/* === CSS Custom Properties === */
:root {
    --void-black: #1C2128;
    --deep-slate: #2C3440;
    --sonar-blue: #3D5068;
    --dusty-teal: #6B8E9F;
    --faded-cyan: #9BBCCC;
    --muted-mauve: #8B7B8B;
    --stone-gray: #A09890;
    --aged-paper: #D4CCBE;
    --oxidized-umber: #4A3728;
    --node-teal: #4A6B7A;

    --ease-resonance: cubic-bezier(0.25, 0.46, 0.45, 0.94);
    --font-slab: 'Zilla Slab', Georgia, serif;
    --font-mono: 'Courier Prime', 'Courier New', monospace;
}

/* === Reset & Base === */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--void-black);
    color: var(--aged-paper);
    font-family: var(--font-slab);
    font-size: 18px;
    line-height: 1.75;
    overflow-x: hidden;
}

/* === Timeline Rail === */
.timeline-rail {
    position: fixed;
    left: 0;
    top: 0;
    width: 64px;
    height: 100vh;
    z-index: 100;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 32px;
    backdrop-filter: blur(1px);
    padding: 40px 0;
}

.rail-line {
    position: absolute;
    left: 50%;
    top: 40px;
    bottom: 40px;
    width: 1px;
    background: var(--sonar-blue);
    transform: translateX(-50%);
    transform-origin: top center;
    transform: scaleY(0) translateX(-50%);
    transition: transform 1.2s var(--ease-resonance);
}

.rail-line.drawn {
    transform: scaleY(1) translateX(-50%);
}

.rail-node {
    position: relative;
    z-index: 2;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: filter 0.6s var(--ease-resonance), transform 0.4s var(--ease-resonance);
    cursor: default;
}

.rail-node svg {
    opacity: 0.4;
    transition: opacity 0.6s var(--ease-resonance);
}

.rail-node.active svg {
    opacity: 1;
    filter: drop-shadow(0 0 6px rgba(155, 188, 204, 0.6));
}

.rail-node::after {
    content: attr(data-label);
    position: absolute;
    left: calc(100% + 8px);
    top: 50%;
    transform: translateY(-50%);
    font-family: var(--font-mono);
    font-size: 10px;
    letter-spacing: 0.12em;
    color: var(--dusty-teal);
    white-space: nowrap;
    opacity: 0;
    transition: opacity 0.3s var(--ease-resonance);
    pointer-events: none;
}

.rail-node.active::after {
    opacity: 0.7;
}

/* === Layers (Sections) === */
.layer {
    position: relative;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: 80px 100px 80px 120px;
    overflow: hidden;
}

/* === Ghost Numerals === */
.ghost-numeral {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-family: var(--font-slab);
    font-weight: 700;
    font-size: 120px;
    line-height: 1;
    color: var(--deep-slate);
    opacity: 0.15;
    pointer-events: none;
    user-select: none;
    z-index: 0;
    letter-spacing: 0;
}

/* === Gradient Mesh === */
.gradient-mesh {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at 20% 30%, var(--sonar-blue) 0%, transparent 60%),
        radial-gradient(ellipse at 80% 70%, var(--muted-mauve) 0%, transparent 55%),
        radial-gradient(ellipse at 50% 50%, var(--deep-slate) 0%, transparent 40%),
        var(--void-black);
    mix-blend-mode: normal;
    z-index: 0;
    pointer-events: none;
}

/* === Oscilloscope Container === */
.osc-container {
    position: absolute;
    bottom: 50%;
    left: 0;
    right: 0;
    width: 100%;
    pointer-events: none;
    z-index: 1;
    transform: translateY(50%);
}

.osc-layer3 {
    bottom: auto;
    top: 50%;
    transform: translateY(-50%);
}

.osc-wave {
    display: block;
    width: 100%;
}

/* === Layer 0: Hero === */
.layer-0 {
    background: var(--void-black);
    justify-content: center;
    align-items: center;
    text-align: center;
}

.hero-content {
    position: relative;
    z-index: 2;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 24px;
}

.wordmark-wrap {
    position: relative;
    display: inline-block;
}

.wordmark {
    font-family: var(--font-slab);
    font-weight: 700;
    font-size: 88px;
    line-height: 1;
    letter-spacing: -0.01em;
    color: var(--aged-paper);
    display: inline-block;
}

