/* ベース設定：タイトル画面に寄せた全体テーマ */
    :root {
        --seki-s: #00d8ff;
        --seki-e: #34f78d;
        --seki-k: #ff355e;
        --seki-bg: #030a15;
        --seki-bg-deep: #02060e;
        --seki-bg-mid: #050d19;
        --seki-bg-bright: #0e2342;
        --seki-text-main: #eff6ff;
        --seki-text-sub: #d9ebff;
        --seki-text-muted: #9cb3c9;
        --seki-danger: #ef5350;
        --seki-warning: #ffeb3b;
        --seki-success: #34f78d;
        --seki-card-border: rgba(165, 205, 255, 0.35);
        --seki-panel-border: rgba(0, 216, 255, 0.32);
        --seki-panel-bg: rgba(4, 11, 23, 0.76);
        --seki-panel-bg-soft: rgba(6, 16, 32, 0.55);
        --seki-radius-sm: 8px;
        --seki-radius-md: 12px;
        --seki-radius-lg: 18px;
        --seki-shadow-soft: 0 8px 20px rgba(0, 0, 0, 0.36);
        --seki-shadow-panel: 0 18px 40px rgba(0, 0, 0, 0.52);
        --seki-shadow-glow: 0 0 26px rgba(0, 216, 255, 0.22);
        --seki-transition-fast: 0.2s ease;
        --seki-transition-mid: 0.3s ease;
        --seki-game-max-width: 800px;
        --seki-side-gap: 12px;
        --seki-side-left-width: 260px;
        --seki-side-right-width: 320px;
        --seki-desktop-panel-bg: linear-gradient(155deg, rgba(6, 16, 32, 0.9), rgba(4, 11, 23, 0.86));
        --seki-desktop-panel-border: 1px solid rgba(0, 216, 255, 0.34);
        --seki-desktop-panel-shadow: 0 10px 30px rgba(0,0,0,0.8), 0 0 22px rgba(0, 216, 255, 0.18);
        --seki-desktop-header-bg: rgba(8, 26, 48, 0.42);
        --seki-desktop-header-border: 1px solid rgba(0, 216, 255, 0.28);
        --seki-desktop-header-text: #a8e9ff;
        --seki-desktop-header-font: var(--font-ui);
        --seki-desktop-header-pad: 10px 12px 8px;
    }

    html {
        min-height: 100%;
        background: var(--seki-bg-deep);
    }

    body {
        font-family: var(--font-ui);
        font-synthesis: none;
        font-synthesis-weight: none;
        background:
            radial-gradient(circle at 18% 14%, rgba(0, 216, 255, 0.14), transparent 36%),
            radial-gradient(circle at 82% 24%, rgba(255, 53, 94, 0.11), transparent 34%),
            radial-gradient(circle at 70% 78%, rgba(52, 247, 141, 0.08), transparent 36%),
            radial-gradient(circle at 50% 110%, #0e2342 0%, #050d19 48%, #02060e 100%);
        background-attachment: fixed;
        color: var(--seki-text-main);
        margin: 0;
        text-align: center;
        user-select: none;
        -webkit-tap-highlight-color: transparent;
        min-height: 100vh;
        min-height: 100dvh;
        min-height: var(--app-height, 100dvh);
        overflow-y: auto;
        overflow-x: hidden;
        display: flex;
        flex-direction: column;
    }
    body.desktop-side-mode {
        --seki-side-panel-width: calc((100vw - var(--seki-game-max-width, 800px)) / 2);
    }

    @media (max-width: 1240px) {
    body {
        --seki-game-max-width: 700px;
    }
    }

    /* 共通レイアウト */
    #game-screen {
        position: relative;
        isolation: isolate;
        padding: 0;
        margin: 0 auto;
        width: 100%;
        max-width: var(--seki-game-max-width, 800px);
        height: auto;
        min-height: 100vh;
        min-height: 100dvh;
        min-height: var(--app-height, 100dvh);
        display: flex;
        flex-direction: column;
        overflow: visible;
        background: linear-gradient(155deg, rgba(6, 16, 32, 0.5), rgba(2, 8, 18, 0.35));
        border-left: 1px solid rgba(0, 216, 255, 0.11);
        border-right: 1px solid rgba(0, 216, 255, 0.11);
        box-shadow: 0 0 40px rgba(0, 0, 0, 0.35);
