/* ========== Pop Chain — shared palette & typography ========== */
:root {
    --shadow: #3d342d;
    --shadow-rgb: 61, 52, 45;
    --cream: #fffff5;
    --pop-ice: #5ed4ff;
    --pop-cyan: #47d1ff;
    --pop-cyan-mid: #00a3ff;
    --pop-cyan-deep: #003366;
    --p1: #00a3ff;
    --p1-dark: #003366;
    --p2: #e54848;
    --p2-dark: #8b1c1c;
    --home-text: #3d342d;
    --home-text-muted: #8a7b72;
    --home-chip-idle: #fafffcf8;
    --home-input-fill: #fffffff5;
    --frame-rim: #e8e4e0;
    --grid-line: #c5bdb5;
    --board-well-top: #f5f1ed;
    --board-well-bottom: #e9e5e0;
    --board-tile-a: #f0ece8;
    --board-tile-b: #e8e4df;
    --cta-orange-top: #ff9a52;
    --cta-orange-mid: #e66e18;
    --cta-orange-bottom: #c4540e;
    --cta-orange-deep: #943a0a;
    --p2-sparkle-tint: #ffe0dc;
    --font-ui: 'Poppins', system-ui, sans-serif;
    --font-display: 'Fredoka', system-ui, sans-serif;
    --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
    --spacing: 12px;
    --popup-width: 340px;
    --popup-height: 440px;
    --p1-border-soft: rgba(0, 163, 255, 0.42);
    --p2-border-soft: rgba(139, 28, 28, 0.38);
    --white-rim: rgba(255, 255, 255, 0.85);
    --p1-pill-grad: linear-gradient(180deg, var(--pop-ice) 0%, var(--p1) 45%, var(--p1-dark) 100%);
    --p1-pill-gloss: linear-gradient(180deg, rgba(71, 209, 255, 0.35) 0%, transparent 100%);
}

/* ========== Page: bg.png + cream warmth ========== */
body {
    margin: 0;
    background-color: var(--cream);
    background-image: url('../img/bg.png');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    color: var(--home-text);
    font-family: var(--font-ui);
    font-weight: 500;
    overflow: hidden;
    touch-action: none;
    min-height: 100vh;
    min-height: 100dvh;
    width: 100vw;
    user-select: none;
    position: relative;
}

body::before {
    content: '';
    position: fixed;
    inset: 0;
    background: linear-gradient(180deg, rgba(255, 253, 245, 0.55) 0%, rgba(245, 241, 237, 0.4) 100%);
    pointer-events: none;
    z-index: 0;
}

/* ========== Viewport: full screen, game centered ========== */
#app-viewport {
    position: fixed;
    inset: 0;
    width: 100%;
    height: 100%;
    min-width: 100vw;
    min-height: 100vh;
    min-height: 100dvh;
    display: flex;
    align-items: center;
    justify-content: center;
    box-sizing: border-box;
    padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left);
    z-index: 1;
}

/* ========== Game container: centered on screen, transparent so bg.png shows ========== */
#game-container {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    width: 95vmin;
    max-width: 540px;
    height: 95vmin;
    max-height: 100vh;
    max-height: 100dvh;
    min-height: 420px;
    margin: auto;
    background: transparent;
    box-sizing: border-box;
}

/* ========== Corner buttons: game-style, match board theme ========== */
.corner-buttons {
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 100;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    justify-content: space-between;
}

/* Start screen is separate — hide corner buttons when start pop-up is visible */
body.start-screen-open .corner-buttons {
    display: none !important;
}

.corner-btn {
    pointer-events: auto;
    width: 44px;
    height: 44px;
    padding: 0;
    border: 2px solid var(--white-rim);
    border-radius: 12px;
    background: linear-gradient(180deg, var(--cta-orange-top) 0%, var(--cta-orange-mid) 45%, var(--cta-orange-bottom) 100%);
    color: #fff;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.2s var(--ease-out), box-shadow 0.2s var(--ease-out), filter 0.2s;
    box-shadow:
        0 4px 0 var(--cta-orange-deep),
        0 8px 20px rgba(var(--shadow-rgb), 0.35),
        inset 0 1px 0 rgba(255, 255, 255, 0.35);
    -webkit-tap-highlight-color: transparent;
}

