body, html {
            margin: 0; padding: 0;
            background-color: #050508; /* Dark base color */
            color: #ffffff;
            font-family: 'Inter', sans-serif;
            overflow-x: hidden;
            scrollbar-gutter: stable;
            scroll-behavior: smooth;
            user-select: none;
            -webkit-user-select: none;
            -moz-user-select: none;
            -ms-user-select: none;
        }

        body {
            /*
             * Hover atmosphere system
             * - concept-bg-opacity: ???????/???
             * - atmosphere-active-opacity: ?????????
             * - atmosphere-active-blur: ??/??????????
             * - atmosphere-active-blur-soft/strong: ???????/??????
             * - atmosphere-active-glow: ?????????
             */
            --concept-bg-opacity-1: 0.8;
            --concept-bg-opacity-2: 0.8;
            --concept-bg-opacity-3: 0.8;

            --atmosphere-active-opacity-1: 0.6;
            --atmosphere-active-blur-1: 12px;
            --atmosphere-active-blur-soft-1: 9px;
            --atmosphere-active-blur-strong-1: 17px;
            --atmosphere-active-glow-1: 0.18;

            --atmosphere-active-opacity-2: 0.5;
            --atmosphere-active-blur-2: 10px;
            --atmosphere-active-blur-soft-2: 7px;
            --atmosphere-active-blur-strong-2: 15px;
            --atmosphere-active-glow-2: 0.16;

            --atmosphere-active-opacity-3: 0.4;
            --atmosphere-active-blur-3: 8px;
            --atmosphere-active-blur-soft-3: 6px;
            --atmosphere-active-blur-strong-3: 12px;
            --atmosphere-active-glow-3: 0.14;
        }
        
        input, textarea {
            user-select: text !important;
            -webkit-user-select: text !important;
            -moz-user-select: text !important;
            -ms-user-select: text !important;
        }

        input:-webkit-autofill,
        input:-webkit-autofill:hover,
        input:-webkit-autofill:focus,
        textarea:-webkit-autofill,
        textarea:-webkit-autofill:hover,
        textarea:-webkit-autofill:focus {
            -webkit-text-fill-color: #ffffff !important;
            caret-color: #ffffff;
            box-shadow: 0 0 0 1000px rgba(0, 0, 0, 0.62) inset !important;
            transition: background-color 9999s ease-in-out 0s;
        }

        /* ??????:??????? 0,????? 10,?????? body ??????? */
        #glcanvas-container {
            position: fixed;
            top: 0; left: 0;
            width: 100vw; height: 100vh;
            z-index: 0; 
            pointer-events: none;
        }

        #content-wrapper {
            position: relative;
            z-index: 10;
            min-height: 100dvh;
        }

        #main-content,
        #contact-section {
            min-height: 100dvh;
            box-sizing: border-box;
        }

        ::-webkit-scrollbar { width: 6px; height: 6px; }
        ::-webkit-scrollbar-track { background: rgba(0, 0, 0, 0.2); }
        ::-webkit-scrollbar-thumb { background: rgba(255, 255, 255, 0.1); border-radius: 9999px; }
        ::-webkit-scrollbar-thumb:hover { background: rgba(255, 255, 255, 0.3); }

        .logo-pulse {
            width: 5px; height: 5px;
            background: #ffffff;
            border-radius: 50%;
            box-shadow: 0 0 10px #ffffff;
            animation: logo-glow 2s infinite alternate;
            display: inline-block;
        }

        #overlay-status {
            max-width: 320px;
            text-align: center;
            line-height: 1.9;
        }

        .overlay-primary {
            display: block;
            color: rgba(255, 255, 255, 0.82);
        }

        .overlay-secondary {
            display: block;
            margin-top: 0.45rem;
            font-size: 9px;
            letter-spacing: 0.18em;
            color: rgba(255, 255, 255, 0.36);
        }

        #intro-logo-main {
            position: relative;
            display: inline-block;
            line-height: 1;
        }

        #intro-logo-main .intro-logo-core {
            display: inline-grid;
            grid-auto-flow: column;
            column-gap: 0.3em;
            letter-spacing: 0;
        }

        #intro-logo-main .intro-logo-suffix {
            position: absolute;
            top: 0;
            left: calc(100% + 0.18em);
            letter-spacing: 0;
            font-size: 0.62em;
            font-weight: 500;
            opacity: 0.86;
            transform: translateY(-0.08em);
        }

        @keyframes logo-glow {
            from { opacity: 0.5; box-shadow: 0 0 3px #ffffff; }
            to { opacity: 1; box-shadow: 0 0 12px #ffffff; }
        }