.wordmark-underline {
    display: block;
    margin: 8px auto 0;
    width: 100%;
    max-width: 600px;
}

.wordmark .char {
    display: inline-block;
    opacity: 0;
    transform: translateY(10px);
    transition: opacity 0.5s var(--ease-resonance), transform 0.5s var(--ease-resonance);
}

.wordmark .char.visible {
    opacity: 1;
    transform: translateY(0);
}

.hero-sub {
    font-family: var(--font-mono);
    font-size: 13px;
    letter-spacing: 0.12em;
    color: var(--dusty-teal);
    text-transform: uppercase;
    opacity: 0;
    transform: translateY(8px);
    transition: opacity 1s var(--ease-resonance) 1.5s, transform 1s var(--ease-resonance) 1.5s;
}

.hero-sub.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Resonance Sphere */
.resonance-sphere {
    position: absolute;
    width: 500px;
    height: 500px;
    border-radius: 50%;
    background:
        radial-gradient(ellipse at 35% 35%, var(--sonar-blue) 0%, transparent 50%),
        radial-gradient(ellipse at 65% 65%, var(--muted-mauve) 0%, transparent 45%),
        radial-gradient(ellipse at 50% 50%, var(--deep-slate) 0%, transparent 70%);
    opacity: 0.25;
    pointer-events: none;
    z-index: 1;
    animation: sphere-pulse 4s ease-in-out infinite;
}

@keyframes sphere-pulse {
    0%, 100% { transform: scale(1.0); }
    50% { transform: scale(1.03); }
}

/* === Section Header === */
.section-header {
    position: relative;
    z-index: 2;
    margin-bottom: 48px;
}

.timeline-marker {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 24px;
}

.section-id {
    font-family: var(--font-mono);
    font-size: 12px;
    letter-spacing: 0.12em;
    color: var(--dusty-teal);
    text-transform: uppercase;
}

.hairline {
    flex: 1;
    height: 1px;
    background: var(--sonar-blue);
    max-width: 300px;
}

.section-heading {
    font-family: var(--font-slab);
    font-weight: 700;
    font-size: 48px;
    line-height: 1.1;
    letter-spacing: -0.01em;
    color: var(--aged-paper);
    position: relative;
    display: inline-block;
}

/* Wave Underline SVG */
.wave-underline {
    display: block;
    margin-top: 6px;
    height: 20px;
}

.wave-underline-path {
    stroke-dasharray: 1000;
    stroke-dashoffset: 1000;
    transition: stroke-dashoffset 0.8s var(--ease-resonance);
}

.wave-underline-path.drawn {
    stroke-dashoffset: 0;
}

/* === Body Text === */
.body-text {
    font-family: var(--font-slab);
    font-weight: 400;
    font-size: 18px;
    line-height: 1.75;
    color: var(--stone-gray);
    max-width: 640px;
    margin-bottom: 24px;
}

.body-text:last-child {
    margin-bottom: 0;
}

.caption-mono {
    font-family: var(--font-mono);
    font-size: 12px;
    letter-spacing: 0.12em;
    color: var(--dusty-teal);
    text-transform: uppercase;
    line-height: 1.5;
    margin-top: 32px;
    opacity: 0.8;
}

/* === Scroll Reveal === */
.scroll-reveal {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 1s var(--ease-resonance), transform 1s var(--ease-resonance);
}

.scroll-reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* === Layer I: First Echo === */
.layer-1 {
    background: var(--void-black);
}

.layer-1-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 64px;
    align-items: center;
    position: relative;
    z-index: 2;
}

.chladni-wrap {
    display: flex;
    justify-content: center;
    align-items: center;
}

.chladni-fig {
    will-change: transform;
}

.chladni-path {
    stroke-dasharray: 2000;
    stroke-dashoffset: 2000;
    transition: stroke-dashoffset 1.2s ease-in-out;
}

.chladni-path.drawn {
    stroke-dashoffset: 0;
}

.typewriter-block {
    position: relative;
    z-index: 2;
}

.typewriter-text {
    font-family: var(--font-mono);
    font-size: 12px;
    letter-spacing: 0.12em;
    color: var(--dusty-teal);
    text-transform: uppercase;
    line-height: 1.8;
    margin-bottom: 32px;
    overflow: hidden;
}