.corner-btn:hover {
    filter: brightness(1.05);
    transform: scale(1.06);
    box-shadow:
        0 4px 0 var(--cta-orange-deep),
        0 10px 24px rgba(var(--shadow-rgb), 0.4),
        inset 0 1px 0 rgba(255, 255, 255, 0.45);
}

.corner-btn:active {
    transform: scale(0.96);
    box-shadow:
        0 2px 0 var(--cta-orange-deep),
        0 4px 12px rgba(var(--shadow-rgb), 0.35),
        inset 0 2px 4px rgba(0, 0, 0, 0.15);
}

.corner-btn svg {
    width: 22px;
    height: 22px;
    display: block;
    margin: auto;
    flex-shrink: 0;
    filter: drop-shadow(0 1px 1px rgba(0, 0, 0, 0.35));
}

/* Help icon (?) viewBox is small — scale to match other icons */
.corner-btn--help svg {
    transform: scale(1.3);
}

.corner-buttons .corner-btn--home {
    position: absolute;
    top: var(--spacing);
    left: var(--spacing);
}

.corner-buttons .corner-btn--reset {
    position: absolute;
    top: var(--spacing);
    right: calc(var(--spacing) + 50px);
}

.corner-buttons .corner-btn--help {
    position: absolute;
    top: var(--spacing);
    right: var(--spacing);
}

/* ========== Layout: header → board (centered in game container) ========== */
#ui-layer {
    position: relative;
    flex: 1 1 0;
    min-height: 0;
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    box-sizing: border-box;
    z-index: 1;
}

.game-header {
    position: relative;
    flex-shrink: 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: clamp(8px, 3vw, 16px);
    padding: 0;
    margin: var(--spacing);
    margin-bottom: clamp(12px, 4vw, 20px);
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
    background: transparent;
    border: none;
    box-shadow: none;
    pointer-events: none;
}

.game-header .player-badge {
    position: relative;
}

/* ========== Turn pills (TurnPlayerPill) ========== */
.player-badge {
    display: flex;
    align-items: center;
    gap: clamp(6px, 1.8vw, 10px);
    font-size: clamp(11px, 3vw, 14px);
    font-weight: 800;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    font-family: var(--font-ui);
    border-radius: 999px;
    padding: clamp(6px, 1.5vw, 9px) clamp(12px, 3vw, 18px);
    transition:
        transform 0.28s var(--ease-out),
        box-shadow 0.28s var(--ease-out),
        border-color 0.28s var(--ease-out),
        color 0.28s var(--ease-out),
        background 0.28s var(--ease-out);
    pointer-events: none;
    border: 2px solid var(--p1-border-soft);
    background: var(--home-chip-idle);
    color: var(--home-text-muted);
    box-shadow: 0 2px 8px rgba(var(--shadow-rgb), 0.12);
}

.player-badge--p2 {
    border-color: var(--p2-border-soft);
}

.player-badge.active {
    transform: scale(1.06);
    color: #fff;
}

.player-badge--p1.active {
    background: var(--p1);
    border-color: rgba(255, 255, 255, 0.9);
    box-shadow:
        0 3px 0 var(--p1-dark),
        0 8px 22px rgba(var(--shadow-rgb), 0.28),
        0 0 20px rgba(0, 163, 255, 0.35);
}

.player-badge--p2.active {
    background: var(--p2);
    border-color: rgba(255, 255, 255, 0.9);
    box-shadow:
        0 3px 0 var(--p2-dark),
        0 8px 22px rgba(var(--shadow-rgb), 0.28),
        0 0 18px rgba(229, 72, 72, 0.35);
}

.player-badge__label {
    text-shadow: none;
}

.player-badge.active .player-badge__label {
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.35);
}

.player-badge__sparkle {
    display: flex;
    align-items: center;
    opacity: 0;
    transform: scale(0.6);
    transition: opacity 0.25s var(--ease-out), transform 0.25s var(--ease-out);
}

.player-badge.active .player-badge__sparkle {
    opacity: 1;
    transform: scale(1);
}

.player-badge--p1 .player-badge__sparkle {
    color: var(--pop-ice);
    filter: drop-shadow(0 1px 1px rgba(0, 0, 0, 0.25));
}

