:root {
    color-scheme: light;
    --paper: #e8e2d7;
    --paper-light: #f5f1e9;
    --ink: #11110f;
    --muted: rgba(17, 17, 15, 0.58);
    --line: rgba(17, 17, 15, 0.2);
    --signal: #ef4b2f;
    --ease: cubic-bezier(0.22, 0.9, 0.3, 1);
}

* {
    box-sizing: border-box;
}

html,
body {
    min-width: 320px;
    min-height: 100%;
    margin: 0;
}

body {
    overflow: hidden;
    color: var(--ink);
    background: var(--paper);
    font-family: "Inter", "SF Pro Display", "Segoe UI", "Microsoft YaHei", "PingFang SC", sans-serif;
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
}

a {
    color: inherit;
    text-decoration: none;
}

::selection {
    color: var(--paper-light);
    background: var(--ink);
}

:focus-visible {
    outline: 2px solid var(--signal);
    outline-offset: 4px;
}

.skip-link {
    position: fixed;
    top: 12px;
    left: 16px;
    z-index: 100;
    padding: 10px 14px;
    color: #fff;
    background: var(--ink);
    transform: translateY(-180%);
    transition: transform 180ms ease;
}

.skip-link:focus {
    transform: translateY(0);
}

.topbar {
    position: fixed;
    top: max(18px, env(safe-area-inset-top));
    left: 50%;
    z-index: 80;
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    width: min(1500px, calc(100% - 48px));
    min-height: 48px;
    border-top: 1px solid var(--ink);
    border-bottom: 1px solid var(--ink);
    transform: translateX(-50%);
}

.back-link {
    display: inline-flex;
    width: fit-content;
    min-height: 46px;
    align-items: center;
    gap: 10px;
    font-size: 0.72rem;
    font-weight: 750;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    transition: color 180ms ease, transform 180ms var(--ease);
}

.back-link:hover,
.back-link:focus-visible {
    color: var(--signal);
    transform: translateX(-3px);
}

.topbar-title,
.counter {
    margin: 0;
    font-size: 0.66rem;
    font-weight: 750;
    letter-spacing: 0.16em;
    text-transform: uppercase;
}

.topbar-title {
    display: flex;
    align-items: center;
    gap: 9px;
}

.topbar-title i {
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: var(--signal);
    box-shadow: 0 0 0 5px rgba(239, 75, 47, 0.14);
}

.counter {
    justify-self: end;
    color: var(--muted);
}

.trail-stage {
    --pointer-x: 50vw;
    --pointer-y: 50vh;
    position: relative;
    height: 100svh;
    min-height: 620px;
    overflow: hidden;
    isolation: isolate;
    background:
        radial-gradient(circle 280px at var(--pointer-x) var(--pointer-y), rgba(255, 255, 255, 0.8), transparent 72%),
        linear-gradient(90deg, transparent calc(50% - 0.5px), rgba(17, 17, 15, 0.07) 50%, transparent calc(50% + 0.5px)),
        var(--paper);
}

.trail-stage::before {
    position: absolute;
    inset: 0;
    z-index: -1;
    content: "";
    opacity: 0.18;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 180 180' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='.5'/%3E%3C/svg%3E");
    mix-blend-mode: multiply;
    pointer-events: none;
}

.trail-field {
    position: absolute;
    inset: 0;
    z-index: 10;
    cursor: crosshair;
    touch-action: none;
}

.trail-card {
    --card-rotate: 0deg;
    position: absolute;
    top: 0;
    left: 0;
    width: clamp(128px, 17vw, 270px);
    aspect-ratio: 4 / 5;
    margin: 0;
    padding: clamp(7px, 0.7vw, 11px);
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.72);
    background: rgba(255, 255, 255, 0.86);
    box-shadow: 0 26px 70px rgba(27, 23, 17, 0.26);
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.72) rotate(var(--card-rotate));
    will-change: transform, opacity;
    pointer-events: none;
}