        .perspective-1000 { perspective: 1000px; }
        .transform-style-preserve-3d { transform-style: preserve-3d; }
        .backface-hidden { backface-visibility: hidden; }
        .rotate-x-180 { transform: rotateX(180deg); }
        /* JS???????? - ???? CSS hover */
        .flip-inner.flipped { transform: rotateX(180deg); }
        .flip-inner {
            transform-origin: 50% 50%;
            will-change: transform;
        }

        .flip-inner > div {
            transform: translateZ(0);
            line-height: 1;
        }

        .flip-inner > .rotate-x-180 {
            transform: rotateX(180deg) translateZ(0);
        }
 
        /* ??????:???????,???????????? */
        .glass-card {
            background: transparent;
            backdrop-filter: none;
            -webkit-backdrop-filter: none;
            border: 1px solid transparent;
            box-shadow: none;
            position: relative;
            overflow: visible;
            aspect-ratio: 9 / 16;
            z-index: 1;
            opacity: 1;
            filter: brightness(1);
            transform: translateZ(0);
            will-change: opacity, filter;
            transition: opacity 900ms ease, filter 900ms ease;
        }

        .glass-card > div:first-child {
            flex: 1;
            display: flex;
            flex-direction: column;
            justify-content: center;
            min-height: 0;
        }

        /* ??????????/??;??????????? */
        .glass-card > div:first-child > div:first-child {
            opacity: 0;
            transform: translateY(20px);
            transition: opacity 800ms ease, transform 900ms cubic-bezier(0.16, 1, 0.3, 1);
        }

        .glass-card > div:first-child > div:nth-child(2) {
            transform: translateY(48px);
            transition: transform 900ms cubic-bezier(0.16, 1, 0.3, 1);
        }

        .glass-card > div:first-child > p {
            max-height: 0;
            margin-top: 0 !important;
            opacity: 0;
            overflow: hidden;
            pointer-events: none;
            transform: translateY(28px);
            font-family: 'Cormorant Garamond', Garamond, serif;
            font-weight: 500;
            letter-spacing: 0.01em;
            transition: max-height 900ms cubic-bezier(0.16, 1, 0.3, 1),
                        margin-top 900ms cubic-bezier(0.16, 1, 0.3, 1),
                        opacity 700ms ease,
                        transform 900ms cubic-bezier(0.16, 1, 0.3, 1);
        }

        .glass-card > div:last-child {
            transform: translateY(-72px);
            transition: transform 900ms cubic-bezier(0.16, 1, 0.3, 1),
                        border-color 900ms ease;
        }

        .glass-card.is-active > div:first-child > div:first-child {
            opacity: 1;
            transform: translateY(0);
        }

        .glass-card.is-active > div:first-child > div:nth-child(2) {
            transform: translateY(-36px);
        }

        .glass-card.is-active > div:first-child > p {
            max-height: 340px;
            margin-top: 1.25rem !important;
            opacity: 1;
            transform: translateY(0);
        }

        .glass-card.is-active > div:last-child {
            transform: translateY(24px);
        }

        /* ? JS ???? hover ??,?? CSS :hover ?????????? */
        #cards-grid.cards-hovering .glass-card {
            opacity: 1;
            filter: none;
        }

        #cards-grid.cards-hovering .glass-card:not(.is-active) .book-title-main,
        #cards-grid.cards-hovering .glass-card:not(.is-active) .book-title-main *,
        #cards-grid.cards-hovering .glass-card:not(.is-active) .year-label,
        #cards-grid.cards-hovering .glass-card:not(.is-active) .year-label *,
        #cards-grid.cards-hovering .glass-card:not(.is-active) .ui-type,
        #cards-grid.cards-hovering .glass-card:not(.is-active) .title-location {
            color: rgba(255, 255, 255, 0.1) !important;
            text-shadow: none !important;
        }

        /* ????????????,?????????/??? */
        #cards-grid.cards-hovering .glass-card.is-active {
            opacity: 1 !important;
            filter: brightness(1.1) !important;
            background: transparent !important;
            border-color: transparent !important;
            backdrop-filter: none !important;
            -webkit-backdrop-filter: none !important;
            box-shadow: none !important;
            transform: translateZ(0) !important;
        }

        /* ?????(???)????????? */
        .glass-card::before {
            content: '';
            position: absolute;
            top: 0; left: 0; right: 0; height: 1px;
            background: linear-gradient(90deg, transparent, rgba(255,255,255,0.15), transparent);
            opacity: 0;
            transition: opacity 0.5s ease;
        }