.player-badge--p2 .player-badge__sparkle {
    color: var(--p2-sparkle-tint);
    filter: drop-shadow(0 1px 1px rgba(0, 0, 0, 0.3));
}

.player-badge .dot {
    width: clamp(9px, 2.6vw, 15px);
    height: clamp(9px, 2.6vw, 15px);
    border-radius: 50%;
    flex-shrink: 0;
    box-sizing: border-box;
}

.player-badge--p1 .dot {
    background: var(--p1);
    border: 2px solid rgba(255, 255, 255, 0.55);
    box-shadow: 0 2px 6px rgba(var(--shadow-rgb), 0.25);
}

.player-badge--p1:not(.active) .dot {
    opacity: 0.55;
}

.player-badge--p2 .dot {
    background: linear-gradient(135deg, #fff5f4 0%, var(--p2) 48%, var(--p2-dark) 100%);
    border: 2px solid rgba(255, 255, 255, 0.95);
    box-shadow: 0 2px 6px rgba(var(--shadow-rgb), 0.3);
}

.player-badge--p2:not(.active) .dot {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.5) 0%, var(--p2) 55%, var(--p2-dark) 100%);
    box-shadow: 0 1px 4px rgba(var(--shadow-rgb), 0.2);
}

.player-badge__sparkle svg {
    display: block;
    width: 14px;
    height: 14px;
}

/* ========== Board stage: inscribed square via container query ========== */
.board-stage {
    container-type: size;
    flex: 1 1 0;
    min-height: 0;
    min-width: 0;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 var(--spacing);
    margin: var(--spacing) 0;
    box-sizing: border-box;
}

/* ========== Game board frame (GameBoardFrame) ========== */
.board-wrapper {
    position: relative;
    flex: 0 0 auto;
    width: min(100cqw, 100cqh);
    height: min(100cqw, 100cqh);
    max-width: 100%;
    max-height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    box-sizing: border-box;
    padding: 6px;
    background: linear-gradient(180deg, var(--cta-orange-top) 0%, var(--cta-orange-mid) 45%, var(--cta-orange-bottom) 100%);
    border: 2px solid var(--white-rim);
    border-radius: 14px;
    box-shadow:
        0 16px 40px rgba(var(--shadow-rgb), 0.32),
        5px 8px 0 rgba(148, 58, 10, 0.45),
        inset 0 1px 0 rgba(255, 255, 255, 0.4);
}

@supports not (width: 1cqw) {
    .board-stage {
        container-type: normal;
    }

    .board-wrapper {
        width: 100%;
        max-width: 100%;
        aspect-ratio: 1;
        height: auto;
        max-height: min(100%, 85vmin);
    }
}

.board-wrapper::before {
    content: '';
    position: absolute;
    inset: 6px;
    border-radius: 10px;
    box-shadow: inset 0 0 0 3px rgba(255, 255, 255, 0.92);
    pointer-events: none;
    z-index: 1;
}

.board-wrapper::after {
    content: '';
    position: absolute;
    inset: 9px;
    border-radius: 8px;
    background: linear-gradient(180deg, var(--board-well-top) 0%, var(--board-well-bottom) 100%);
    box-shadow:
        inset 0 1px 0 rgba(255, 255, 255, 0.65),
        inset 0 4px 12px rgba(var(--shadow-rgb), 0.06);
    border: 1px solid rgba(197, 189, 181, 0.35);
    pointer-events: none;
    z-index: 0;
}

#canvas {
    position: relative;
    z-index: 1;
    display: block;
    width: 100%;
    height: 100%;
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
    cursor: pointer;
    pointer-events: auto;
    background: transparent;
    border-radius: 6px;
}

/* ========== Overlays: scrim + shells ========== */
.screen {
    display: flex;
    align-items: center;
    justify-content: center;
    pointer-events: auto;
    transition: opacity 0.3s;
    padding: 20px;
    box-sizing: border-box;
    background: rgba(0, 0, 0, 0.6);
    z-index: 50;
}

.pop-chain-scrim {
    background: rgba(0, 0, 0, 0.35);
}

/* Full-viewport overlay: covers entire screen, popup centered */
.screen--full {
    position: fixed;
    inset: 0;
    width: 100%;
    height: 100%;
    min-width: 100vw;
    min-height: 100vh;
    min-height: 100dvh;
    z-index: 110;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow-y: auto;
    overflow-x: hidden;
    padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left);
    box-sizing: border-box;
}