.trail-card img {
    display: block;
    width: 100%;
    height: calc(100% - 25px);
    object-fit: cover;
    filter: saturate(0.78) contrast(1.06);
    user-select: none;
}

.trail-card figcaption {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 25px;
    padding-top: 7px;
    color: #181714;
    font-family: "Courier New", monospace;
    font-size: clamp(0.48rem, 0.56vw, 0.64rem);
    font-weight: 700;
    letter-spacing: 0.12em;
}

.trail-card figcaption span {
    color: rgba(24, 23, 20, 0.48);
}

.trail-card-b {
    aspect-ratio: 1 / 1.18;
}

.trail-card-c {
    aspect-ratio: 1 / 1.08;
}

.trail-card-d {
    aspect-ratio: 4 / 5.35;
}

.pointer-orbit {
    position: absolute;
    top: 0;
    left: 0;
    z-index: 70;
    width: 56px;
    height: 56px;
    border: 1px solid var(--ink);
    border-radius: 50%;
    opacity: 0;
    transform: translate(-50%, -50%);
    transition: opacity 160ms ease;
    pointer-events: none;
}

.pointer-orbit::before,
.pointer-orbit::after {
    position: absolute;
    top: 50%;
    left: 50%;
    content: "";
    background: var(--ink);
    transform: translate(-50%, -50%);
}

.pointer-orbit::before {
    width: 72px;
    height: 1px;
}

.pointer-orbit::after {
    width: 1px;
    height: 72px;
}

.pointer-orbit i {
    position: absolute;
    inset: 8px;
    border: 1px solid rgba(17, 17, 15, 0.3);
    border-radius: 50%;
}

.pointer-orbit span {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--signal);
    transform: translate(-50%, -50%);
}

.trail-stage.is-tracking .pointer-orbit {
    opacity: 1;
}

.hero-copy {
    position: absolute;
    top: clamp(110px, 15vh, 168px);
    left: clamp(24px, 5vw, 82px);
    z-index: 4;
    width: min(650px, 47vw);
    pointer-events: none;
}

.eyebrow {
    display: flex;
    gap: 13px;
    align-items: center;
    margin: 0 0 clamp(16px, 2.4vh, 28px);
    font-size: clamp(0.56rem, 0.7vw, 0.72rem);
    font-weight: 750;
    letter-spacing: 0.16em;
    text-transform: uppercase;
}

.eyebrow span {
    padding: 5px 8px;
    color: var(--paper-light);
    background: var(--ink);
}

h1 {
    margin: 0;
    font-size: clamp(4.25rem, 10.2vw, 10.8rem);
    font-weight: 900;
    line-height: 0.7;
    letter-spacing: -0.09em;
    text-transform: uppercase;
}

h1 em {
    position: relative;
    left: clamp(22px, 5vw, 82px);
    color: transparent;
    font-style: normal;
    -webkit-text-stroke: 1.5px var(--ink);
}

.description {
    width: min(460px, 78%);
    margin: clamp(28px, 4.4vh, 54px) 0 0 clamp(22px, 5vw, 82px);
    color: var(--muted);
    font-size: clamp(0.8rem, 0.95vw, 1rem);
    line-height: 1.85;
}

.interaction-panel {
    position: absolute;
    top: 24%;
    right: clamp(24px, 5vw, 82px);
    z-index: 45;
    width: clamp(190px, 18vw, 260px);
    padding: 18px;
    border: 1px solid var(--ink);
    background: rgba(245, 241, 233, 0.86);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    pointer-events: none;
}

.panel-label {
    margin: 0;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--line);
    font-size: 0.58rem;
    font-weight: 800;
    letter-spacing: 0.18em;
}

.gesture-icon {
    position: relative;
    width: 90px;
    height: 48px;
    margin: 18px 0 12px;
}

.gesture-icon i {
    position: absolute;
    top: 22px;
    left: 0;
    width: 85px;
    border-top: 1px dashed var(--ink);
}