        max-width: 800px;
    }
    body.desktop-side-mode #game-screen {
        width: 100vw;
        max-width: 100vw;
        margin: 0;
        height: var(--app-height, 100dvh);
        min-height: var(--app-height, 100dvh);
        max-height: var(--app-height, 100dvh);
        display: grid;
        grid-template-columns:
            var(--seki-side-panel-width)
            minmax(0, var(--seki-game-max-width, 800px))
            var(--seki-side-panel-width);
        grid-template-rows: 42px minmax(0, 1fr);
        align-content: stretch;
        overflow: hidden;
        border-left: none;
        border-right: none;
    }
    #game-screen::before,
    #game-screen::after {
        content: "";
        position: absolute;
        inset: 0;
        pointer-events: none;
        z-index: -1;
    }
    #game-screen::before {
        background:
            linear-gradient(rgba(45, 100, 190, 0.11) 1px, transparent 1px),
            linear-gradient(90deg, rgba(45, 100, 190, 0.11) 1px, transparent 1px);
        background-size: 42px 42px;
        opacity: 0.45;
        animation: gameGridShift 22s linear infinite;
    }
    #game-screen::after {
        background: repeating-linear-gradient(
            to bottom,
            rgba(255, 255, 255, 0.026) 0px,
            rgba(255, 255, 255, 0.026) 1px,
            rgba(0, 0, 0, 0) 1px,
            rgba(0, 0, 0, 0) 4px
        );
        opacity: 0.24;
    }
    #header-info {
        flex: 0 0 42px;
        padding: 8px 10px;
    }
    body.desktop-side-mode #header-info.seki-topbar {
        grid-column: 1 / -1;
        grid-row: 1;
        width: 100%;
        max-width: none;
        box-sizing: border-box;
        margin: 0;
        padding-left: 16px;
        padding-right: 16px;
        z-index: 130;
        background: var(--seki-desktop-header-bg);
        border-bottom: var(--seki-desktop-header-border);
        color: var(--seki-desktop-header-text);
        font-family: var(--seki-desktop-header-font);
    }
    body.desktop-side-mode #game-table {
        grid-column: 2;
        grid-row: 2;
        width: 100%;
        min-width: 0;
        min-height: 0;
    }
    .hidden { display: none !important; }
    .seki-topbar {
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 0 10px;
        font-size: 12px;
        height: 42px;
        border-bottom: 1px solid rgba(0, 216, 255, 0.22);
        background: linear-gradient(180deg, rgba(0, 0, 0, 0.28), rgba(0, 0, 0, 0.12));
        backdrop-filter: blur(6px);
    }
    .seki-topbar-actions {
        display: flex;
        gap: 8px;
        align-items: center;
    }
    .seki-msg {
        margin-top: 2px;
        color: var(--seki-warning);
        font-weight: 400;
        font-size: 13px;
        letter-spacing: var(--font-ui-emphasis-tracking);
        height: 18px;
        line-height: 18px;
        white-space: nowrap;
        text-shadow: 0 0 8px rgba(255, 235, 59, 0.3);
    }
    .seki-controls {
        margin-top: 5px;
    }
    .seki-controls .seki-btn {
        min-width: 84px;
    }
    .seki-btn {
        border: 1px solid var(--seki-card-border);
        border-radius: 16px;
        background: linear-gradient(135deg, rgba(4, 14, 30, 0.95), rgba(8, 22, 44, 0.92));
        color: var(--seki-text-main);
        font-family: var(--font-ui);
        font-size: 13px;
        letter-spacing: var(--font-ui-emphasis-tracking);
        text-shadow: var(--font-ui-emphasis-shadow);
        font-weight: 700;
        padding: 5px 12px;
        cursor: pointer;
        box-shadow: 0 3px 10px rgba(0, 0, 0, 0.35);