#screen-start {
    background-image:
        linear-gradient(180deg, rgba(255, 253, 245, 0.65) 0%, rgba(0, 0, 0, 0.22) 100%),
        url('../img/bg.png');
    background-size: cover;
    background-position: center;
    background-color: var(--cream);
}

.screen.hidden {
    opacity: 0;
    pointer-events: none;
}

#screen-over.pop-chain-scrim {
    background: rgba(0, 0, 0, 0.35);
}

/* How to play: fixed height, scroll */
.popup--help {
    width: min(var(--popup-width), calc(100% - 2 * var(--spacing)));
    max-width: calc(100vw - 2 * var(--spacing));
    min-height: var(--popup-height);
    height: var(--popup-height);
    max-height: var(--popup-height);
    overflow-y: auto;
    overflow-x: hidden;
    -webkit-overflow-scrolling: touch;
    /* Full-width column so title + CTA align to the same edges as the list */
    align-items: stretch;
}

.popup--help .pop-chain-overlay-shell__title {
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
    text-align: center;
    text-wrap: balance;
}

.popup--help .help-list {
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
}

/* Primary CTA: pill width fits label, centered; extra left padding offsets letter-spacing after last glyph */
.popup--help .pop-chain-primary-btn {
    display: inline-flex;
    align-self: center;
    align-items: center;
    justify-content: center;
    width: auto;
    max-width: none;
    box-sizing: border-box;
    text-align: center;
    padding-top: 20px;
    padding-bottom: 20px;
    padding-left: calc(40px + 0.16em);
    padding-right: 40px;
    position: relative;
    z-index: 1;
}

.help-list {
    list-style: none;
    padding: 0;
    margin: 0 0 24px 0;
    text-align: left;
    color: var(--home-text);
    font-size: 14px;
    font-weight: 500;
    line-height: 1.65;
}

.help-list li {
    margin-bottom: 10px;
    padding-left: 1.2em;
    position: relative;
}

.help-list li::before {
    content: "•";
    color: var(--p1);
    position: absolute;
    left: 0;
}

/* Default popup (overridden by shells) */
.popup {
    background: var(--home-chip-idle);
    border: 2px solid var(--p1-border-soft);
    border-radius: 16px;
    padding: 28px 32px;
    width: var(--popup-width);
    max-width: calc(100% - 40px);
    margin: auto;
    box-shadow: 0 16px 40px rgba(var(--shadow-rgb), 0.28);
    display: flex;
    flex-direction: column;
    align-items: center;
}

.pop-chain-overlay-shell {
    background: var(--home-chip-idle);
    border: 2px solid rgba(0, 163, 255, 0.42);
    box-shadow: 0 16px 44px rgba(var(--shadow-rgb), 0.3);
}

.pop-chain-overlay-shell__title {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: clamp(22px, 5.5vw, 28px);
    color: var(--pop-cyan-deep);
    margin: 0 0 16px 0;
    text-align: center;
    letter-spacing: 0.02em;
    line-height: 1.2;
    -webkit-text-fill-color: var(--pop-cyan-deep);
    background: none;
}

/* Game-over card (_GameOverPanel) */
.pop-chain-game-over {
    position: relative;
    border: none;
    background: linear-gradient(180deg, var(--board-well-top) 0%, var(--board-well-bottom) 100%);
    border-radius: 20px;
    padding: 32px 36px;
    overflow: hidden;
    box-shadow:
        0 20px 48px rgba(var(--shadow-rgb), 0.28),
        0 0 0 1px rgba(255, 255, 255, 0.5);
}

.pop-chain-game-over::before {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    height: 38%;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.55) 0%, transparent 100%);
    pointer-events: none;
    border-radius: 20px 20px 0 0;
}

.pop-chain-game-over.winner-p1 {
    box-shadow:
        0 22px 52px rgba(var(--shadow-rgb), 0.26),
        0 0 0 1px rgba(255, 255, 255, 0.55),
        0 12px 36px rgba(0, 51, 102, 0.22),
        0 8px 28px rgba(230, 110, 24, 0.12);
}

