc(100cqh - 8.5rem));
    max-width: 100%;
    justify-self: center;
    align-self: center;
    aspect-ratio: 1;
}

.ttt-game-footer {
    width: 100%;
    margin: 0;
}

@media (max-width: 520px) {
    .ttt-game {
        width: min(100%, 78dvh);
        padding: 0.55rem;
    }

    .ttt-mode-options {
        grid-template-columns: 1fr;
        gap: 0.45rem;
        margin-top: 0.65rem;
    }

    .ttt-mode-button {
        min-height: 4rem;
        gap: 0.15rem;
        padding: 0.5rem;
    }

    .ttt-mode-name {
        font-size: 0.9rem;
    }

    .ttt-mode-description {
        font-size: 0.68rem;
    }

    .ttt-board {
        width: min(100%, calc(100cqh - 7.5rem));
        gap: 0.4rem;
    }

    .ttt-action {
        min-height: 2.45rem;
        padding: 0.4rem 0.7rem;
    }

    .ttt-mode-label,
    .ttt-text-button {
        font-size: 0.68rem;
    }
}

@media (prefers-reduced-motion: reduce) {
    .ttt-game-content {
        transition: none;
    }
}

/* Keep the whole game visible without scrolling, with a bright arcade-board look. */
:root {
    --ttt-game-bg: #fff;
    --ttt-game-ink: #111;
    --ttt-game-muted: #555;
    --ttt-game-border: #dedede;
    --ttt-game-hover: #f7f7f7;
    --ttt-game-disabled: #f5f5f5;
    --ttt-game-overlay: rgba(255, 255, 255, 0.88);
    --ttt-game-shadow: 0 12px 36px rgba(0, 0, 0, 0.12);
    --ttt-choice-bg: #111;
    --ttt-choice-ink: #fff;
}

body.tic-tac-toe-page {
    display: flex;
    min-height: 100vh;
    min-height: 100dvh;
    flex-direction: column;
}

body.tic-tac-toe-page > #header,
body.tic-tac-toe-page > #footer {
    flex: 0 0 auto;
}

@media (prefers-color-scheme: dark) {
    :root {
        --ttt-game-bg: #101010;
        --ttt-game-ink: #f5f5f5;
        --ttt-game-muted: #b4b4b4;
        --ttt-game-border: #393939;
        --ttt-game-hover: #1c1c1c;
        --ttt-game-disabled: #191919;
        --ttt-game-overlay: rgba(255, 255, 255, 0.07);
        --ttt-game-shadow: 0 12px 36px rgba(0, 0, 0, 0.48);
        --ttt-choice-bg: #fff;
        --ttt-choice-ink: #111;
    }
}

.ttt-main {
    width: min(1000px, calc(100% - 1.25rem));
    flex: 1 0 auto;
    padding: 1.35rem 0 1rem;
}

.ttt-intro {
    margin-bottom: clamp(0.45rem, 1.4dvh, 0.9rem);
}

.ttt-intro h1 {
    margin-bottom: 0.2rem;
    font-size: clamp(1.45rem, 4.8vw, 2.2rem);
}

.ttt-intro p {
    font-size: clamp(0.78rem, 2vw, 0.92rem);
}

.ttt-game {
    width: min(100%, 620px, 72dvh, calc(100dvh - 16rem));
    min-width: 0;
    background: var(--ttt-game-bg);
    color: var(--ttt-game-ink);
    border-color: #fff;
    outline-color: color-mix(in srgb, var(--ttt-game-ink) 22%, transparent);
    box-shadow: var(--ttt-game-shadow);
}

.ttt-mode-dialog {
    background: color-mix(in srgb, var(--ttt-game-bg) 97%, transparent);
    border-color: var(--ttt-game-border);
    color: var(--ttt-game-ink);
    box-shadow: var(--ttt-game-shadow);
}