.gesture-icon span {
    position: absolute;
    top: 18px;
    width: 8px;
    height: 8px;
    border: 1px solid var(--ink);
    border-radius: 50%;
    background: var(--paper-light);
}

.gesture-icon span:nth-child(2) { left: 0; }
.gesture-icon span:nth-child(3) { left: 39px; background: var(--signal); border-color: var(--signal); }
.gesture-icon span:nth-child(4) { left: 78px; }

.prompt {
    margin: 0 0 18px;
    font-size: 0.76rem;
    font-weight: 650;
    line-height: 1.55;
}

.interaction-panel dl,
.interaction-panel dl div {
    margin: 0;
}

.interaction-panel dl {
    border-top: 1px solid var(--line);
}

.interaction-panel dl div {
    display: flex;
    justify-content: space-between;
    padding-top: 8px;
}

.interaction-panel dt,
.interaction-panel dd {
    margin: 0;
    color: var(--muted);
    font-family: "Courier New", monospace;
    font-size: 0.54rem;
    letter-spacing: 0.08em;
}

.interaction-panel dd {
    color: var(--ink);
    font-weight: 700;
}

.coordinate-readout {
    position: absolute;
    right: clamp(24px, 5vw, 82px);
    bottom: 128px;
    z-index: 45;
    display: flex;
    gap: 14px;
    font-family: "Courier New", monospace;
    font-size: 0.58rem;
    letter-spacing: 0.1em;
    pointer-events: none;
}

.coordinate-readout span {
    display: flex;
    gap: 5px;
}

.coordinate-readout b {
    min-width: 2.2em;
    font-weight: 400;
}

.bottom-bar {
    position: absolute;
    right: clamp(24px, 3vw, 48px);
    bottom: max(18px, env(safe-area-inset-bottom));
    left: clamp(24px, 3vw, 48px);
    z-index: 80;
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    min-height: 66px;
    border-top: 1px solid var(--ink);
}

.bottom-bar p {
    margin: 0;
    font-size: 0.58rem;
    font-weight: 750;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.bottom-bar > p:first-child {
    display: flex;
    align-items: center;
    gap: 9px;
}

.live-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--muted);
    transition: background 180ms ease, box-shadow 180ms ease;
}

.trail-stage.has-input .live-dot {
    background: var(--signal);
    box-shadow: 0 0 0 5px rgba(239, 75, 47, 0.13);
}

.sequence {
    color: var(--muted);
}

.next-link {
    display: inline-flex;
    justify-self: end;
    align-items: center;
    gap: 14px;
    min-height: 48px;
    padding-left: 18px;
    border-left: 1px solid var(--line);
    font-size: 0.73rem;
    font-weight: 750;
    letter-spacing: 0.04em;
    transition: color 180ms ease;
}

.next-link span {
    display: grid;
    gap: 2px;
}

.next-link small {
    color: var(--muted);
    font-size: 0.48rem;
    letter-spacing: 0.14em;
}

.next-link i {
    display: grid;
    width: 34px;
    height: 34px;
    place-items: center;
    border: 1px solid var(--ink);
    border-radius: 50%;
    font-style: normal;
    transition: color 180ms ease, background 180ms ease, transform 180ms var(--ease);
}

.next-link:hover,
.next-link:focus-visible {
    color: var(--signal);
}

.next-link:hover i,
.next-link:focus-visible i {
    color: #fff;
    background: var(--ink);
    transform: translate(2px, -2px);
}

.no-script {
    position: fixed;
    right: 16px;
    bottom: 16px;
    z-index: 100;
    margin: 0;
    padding: 10px 14px;
    color: #fff;
    background: var(--ink);
    font-size: 0.76rem;
}

@media (max-width: 760px) {
    .topbar {
        top: max(10px, env(safe-area-inset-top));
        width: calc(100% - 28px);
    }

    .topbar-title {
        display: none;
    }

    .trail-stage {
        min-height: 560px;
        background:
            radial-gradient(circle 180px at var(--pointer-x) var(--pointer-y), rgba(255, 255, 255, 0.82), transparent 72%),
            var(--paper);
    }