.pop-chain-game-over.winner-p2 {
    box-shadow:
        0 22px 52px rgba(var(--shadow-rgb), 0.28),
        0 0 0 1px rgba(255, 255, 255, 0.5),
        0 12px 36px rgba(139, 28, 28, 0.2),
        0 8px 28px rgba(230, 110, 24, 0.1);
}

.pop-chain-game-over__title {
    position: relative;
    z-index: 1;
    font-family: var(--font-display);
    font-weight: 600;
    font-size: clamp(22px, 6vw, 32px);
    letter-spacing: 0.08em;
    line-height: 1.15;
    text-align: center;
    text-transform: uppercase;
    margin: 0 0 20px 0;
}

.popup--start .logo-img {
    display: block;
    max-width: 100%;
    width: min(280px, 85vw);
    height: auto;
    object-fit: contain;
}

.popup--start .grid-size-select {
    display: grid !important;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 10px;
    width: 100%;
    max-width: 100%;
    align-items: stretch;
}

.popup--start .grid-size-option {
    width: 100%;
    min-width: 0;
}

.popup--start .pop-chain-overlay-shell__title {
    display: none;
}

.popup h1:not(.pop-chain-overlay-shell__title):not(.pop-chain-game-over__title) {
    font-family: var(--font-display);
    font-size: clamp(28px, 7vw, 34px);
    font-weight: 600;
    margin: 0 0 10px 0;
    color: var(--pop-cyan-deep);
    text-align: center;
    letter-spacing: 0.04em;
    line-height: 1.15;
}

.popup p {
    color: var(--home-text);
    margin-bottom: 24px;
    text-align: center;
    line-height: 1.65;
    font-size: 14px;
    font-weight: 500;
}

.popup p.tagline {
    font-style: normal;
    color: var(--home-text-muted);
    opacity: 1;
    letter-spacing: 0.01em;
}

.grid-size-select {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    justify-content: center;
    margin-bottom: 28px;
}

/* Game mode chips */
.grid-size-option {
    position: relative;
    box-sizing: border-box;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 3px;
    flex: 1 1 0;
    min-width: 0;
    background: var(--home-chip-idle);
    color: var(--home-text);
    border: 2px solid rgba(0, 163, 255, 0.4);
    padding: 12px 18px;
    font-size: clamp(9px, 2.4vw, 11px);
    font-family: var(--font-display);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    line-height: 1.15;
    cursor: pointer;
    transition:
        border-color 0.22s var(--ease-out),
        color 0.22s var(--ease-out),
        box-shadow 0.22s var(--ease-out),
        transform 0.18s var(--ease-out),
        background 0.22s var(--ease-out);
    border-radius: 999px;
    box-shadow: 0 2px 10px rgba(var(--shadow-rgb), 0.12);
    -webkit-tap-highlight-color: transparent;
}

.grid-size-option:hover {
    border-color: rgba(0, 163, 255, 0.55);
    box-shadow: 0 3px 12px rgba(var(--shadow-rgb), 0.14);
}

.grid-size-option:active {
    transform: scale(0.98);
    background: rgba(0, 163, 255, 0.12);
}

.grid-size-option.selected {
    overflow: hidden;
    background: var(--p1-pill-grad);
    border-color: var(--white-rim);
    color: #fff;
    box-shadow:
        0 4px 0 var(--p1-dark),
        0 10px 24px rgba(var(--shadow-rgb), 0.22),
        inset 0 1px 0 rgba(255, 255, 255, 0.35);
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.35);
}

.grid-size-option.selected::before {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    height: 55%;
    background: var(--p1-pill-gloss);
    pointer-events: none;
    border-radius: 999px 999px 0 0;
}

.grid-size-option__name {
    position: relative;
    z-index: 1;
}

.grid-size-option__dim {
    position: relative;
    z-index: 1;
    font-family: ui-monospace, 'SF Mono', 'Menlo', 'Consolas', monospace;
    font-size: 0.92em;
    font-weight: 700;
    letter-spacing: 0.06em;
    text-transform: none;
    opacity: 0.92;
}

.grid-size-option:not(.selected) .grid-size-option__dim {
    color: var(--home-text-muted);
}

.grid-size-option.selected .grid-size-option__dim {
    color: rgba(255, 255, 255, 0.92);
}