        transition: transform var(--seki-transition-fast), box-shadow var(--seki-transition-fast), border-color var(--seki-transition-fast), filter var(--seki-transition-fast);
    }
    .seki-btn:hover:not(:disabled) {
        transform: translateY(-1px);
        border-color: rgba(0, 216, 255, 0.66);
        box-shadow: 0 6px 16px rgba(0, 0, 0, 0.45), 0 0 14px rgba(0, 216, 255, 0.2);
    }
    .seki-btn:active:not(:disabled) {
        transform: translateY(1px);
    }
    .seki-btn:disabled,
    .seki-btn.is-disabled {
        background: rgba(84, 99, 118, 0.85);
        border-color: rgba(132, 147, 168, 0.7);
        color: rgba(239, 246, 255, 0.7);
        cursor: not-allowed;
        box-shadow: none;
        transform: none;
        opacity: 0.78;
    }
    .seki-btn-mini {
        font-size: 12px;
        padding: 4px 9px;
    }
    .seki-btn-host {
        padding: 5px 12px;
        font-size: 15px;
        display: flex;
        align-items: center;
        border-radius: 18px;
    }
    .seki-btn-gold {
        background: linear-gradient(135deg, #bd8b14, #fbc02d 52%, #ffe082);
        color: #2f2214;
        border-color: rgba(255, 230, 156, 0.62);
    }
    .seki-btn-accent {
        background: linear-gradient(135deg, #0f314d, #166d98 46%, #00d8ff);
        color: #effbff;
        border-color: rgba(0, 216, 255, 0.65);
    }
    .seki-btn-danger {
        background: linear-gradient(135deg, #7c132a, #c21e44 46%, #ff355e);
        border-color: rgba(255, 143, 166, 0.75);
        color: #fff5f8;
    }
    .seki-btn-soft {
        background: linear-gradient(135deg, #2c3b54, #546e7a);
        border-color: rgba(197, 222, 255, 0.4);
    }
    .seki-overlay {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        z-index: 9999;
        display: none;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        pointer-events: none;
        color: var(--seki-text-main);
        background: rgba(1, 6, 14, 0.88);
        backdrop-filter: blur(4px);
    }
    #asset-loading-screen {
        position: fixed;
        inset: 0;
        z-index: 10050;
        display: flex;
        align-items: center;
        justify-content: center;
        background: rgba(2, 8, 18, 0.9);
        backdrop-filter: blur(5px);
        padding: 20px;
        box-sizing: border-box;
    }
    #asset-loading-screen.hidden {
        display: none !important;
    }
    #asset-loading-panel {
        width: min(92vw, 520px);
        border: 1px solid rgba(0, 216, 255, 0.4);
        border-radius: 14px;
        padding: 20px 18px;
        box-shadow: var(--seki-shadow-panel), 0 0 20px rgba(0, 216, 255, 0.22);
        background:
            linear-gradient(155deg, rgba(6, 16, 32, 0.95), rgba(4, 11, 23, 0.9)),
            radial-gradient(circle at 14% 16%, rgba(0, 216, 255, 0.13), transparent 42%);
    }
    #asset-loading-panel h3 {
        margin: 0 0 10px;
        font-size: 18px;
        color: #dff6ff;
        letter-spacing: 0.08em;
        text-shadow:
            0 0 6px rgba(0, 216, 255, 0.45),
            0 0 14px rgba(52, 247, 141, 0.28);
        line-height: 1.35;
        animation: sekiLoadingPulse 2.2s ease-in-out infinite alternate;
    }
    #asset-loading-panel h3 .seki-loading-sub {
        display: block;
        margin-top: 3px;
        font-size: 12px;
        color: #9ce8ff;
        letter-spacing: 0.14em;
    }
    @keyframes sekiLoadingPulse {
        from { filter: brightness(0.88); opacity: 0.9; }
        to { filter: brightness(1.08); opacity: 1; }
    }
    #asset-loading-text {
        margin: 0 0 8px;
        font-size: 14px;