        .glass-card::after {
            content: "";
            position: absolute;
            inset: -2px;
            background-size: 200% 200%;
            opacity: 0;
            border-radius: inherit;
            transition: opacity 0.8s ease;
            z-index: -1;
            filter: blur(16px);
        }

        /* ????? block ??????? */
        /* Block 1: Squatter (???/???????) */
        #cards-grid .glass-card:nth-child(1)::after {
            background:
                radial-gradient(circle at 28% 35%, rgba(90, 66, 101, 0.95) 0%, transparent 54%),
                radial-gradient(circle at 72% 64%, rgba(77, 101, 66, 0.82) 0%, transparent 56%);
        }
        /* Block 2: I'm Here (???) */
        #cards-grid .glass-card:nth-child(2)::after {
            background: 
                radial-gradient(circle at 0% 0%, rgba(20, 60, 180, 0.6) 0%, transparent 50%),
                radial-gradient(circle at 100% 100%, rgba(5, 20, 100, 0.8) 0%, transparent 50%);
        }
        /* Block 3: Nineteen (??) */
        #cards-grid .glass-card:nth-child(3)::after {
            background: 
                radial-gradient(circle at 0% 0%, rgba(255, 215, 0, 0.6) 0%, transparent 50%),
                radial-gradient(circle at 100% 100%, rgba(255, 255, 50, 0.5) 0%, transparent 50%);
        }

        /* ???????????? JS ??,?? hover ???? */
        .glass-card.is-active::before { opacity: 1; }
        .glass-card.is-active::after {
            opacity: 0.5;
            animation: hover-light-drift 4.5s ease-in-out infinite alternate;
        }

        @keyframes hover-light-drift {
            0% { background-position: 0% 0%; transform: translate3d(-4%, -3%, 0) scale(0.92) rotate(-3deg); }
            25% { background-position: 100% 0%; transform: translate3d(4%, -2%, 0) scale(1.06) rotate(2deg); }
            50% { background-position: 100% 100%; transform: translate3d(3%, 4%, 0) scale(1.12) rotate(4deg); }
            75% { background-position: 0% 100%; transform: translate3d(-3%, 3%, 0) scale(1.08) rotate(-2deg); }
            100% { background-position: 0% 50%; transform: translate3d(2%, -1%, 0) scale(0.96) rotate(1deg); }
        }

        /* ???????????? */
        .contact-card {
            background: rgba(10, 10, 15, 0.4);
            backdrop-filter: blur(20px);
            -webkit-backdrop-filter: blur(20px);
            border: 1px solid rgba(255, 255, 255, 0.03);
            box-shadow: 0 0 20px rgba(0,0,0,0.5);
        }

        /* shader canvas ????????? */
        #glcanvas-container.cards-active {
            opacity: 0 !important;
        }
        #glcanvas-container {
            transition: opacity 1.5s ease-in-out;
        }

        .fade-in-up {
            opacity: 0; transform: translateY(30px);
        }

        #cards-grid.cards-ready .fade-in-up {
            animation: fadeInUp 1.5s cubic-bezier(0.16, 1, 0.3, 1) forwards;
        }

        @keyframes fadeInUp { 
            to { opacity: 1; transform: translateY(0); } 
        }

        .delay-1 { animation-delay: 0.2s; }
        .delay-2 { animation-delay: 0.4s; }
        .delay-3 { animation-delay: 0.6s; }
        .delay-4 { animation-delay: 0.8s; }

        .year-label {
            font-family: 'Share Tech Mono', monospace;
            letter-spacing: 0.15em;
            position: relative;
            min-width: 4ch;
            font-variant-numeric: tabular-nums;
            font-feature-settings: "tnum";
            color: rgba(255, 255, 255, 0.6);
            text-shadow: 0 0 8px rgba(255,255,255,0.18);
            transition: color 1.2s ease, text-shadow 1.2s ease, transform 1.2s cubic-bezier(0.16, 1, 0.3, 1), filter 1.2s ease;
        }

        .year-digits {
            display: inline-block;
            width: 4ch;
            text-align: center;
            transition: opacity 700ms ease, transform 900ms cubic-bezier(0.16, 1, 0.3, 1);
        }

        #cards-grid .glass-card.is-active:nth-child(1) .year-label {
            color: rgb(255, 255, 255) !important;
            text-shadow: 0 0 20px rgba(255,255,255,0.85), 0 0 44px rgba(255,255,255,0.55), 0 0 70px rgba(255,255,255,0.35) !important;
        }

        #cards-grid .glass-card.is-active:nth-child(2) .year-label {
            color: rgb(255, 255, 255) !important;
            text-shadow: 0 0 22px rgba(255,255,255,0.85), 0 0 52px rgba(255,255,255,0.55) !important;
        }