/* Secondary-style button (outline pill) */
.btn {
    position: relative;
    background: var(--home-chip-idle);
    color: var(--home-text);
    border: 2px solid rgba(0, 163, 255, 0.4);
    padding: 14px 40px;
    font-size: 15px;
    font-family: var(--font-ui);
    font-weight: 800;
    text-transform: none;
    letter-spacing: 0.04em;
    cursor: pointer;
    transition:
        background 0.2s var(--ease-out),
        border-color 0.2s var(--ease-out),
        box-shadow 0.2s var(--ease-out),
        transform 0.15s var(--ease-out);
    border-radius: 999px;
    box-shadow: 0 2px 12px rgba(var(--shadow-rgb), 0.1);
    -webkit-tap-highlight-color: transparent;
}

.btn:hover {
    border-color: rgba(0, 163, 255, 0.55);
    box-shadow: 0 4px 16px rgba(var(--shadow-rgb), 0.14);
}

.btn:active {
    transform: scale(0.98);
    background: rgba(0, 163, 255, 0.1);
}

/* PopChainPrimaryButton */
.btn--primary,
.pop-chain-primary-btn {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 15px;
    text-transform: uppercase;
    letter-spacing: 0.16em;
    color: #fff;
    border: 2px solid var(--white-rim);
    border-radius: 999px;
    padding: 15px 40px;
    background: var(--p1-pill-grad);
    box-shadow:
        0 4px 0 var(--p1-dark),
        0 10px 28px rgba(var(--shadow-rgb), 0.28);
    overflow: hidden;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
}

.btn--primary::before,
.pop-chain-primary-btn::before {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    height: 52%;
    background: var(--p1-pill-gloss);
    pointer-events: none;
    border-radius: 999px 999px 0 0;
}

.btn--primary,
.pop-chain-primary-btn {
    position: relative;
}

.btn--primary:hover,
.pop-chain-primary-btn:hover {
    filter: brightness(1.03);
    box-shadow:
        0 4px 0 var(--p1-dark),
        0 12px 32px rgba(var(--shadow-rgb), 0.32);
}

.btn--primary:active,
.pop-chain-primary-btn:active {
    transform: translateY(2px);
    box-shadow:
        0 2px 0 var(--p1-dark),
        0 6px 18px rgba(var(--shadow-rgb), 0.22);
}

.winner-text--p1 {
    color: var(--pop-cyan-deep);
    text-shadow: 0 2px 0 rgba(255, 255, 255, 0.4), 0 4px 18px rgba(0, 51, 102, 0.2);
}

.winner-text--p2 {
    color: var(--p2-dark);
    text-shadow: 0 2px 0 rgba(255, 255, 255, 0.35), 0 4px 18px rgba(139, 28, 28, 0.2);
}

.pop-chain-game-over .pop-chain-primary-btn {
    position: relative;
    z-index: 1;
    margin-top: 4px;
}

/* ========== Responsive ========== */

/* Small Mobile (≤480px) */
@media (max-width: 480px) {
    :root {
        --spacing: 8px;
        --popup-width: 300px;
        --popup-height: min(380px, calc(100dvh - 24px));
    }
    #game-container {
        width: 98vmin;
        max-width: none;
        height: 98vmin;
        min-height: 280px;
    }
    .corner-btn {
        width: 40px;
        height: 40px;
        border-radius: 8px;
    }
    .corner-btn svg {
        width: 20px;
        height: 20px;
    }
    .corner-buttons .corner-btn--home { top: var(--spacing); left: var(--spacing); }
    .corner-buttons .corner-btn--reset { top: var(--spacing); right: calc(var(--spacing) + 44px); }
    .corner-buttons .corner-btn--help { top: var(--spacing); right: var(--spacing); }
    .game-header {
        margin: var(--spacing);
        margin-bottom: 12px;
        gap: 10px;
    }
    .player-badge {
        padding: 8px 12px;
        font-size: 13px;
        letter-spacing: 0.12em;
    }
    .player-badge .dot {
        width: 10px;
        height: 10px;
    }
    .board-wrapper {
        padding: 5px;
    }
    .board-wrapper::before { inset: 5px; }
    .board-wrapper::after { inset: 8px; }
    .screen { padding: 12px; }
    .popup {
        padding: 20px 24px;
        width: min(var(--popup-width), calc(100% - 24px));
        max-width: calc(100% - 24px);
    }
    .popup h1 { font-size: clamp(22px, 6vw, 28px); }
    .popup p, .help-list { font-size: 13px; }
    .popup p.tagline { font-size: 12px; }
    .help-list { margin-bottom: 18px; }
    .help-list li { margin-bottom: 8px; }
    .popup--help { padding: 16px 20px; }
    .popup--help .help-list { line-height: 1.6; }
    .popup--help .btn { margin-top: 4px; }
    .grid-size-option {
        padding: 11px 14px;
        font-size: 12px;
    }
    .btn { padding: 12px 32px; font-size: 14px; }
    .popup--help .pop-chain-primary-btn {
        padding-top: 18px;
        padding-bottom: 18px;
        padding-left: calc(32px + 0.16em);
        padding-right: 32px;
    }
    .popup--start .logo-img { width: min(220px, 78vw); }
}