        color: #cfe5f8;
        letter-spacing: var(--font-ui-emphasis-tracking);
    }
    #asset-loading-progress-track {
        width: 100%;
        height: 12px;
        border-radius: 999px;
        overflow: hidden;
        background: rgba(120, 145, 171, 0.35);
        border: 1px solid rgba(164, 194, 225, 0.38);
    }
    #asset-loading-bar {
        width: 0%;
        height: 100%;
        background: linear-gradient(90deg, #00d8ff, #34f78d);
        transition: width 0.2s ease;
    }
    #asset-loading-current {
        margin: 9px 0 0;
        font-size: 12px;
        color: #9ec3df;
        min-height: 1.2em;
        word-break: break-all;
    }
    #asset-loading-failed {
        margin-top: 10px;
        font-size: 12px;
        text-align: left;
        border: 1px solid rgba(255, 152, 0, 0.35);
        background: rgba(45, 28, 6, 0.5);
        border-radius: 10px;
        padding: 8px 10px;
        color: #ffe3c0;
    }
    #asset-loading-failed ul {
        margin: 6px 0 0;
        padding-left: 18px;
    }
    #asset-loading-actions {
        margin-top: 12px;
        display: flex;
        justify-content: flex-end;
        gap: 8px;
    }
    #asset-loading-retry-btn,
    #asset-loading-continue-btn {
        border: 1px solid var(--seki-card-border);
        border-radius: 16px;
        background: linear-gradient(135deg, rgba(4, 14, 30, 0.95), rgba(8, 22, 44, 0.92));
        color: var(--seki-text-main);
        font-family: var(--font-ui);
        font-size: 13px;
        letter-spacing: var(--font-ui-emphasis-tracking);
        text-shadow: var(--font-ui-emphasis-shadow);
        font-weight: 700;
        padding: 6px 12px;
        cursor: pointer;
    }
    #asset-loading-retry-btn:hover,
    #asset-loading-continue-btn:hover {
        border-color: rgba(0, 216, 255, 0.75);
    }
    #asset-loading-continue-btn {
        background: linear-gradient(135deg, #0f314d, #166d98 46%, #00d8ff);
    }
    #boot-transition-screen {
        position: fixed;
        inset: 0;
        z-index: 10070;
        display: flex;
        align-items: center;
        justify-content: center;
        overflow: hidden;
        transform-origin: left center;
        background:
            radial-gradient(circle at 18% 20%, rgba(0, 216, 255, 0.28), transparent 34%),
            radial-gradient(circle at 82% 28%, rgba(255, 53, 94, 0.18), transparent 36%),
            linear-gradient(145deg, #020814 0%, #051326 46%, #081e35 100%);
        will-change: opacity, transform, filter, clip-path;
    }
    #boot-transition-screen.hidden {
        display: none !important;
    }
    #boot-transition-screen::before {
        content: "";
        position: absolute;
        inset: 0;
        pointer-events: none;
        background: repeating-linear-gradient(
            to bottom,
            rgba(255, 255, 255, 0.04) 0px,
            rgba(255, 255, 255, 0.04) 1px,
            rgba(0, 0, 0, 0) 1px,
            rgba(0, 0, 0, 0) 4px
        );
        opacity: 0.32;
    }
    #boot-transition-screen::after {
        content: "";
        position: absolute;
        inset: 0;
        pointer-events: none;
        opacity: 0.06;
        mix-blend-mode: screen;
        background:
            radial-gradient(circle at 17% 28%, rgba(0, 216, 255, 0.35), transparent 38%),
            radial-gradient(circle at 76% 62%, rgba(52, 247, 141, 0.24), transparent 34%),
            repeating-linear-gradient(
                95deg,
                rgba(255, 255, 255, 0.16) 0 2px,
                rgba(0, 0, 0, 0.08) 2px 5px,
                rgba(255, 53, 94, 0.16) 5px 7px,