.ttt-mode-dialog > p,
.ttt-mode-description,
.ttt-mode-label {
    color: var(--ttt-game-muted);
}

.ttt-mode-button {
    color: var(--ttt-choice-ink);
    background: var(--ttt-choice-bg);
    border-color: var(--ttt-choice-bg);
}

.ttt-mode-button .ttt-mode-description {
    color: color-mix(in srgb, var(--ttt-choice-ink) 78%, transparent);
}

.ttt-mode-button:hover {
    border-color: var(--ttt-game-muted);
    box-shadow: var(--ttt-game-shadow);
}

.ttt-status {
    color: var(--ttt-game-ink);
}

.ttt-action {
    color: var(--ttt-game-ink);
    background: var(--ttt-game-bg);
    border: 1px solid var(--ttt-game-border);
    border-radius: 0.65rem;
}

.ttt-action:disabled {
    color: var(--ttt-game-muted);
    background: var(--ttt-game-disabled);
}

.ttt-board {
    gap: clamp(0.25rem, 1.1cqh, 0.55rem);
}

.ttt-cell {
    color: var(--ttt-game-ink);
    background: var(--ttt-game-bg);
    border-color: var(--ttt-game-border);
}

.ttt-cell:hover:not(:disabled) {
    background: var(--ttt-game-hover);
}

.ttt-paused-overlay {
    color: var(--ttt-game-ink);
    background: color-mix(in srgb, var(--ttt-game-bg) 16%, transparent);
    backdrop-filter: blur(8px) saturate(140%);
    -webkit-backdrop-filter: blur(8px) saturate(140%);
}

.ttt-text-button {
    color: var(--ttt-game-muted);
}

.ttt-text-button:hover {
    color: var(--ttt-game-ink);
}

body.tic-tac-toe-page .site-footer {
    margin-top: 0;
    padding: 1rem 1.25rem;
}

@media (max-width: 520px) {
    .ttt-main {
        width: calc(100% - 1rem);
        padding-top: 1rem;
        padding-bottom: 0.6rem;
    }

    .ttt-game {
        width: min(100%, 72dvh, calc(100dvh - 15rem));
    }
}

/* Five by five board and a winning stroke that fits any four-cell run. */
.ttt-mode-options[hidden] {
    display: none !important;
}

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

.ttt-picker-back {
    grid-column: 1 / -1;
    justify-self: center;
}

.ttt-board {
    grid-template-columns: repeat(var(--ttt-grid-size, 5), minmax(0, 1fr));
    grid-template-rows: repeat(var(--ttt-grid-size, 5), minmax(0, 1fr));
    gap: clamp(0.2rem, 0.75cqh, 0.45rem);
}

.ttt-cell[hidden] {
    display: none !important;
}

.ttt-cell {
    font-size: clamp(1rem, 7.5cqh, 3rem);
    border-radius: clamp(0.35rem, 1cqh, 0.7rem);
}

.ttt-win-line {
    height: 5px;
}

.ttt-intro {
    animation: ttt-interface-enter 560ms cubic-bezier(0.2, 0.75, 0.25, 1) both;
}

.ttt-game {
    animation: ttt-interface-enter 680ms cubic-bezier(0.2, 0.75, 0.25, 1) 90ms both;
}

body.tic-tac-toe-page > #footer {
    animation: ttt-interface-enter 560ms cubic-bezier(0.2, 0.75, 0.25, 1) 160ms both;
}

@keyframes ttt-interface-enter {
    from {
        opacity: 0;
        transform: translateY(18px) scale(0.985);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

@media (max-width: 520px) {
    .ttt-difficulty-options {
        grid-template-columns: 1fr;
    }

    .ttt-cell {
        font-size: clamp(1rem, 7.5cqh, 2.25rem);
    }
}

@media (prefers-reduced-motion: reduce) {
    .ttt-intro,
    .ttt-game,
    body.tic-tac-toe-page > #footer {
        animation: none !important;
    }
}