/* Mobile (481px–640px) */
@media (min-width: 481px) and (max-width: 640px) {
    :root {
        --spacing: 10px;
        --popup-width: 320px;
        --popup-height: min(400px, calc(100dvh - 32px));
    }
    #game-container {
        width: 96vmin;
        max-width: none;
        height: 96vmin;
        min-height: 320px;
    }
    .corner-btn {
        width: 42px;
        height: 42px;
    }
    .corner-buttons .corner-btn--reset { right: calc(var(--spacing) + 46px); }
    .game-header { margin-bottom: 14px; gap: 12px; }
    .player-badge {
        padding: 9px 14px;
        font-size: 14px;
        letter-spacing: 0.14em;
    }
    .player-badge .dot { width: 12px; height: 12px; }
    .board-wrapper { padding: 5px; }
    .board-wrapper::before { inset: 5px; }
    .board-wrapper::after { inset: 8px; }
    .screen { padding: 16px; }
    .popup {
        padding: 24px 28px;
        max-width: calc(100% - 32px);
    }
    .popup h1 { font-size: clamp(24px, 6.5vw, 30px); }
    .popup p, .help-list { font-size: 13px; }
    .grid-size-option { padding: 11px 16px; font-size: 13px; }
    .btn { padding: 13px 36px; font-size: 15px; }
    .popup--help .pop-chain-primary-btn {
        padding-top: 19px;
        padding-bottom: 19px;
        padding-left: calc(36px + 0.16em);
        padding-right: 36px;
    }
    .popup--start .logo-img { width: min(240px, 80vw); }
}

/* Tablet Portrait (641px–768px) */
@media (min-width: 641px) and (max-width: 768px) {
    :root { --spacing: 12px; --popup-width: 360px; --popup-height: min(420px, calc(100dvh - 40px)); }
    #game-container {
        width: 92vmin;
        max-width: 480px;
        height: 92vmin;
        min-height: 380px;
    }
    .game-header { margin-bottom: 18px; }
    .board-wrapper { padding: 5px; }
    .screen { padding: 20px; }
    .popup { padding: 26px 30px; }
    .popup h1 { font-size: clamp(26px, 5vw, 32px); }
}

/* Tablet Landscape (769px–1024px) */
@media (min-width: 769px) and (max-width: 1024px) {
    #game-container {
        width: 88vmin;
        max-width: 520px;
        height: 88vmin;
        min-height: 400px;
    }
    .game-header { margin-bottom: 20px; }
}

/* Desktop (≥1025px) */
@media (min-width: 1025px) {
    #game-container {
        width: 95vmin;
        max-width: 540px;
        height: 95vmin;
        min-height: 420px;
    }
}