                rgba(0, 0, 0, 0.06) 7px 11px
            );
        background-size: 100% 100%, 100% 100%, 240px 100%;
        background-position: center, center, 0 0;
        will-change: opacity, transform, background-position, filter, clip-path;
    }
    #boot-transition-screen.is-wiping {
        animation: sekiBootNoiseOut 900ms steps(14, end) forwards;
    }
    #boot-transition-screen.is-wiping::after {
        opacity: 0.72;
        animation: sekiBootNoiseFlicker 120ms steps(2, end) infinite;
    }
    #boot-transition-title {
        position: relative;
        z-index: 1;
        margin: 0;
        text-align: center;
        font-family: var(--font-ui);
        font-size: clamp(40px, 9vw, 98px);
        letter-spacing: 0.12em;
        color: #e9fbff;
        text-shadow:
            0 0 10px rgba(0, 216, 255, 0.55),
            0 0 26px rgba(52, 247, 141, 0.35),
            0 0 48px rgba(0, 216, 255, 0.18);
        padding: 0 18px;
    }
    #boot-transition-title.is-active {
        animation: sekiBootTitlePulse 0.55s ease-in-out infinite alternate;
    }
    #boot-transition-screen.is-wiping #boot-transition-title {
        text-shadow:
            0 0 9px rgba(0, 216, 255, 0.4),
            0 0 20px rgba(52, 247, 141, 0.28),
            0 0 36px rgba(255, 53, 94, 0.24);
    }
    @keyframes sekiBootNoiseOut {
        0% {
            opacity: 1;
            filter: contrast(1) saturate(1);
            clip-path: inset(0 0 0 0);
            transform: translate3d(0, 0, 0) scale(1);
        }
        20% {
            opacity: 0.94;
            clip-path: inset(0 0 0 0);
            transform: translate3d(3px, -1px, 0) scale(1.002);
        }
        40% {
            opacity: 0.84;
            clip-path: inset(3% 0 6% 0);
            transform: translate3d(-3px, 2px, 0) scale(1.003);
            filter: contrast(1.16) saturate(1.06);
        }
        58% {
            opacity: 0.6;
            clip-path: inset(11% 0 17% 0);
            transform: translate3d(4px, -3px, 0) scale(0.997);
            filter: contrast(1.26) saturate(1.12);
        }
        76% {
            opacity: 0.35;
            clip-path: inset(30% 0 40% 0);
            transform: translate3d(-4px, 3px, 0) scale(0.993);
            filter: contrast(1.32) saturate(1.2);
        }
        100% {
            opacity: 0;
            clip-path: inset(48% 0 52% 0);
            transform: translate3d(0, 0, 0) scale(0.985);
            filter: contrast(0.82) saturate(0.74);
        }
    }
    @keyframes sekiBootNoiseFlicker {
        0% {
            opacity: 0.28;
            transform: translate3d(0, 0, 0);
            background-position: center, center, 0 0;
        }
        25% {
            opacity: 0.54;
            transform: translate3d(-2px, 1px, 0);
            background-position: center, center, 55px 0;
        }
        50% {
            opacity: 0.4;
            transform: translate3d(2px, -2px, 0);
            background-position: center, center, -60px 0;
        }
        75% {
            opacity: 0.66;
            transform: translate3d(-3px, 2px, 0);
            background-position: center, center, 95px 0;
        }
        100% {
            opacity: 0.3;
            transform: translate3d(1px, -1px, 0);
            background-position: center, center, -40px 0;
        }
    }
    @keyframes sekiBootTitlePulse {
        from { filter: brightness(0.9); transform: scale(0.995); }
        to { filter: brightness(1.16); transform: scale(1.01); }
    }
    @keyframes sekiBootFadeOut {
        0% { opacity: 1; }
        100% { opacity: 0; }
    }