        #cards-grid .glass-card.is-active:nth-child(3) .year-label {
            color: rgb(255, 255, 255) !important;
            text-shadow: 0 0 24px rgba(255,255,255,0.85), 0 0 56px rgba(255,255,255,0.55) !important;
        }

        .deefunct-mark {
            font-family: 'Inter', sans-serif;
            font-style: italic;
            font-weight: 300;
            letter-spacing: 0.08em;
            transform: skewX(-7deg);
        }

        .location-label {
            font-family: 'Cormorant Garamond', Garamond, serif;
            font-size: 0.8rem;
            font-style: italic;
            font-weight: 400;
            letter-spacing: 0.14em;
        }

        .ui-type {
            font-family: 'Josefin Sans', sans-serif;
            font-weight: 500;
        }

        .literary-type {
            font-family: 'Cormorant Garamond', Garamond, serif;
            font-weight: 500;
        }

        .book-title-main {
            min-height: 58px;
            display: flex;
            align-items: center;
            justify-content: center;
            line-height: 1;
        }

        .title-location {
            font-family: 'Cormorant Garamond', Garamond, serif;
            font-size: 0.86rem;
            font-style: italic;
            font-weight: 400;
            letter-spacing: 0.12em;
            color: rgba(255, 255, 255, 0.58);
            opacity: 0;
            display: block;
            line-height: 1;
            margin-top: 16px;
            transform: translateY(8px);
            transition: opacity 700ms ease, transform 900ms cubic-bezier(0.16, 1, 0.3, 1);
        }

        .glass-card.is-active .title-location {
            opacity: 1;
            transform: translateY(0);
        }

        .nineteen-title {
            font-family: 'Josefin Sans', sans-serif;
            font-weight: 300;
            letter-spacing: 0.24em;
            text-transform: uppercase;
            transform: translateX(0.12em);
        }

        .heaven-type {
            font-family: 'Cormorant Garamond', serif;
            font-style: italic;
            font-weight: 500;
            letter-spacing: 0.22em;
        }

        .notify-toggle {
            position: relative;
            width: 44px;
            height: 24px;
            border-radius: 9999px;
            background: rgba(255,255,255,0.08);
            border: 1px solid rgba(255,255,255,0.12);
            transition: background 0.6s ease, border-color 0.6s ease;
        }

        .notify-toggle::after {
            content: '';
            position: absolute;
            top: 3px;
            left: 3px;
            width: 16px;
            height: 16px;
            border-radius: 9999px;
            background: rgba(255,255,255,0.7);
            transition: transform 0.6s cubic-bezier(0.16, 1, 0.3, 1), background 0.6s ease;
        }

        #notify-updates:checked + .notify-toggle {
            background: rgba(255,255,255,0.18);
            border-color: rgba(255,255,255,0.55);
        }

        #notify-updates:checked + .notify-toggle::after {
            transform: translateX(20px);
            background: rgb(255,255,255);
            box-shadow: 0 0 14px rgba(255,255,255,0.45);
        }

        #atmosphere-blur {
            position: fixed;
            inset: -24px;
            z-index: 2;
            pointer-events: none;
            --atmosphere-render-opacity: 0;
            --atmosphere-render-blur: 0px;
            --atmosphere-render-blur-soft: 0px;
            --atmosphere-render-blur-strong: 0px;
            --atmosphere-render-glow-opacity: 0;
            opacity: var(--atmosphere-render-opacity);
            backdrop-filter: blur(var(--atmosphere-render-blur));
            -webkit-backdrop-filter: blur(var(--atmosphere-render-blur));
            background: rgba(8, 8, 12, 0.035);
            transition: opacity 1.8s ease, backdrop-filter 1.8s ease, -webkit-backdrop-filter 1.8s ease, background 1.8s ease;
        }

        #atmosphere-blur::before {
            content: "";
            position: absolute;
            inset: -8%;
            opacity: 0;
            background:
                radial-gradient(circle at 28% 24%, rgba(255, 255, 255, 0.12), transparent 34%),
                radial-gradient(circle at 72% 68%, rgba(255, 220, 160, 0.1), transparent 38%),
                radial-gradient(circle at 52% 48%, rgba(140, 170, 255, 0.08), transparent 44%);
            filter: blur(26px);
            transform: translate3d(0, 0, 0) scale(1.02);
            transition: opacity 1.4s ease;
        }

        #atmosphere-blur.is-active {
            animation: atmosphere-blur-breathe 8.5s cubic-bezier(0.42, 0, 0.2, 1) infinite;
        }