    .trail-card {
        width: clamp(105px, 38vw, 165px);
        padding: 6px;
    }

    .hero-copy {
        top: 18%;
        left: 18px;
        width: calc(100% - 36px);
    }

    .eyebrow {
        margin-bottom: 20px;
        font-size: 0.52rem;
    }

    h1 {
        font-size: clamp(4.2rem, 20.5vw, 7rem);
        line-height: 0.74;
    }

    h1 em {
        left: 8vw;
    }

    .description {
        width: min(86%, 390px);
        margin: 28px 0 0 8vw;
        font-size: 0.76rem;
        line-height: 1.7;
    }

    .interaction-panel {
        top: auto;
        right: auto;
        bottom: 94px;
        left: 18px;
        width: min(230px, calc(100% - 112px));
        padding: 12px;
    }

    .panel-label,
    .gesture-icon,
    .interaction-panel dl {
        display: none;
    }

    .prompt {
        margin: 0;
        font-size: 0.68rem;
    }

    .coordinate-readout,
    .sequence {
        display: none;
    }

    .bottom-bar {
        right: 18px;
        bottom: max(8px, env(safe-area-inset-bottom));
        left: 18px;
        grid-template-columns: 1fr auto;
        min-height: 72px;
    }

    .bottom-bar > p:first-child {
        max-width: 90px;
        line-height: 1.5;
    }

    .next-link {
        padding-left: 12px;
    }

    .pointer-orbit {
        width: 42px;
        height: 42px;
    }

    .pointer-orbit::before { width: 54px; }
    .pointer-orbit::after { height: 54px; }
}

@media (max-height: 650px) and (orientation: landscape) {
    .trail-stage {
        height: 100svh;
        min-height: 100svh;
    }

    .topbar {
        top: 8px;
    }

    .hero-copy {
        top: 84px;
        width: 52vw;
    }

    h1 {
        font-size: min(16vh, 7rem);
        line-height: 0.73;
    }

    .eyebrow {
        margin-bottom: 10px;
    }

    .description {
        display: none;
    }

    .interaction-panel {
        display: none;
    }

    .gesture-icon {
        height: 35px;
        margin: 8px 0 4px;
    }

    .gesture-icon i { top: 16px; }
    .gesture-icon span { top: 12px; }
    .interaction-panel dl { display: none; }
    .prompt { margin-bottom: 0; }
    .coordinate-readout { display: none; }

    .bottom-bar {
        min-height: 54px;
        bottom: 6px;
    }

    .trail-card {
        width: min(23vh, 170px);
    }
}

@media (prefers-reduced-motion: reduce) {
    .trail-stage {
        --pointer-x: 50vw;
        --pointer-y: 50vh;
    }

    .trail-field {
        cursor: default;
        touch-action: pan-y;
    }

    .trail-card {
        width: clamp(90px, 13vw, 180px);
        opacity: 0.92;
        transform: translate(-50%, -50%) rotate(var(--card-rotate));
    }

    .trail-card:nth-child(1) { top: 27%; left: 67%; --card-rotate: -8deg; }
    .trail-card:nth-child(2) { top: 49%; left: 73%; --card-rotate: 6deg; }
    .trail-card:nth-child(3) { top: 68%; left: 63%; --card-rotate: -3deg; }
    .trail-card:nth-child(4) { top: 41%; left: 86%; --card-rotate: 9deg; }
    .trail-card:nth-child(n + 5) { display: none; }

    .pointer-orbit {
        display: none;
    }

    .back-link,
    .next-link,
    .next-link i,
    .live-dot {
        transition: none;
    }
}

@media (prefers-reduced-motion: reduce) and (max-width: 760px) {
    .trail-card:nth-child(1) { top: 19%; left: 74%; }
    .trail-card:nth-child(2) { top: 44%; left: 79%; }
    .trail-card:nth-child(3) { top: 65%; left: 70%; }
    .trail-card:nth-child(4) { display: none; }
}