/* Landscape Mobile (orientation: landscape) — mobile in landscape */
@media (orientation: landscape) and (max-width: 640px) {
    :root { --spacing: 8px; --popup-width: 320px; --popup-height: min(320px, calc(100dvh - 24px)); }
    #app-viewport { align-items: flex-start; padding-top: max(env(safe-area-inset-top), 6px); overflow-y: auto; }
    #game-container {
        width: 95vmin;
        max-width: min(540px, 90vw);
        height: auto;
        min-height: 0;
        max-height: none;
    }
    .game-header { margin: var(--spacing); margin-bottom: 10px; gap: 10px; }
    .player-badge { padding: 8px 12px; font-size: 13px; letter-spacing: 0.1em; }
    .player-badge .dot { width: 11px; height: 11px; }
    .board-stage {
        min-height: min(70vw, calc(100dvh - 100px));
    }
    .board-wrapper { padding: 5px; }
    .board-wrapper::before { inset: 5px; }
    .board-wrapper::after { inset: 8px; }
    .corner-btn { width: 40px; height: 40px; border-radius: 8px; }
    .corner-btn svg { width: 20px; height: 20px; }
    .corner-buttons .corner-btn--reset { right: calc(var(--spacing) + 44px); }
    .screen { padding: 14px; }
    .popup { padding: 18px 24px; max-width: min(400px, calc(100% - 24px)); }
    .popup h1 { font-size: clamp(22px, 5vh, 28px); }
    .popup p, .help-list { font-size: 12px; }
    .grid-size-option { padding: 10px 14px; font-size: 12px; }
    .btn { padding: 11px 28px; font-size: 13px; }
    .popup--help .pop-chain-primary-btn {
        padding-top: 17px;
        padding-bottom: 17px;
        padding-left: calc(28px + 0.16em);
        padding-right: 28px;
    }
    .popup--start .logo-img { width: min(200px, 55vw); }
}

/* Landscape Mobile: short viewport (phone in landscape, height ≤500px) */
@media (orientation: landscape) and (max-height: 500px) {
    :root { --spacing: 6px; --popup-width: 320px; --popup-height: min(280px, calc(100dvh - 24px)); }
    #app-viewport { align-items: flex-start; padding-top: max(env(safe-area-inset-top), 6px); overflow-y: auto; }
    #game-container {
        width: 95vmin;
        max-width: min(540px, 90vw);
        height: auto;
        min-height: 0;
        max-height: none;
    }
    .game-header {
        margin: var(--spacing);
        margin-bottom: 8px;
        gap: 10px;
    }
    .player-badge {
        padding: 6px 12px;
        font-size: 12px;
        letter-spacing: 0.1em;
    }
    .player-badge .dot { width: 10px; height: 10px; }
    .board-stage {
        min-height: min(65vw, calc(100dvh - 96px));
    }
    .board-wrapper { padding: 4px; }
    .board-wrapper::before { inset: 4px; }
    .board-wrapper::after { inset: 7px; }
    .corner-btn {
        width: 38px;
        height: 38px;
        border-radius: 8px;
    }
    .corner-btn svg { width: 18px; height: 18px; }
    .corner-buttons .corner-btn--home { top: var(--spacing); left: var(--spacing); }
    .corner-buttons .corner-btn--reset { top: var(--spacing); right: calc(var(--spacing) + 42px); }
    .corner-buttons .corner-btn--help { top: var(--spacing); right: var(--spacing); }
    .screen { padding: 12px; }
    .popup {
        padding: 16px 24px;
        max-width: min(400px, calc(100% - 24px));
    }
    .popup h1 { font-size: clamp(20px, 4vh, 26px); }
    .popup p, .help-list { font-size: 12px; margin-bottom: 12px; }
    .help-list { margin-bottom: 14px; }
    .popup--help { padding: 14px 20px; }
    .grid-size-option { padding: 10px 14px; font-size: 12px; }
    .btn { padding: 10px 28px; font-size: 13px; }
    .popup--help .pop-chain-primary-btn {
        padding-top: 16px;
        padding-bottom: 16px;
        padding-left: calc(28px + 0.16em);
        padding-right: 28px;
    }
    .popup--start .logo-img { width: min(180px, 50vw); }
}

/* Landscape Mobile — very short viewport (e.g. keyboard up) */
@media (orientation: landscape) and (max-height: 400px) {
    :root { --popup-height: min(240px, calc(100dvh - 16px)); }
    .game-header { margin-bottom: 6px; }
    .player-badge { padding: 5px 10px; font-size: 11px; }
    .board-wrapper { padding: 3px; }
    .board-wrapper::before { inset: 3px; }
    .board-wrapper::after { inset: 6px; }
    .popup { padding: 12px 20px; }
    .popup h1 { font-size: 18px; }
    .popup--help { padding: 10px 16px; }
    .popup--help .help-list { font-size: 11px; margin-bottom: 10px; }
    .popup--help .help-list li { margin-bottom: 6px; }
}