        #atmosphere-blur.is-active::before {
            opacity: var(--atmosphere-render-glow-opacity);
            animation: atmosphere-active-glow-drift 11s cubic-bezier(0.42, 0, 0.2, 1) infinite;
        }

        @keyframes atmosphere-blur-breathe {
            0% {
                opacity: calc(var(--atmosphere-render-opacity) * 0.92);
                backdrop-filter: blur(var(--atmosphere-render-blur-soft));
                -webkit-backdrop-filter: blur(var(--atmosphere-render-blur-soft));
            }
            38% {
                opacity: calc(var(--atmosphere-render-opacity) * 1.08);
                backdrop-filter: blur(var(--atmosphere-render-blur-strong));
                -webkit-backdrop-filter: blur(var(--atmosphere-render-blur-strong));
            }
            64% {
                opacity: calc(var(--atmosphere-render-opacity) * 0.98);
                backdrop-filter: blur(var(--atmosphere-render-blur));
                -webkit-backdrop-filter: blur(var(--atmosphere-render-blur));
            }
            100% {
                opacity: calc(var(--atmosphere-render-opacity) * 0.9);
                backdrop-filter: blur(var(--atmosphere-render-blur-soft));
                -webkit-backdrop-filter: blur(var(--atmosphere-render-blur-soft));
            }
        }

        @keyframes atmosphere-active-glow-drift {
            0% {
                opacity: calc(var(--atmosphere-render-glow-opacity) * 0.78);
                transform: translate3d(-2%, -1%, 0) scale(1.02) rotate(-1deg);
            }
            16% {
                opacity: calc(var(--atmosphere-render-glow-opacity) * 1.18);
                transform: translate3d(1.5%, -2%, 0) scale(1.08) rotate(1deg);
            }
            31% {
                opacity: calc(var(--atmosphere-render-glow-opacity) * 0.92);
                transform: translate3d(3%, 1%, 0) scale(1.04) rotate(0deg);
            }
            47% {
                opacity: calc(var(--atmosphere-render-glow-opacity) * 1.35);
                transform: translate3d(0%, 2.5%, 0) scale(1.13) rotate(2deg);
            }
            66% {
                opacity: calc(var(--atmosphere-render-glow-opacity) * 1.02);
                transform: translate3d(-3%, 1%, 0) scale(1.07) rotate(-1deg);
            }
            83% {
                opacity: calc(var(--atmosphere-render-glow-opacity) * 1.24);
                transform: translate3d(-1%, -2.5%, 0) scale(1.1) rotate(1deg);
            }
            100% {
                opacity: calc(var(--atmosphere-render-glow-opacity) * 0.82);
                transform: translate3d(-2%, -1%, 0) scale(1.02) rotate(-1deg);
            }
        }

        .down-triangle {
            width: 0;
            height: 0;
            border-left: 5px solid transparent;
            border-right: 5px solid transparent;
            border-top: 7px solid rgba(255,255,255,0.62);
            filter: drop-shadow(0 0 8px rgba(255,255,255,0.18));
        }

        .up-triangle {
            width: 0;
            height: 0;
            border-left: 5px solid transparent;
            border-right: 5px solid transparent;
            border-bottom: 7px solid rgba(255,255,255,0.62);
            filter: drop-shadow(0 0 8px rgba(255,255,255,0.18));
        }

        .page-switcher.is-pinned {
            position: fixed !important;
            top: 32px !important;
            bottom: auto !important;
            z-index: 70;
        }

        .page-switcher .switcher-label,
        .page-switcher .switcher-arrow {
            position: absolute;
            transition: opacity 700ms ease, transform 800ms cubic-bezier(0.16, 1, 0.3, 1);
        }

        .page-switcher .switcher-down { transform: translateY(12px); opacity: 0; }
        .page-switcher .switcher-up { transform: translateY(-12px); opacity: 0; }

        .page-switcher:not(.is-contact-page):hover .switcher-label {
            opacity: 0;
            transform: translateY(-12px);
        }

        .page-switcher:not(.is-contact-page):hover .switcher-down {
            opacity: 1;
            transform: translateY(0);
        }

        .page-switcher.is-contact-page:hover .switcher-label {
            opacity: 0;
            transform: translateY(12px);
        }

        .page-switcher.is-contact-page:hover .switcher-up {
            opacity: 1;
            transform: translateY(0);
        }

        #intro-logo.nav-hidden {
            opacity: 1 !important;
            transform: translate(-50%, -50%) scale(0.35) translateY(-300px) !important;
            pointer-events: none;
            transition: transform 0s !important;
        }
        
        #intro-logo.nav-visible {
            transition: transform 0.5s cubic-bezier(0.16, 1, 0.3, 1) 0.3s !important;
        }