.typewriter-text .typed-char {
    display: inline;
}

/* === Layer II: Interference === */
.layer-2 {
    background: var(--void-black);
    position: relative;
}

.layer-2-grid {
    display: grid;
    grid-template-columns: 3fr 2fr;
    gap: 64px;
    align-items: start;
    position: relative;
    z-index: 2;
    min-height: 80vh;
}

.layer-2-text {
    padding-top: 40px;
}

.layer-2-svg {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 500px;
    position: sticky;
    top: 100px;
}

.interference-svg {
    width: 100%;
    max-width: 380px;
    opacity: 0;
    transition: opacity 1.5s var(--ease-resonance);
}

.interference-svg.visible {
    opacity: 1;
}

.interference-bg-section {
    position: absolute;
    inset: 0;
    opacity: 0.08;
    pointer-events: none;
    z-index: 0;
}

/* === Layer III: Standing Wave === */
.layer-3 {
    background: var(--void-black);
    overflow: hidden;
}

.layer-3-mesh {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at 30% 40%, var(--sonar-blue) 0%, transparent 50%),
        radial-gradient(ellipse at 70% 60%, var(--muted-mauve) 0%, transparent 45%),
        var(--deep-slate);
    opacity: 0.6;
    z-index: 0;
    pointer-events: none;
    transition: background 2s var(--ease-resonance);
}

.layer-3.mid-scroll .layer-3-mesh {
    background:
        radial-gradient(ellipse at 30% 40%, var(--sonar-blue) 0%, transparent 50%),
        radial-gradient(ellipse at 70% 60%, var(--muted-mauve) 0%, transparent 45%),
        var(--muted-mauve);
}

.layer-content-inner {
    position: relative;
    z-index: 2;
    width: 100%;
}

.standing-wave-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 64px;
    align-items: center;
    margin-top: 40px;
}

.standing-wave-svg-wrap {
    display: flex;
    justify-content: center;
    align-items: center;
}

.chladni-large {
    width: 380px;
    height: 380px;
}

.standing-wave-text {
    display: flex;
    flex-direction: column;
    gap: 0;
}

/* === Layer IV: Node Map === */
.layer-4 {
    background: var(--void-black);
}

.node-map-layout {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 64px;
    align-items: start;
    margin-top: 40px;
}

.node-map-wrap {
    position: relative;
    opacity: 0;
    transition: opacity 1.5s var(--ease-resonance);
}

.node-map-wrap.visible {
    opacity: 1;
}

.node-map-svg {
    width: 100%;
    display: block;
}

.node-map-text {
    padding-top: 20px;
}

/* Node hover tooltip */
.node-tooltip {
    position: absolute;
    background: rgba(28, 33, 40, 0.9);
    border: 1px solid var(--sonar-blue);
    color: var(--dusty-teal);
    font-family: var(--font-mono);
    font-size: 11px;
    letter-spacing: 0.08em;
    padding: 4px 8px;
    pointer-events: none;
    z-index: 10;
    display: none;
    white-space: nowrap;
}

/* === Layer V: Decay === */
.layer-5 {
    background: var(--void-black);
    position: relative;
}

.layer-5-mesh {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at 40% 50%, rgba(61, 80, 104, 0.2) 0%, transparent 60%),
        radial-gradient(ellipse at 60% 50%, rgba(139, 123, 139, 0.1) 0%, transparent 50%),
        #0E1116;
    opacity: 1;
    z-index: 0;
    pointer-events: none;
}

.decay-content {
    justify-content: center;
}

.decay-blocks {
    position: relative;
    z-index: 2;
    max-width: 720px;
}

.decay-text-block {
    font-family: var(--font-slab);
    font-weight: 400;
    font-size: 20px;
    line-height: 1.75;
    color: var(--stone-gray);
    margin-bottom: 32px;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 1.2s var(--ease-resonance) calc(var(--stagger) * 0.3s), transform 1.2s var(--ease-resonance) calc(var(--stagger) * 0.3s);
}

.decay-text-block.visible {
    opacity: 1;
    transform: translateY(0);
}

.final-line-wrap {
    margin-top: 64px;
    position: relative;
    z-index: 2;
}

.final-line {
    font-family: var(--font-slab);
    font-weight: 700;
    font-size: 28px;
    line-height: 1.3;
    color: var(--aged-paper);
    letter-spacing: -0.01em;
    opacity: 0;
    transition: opacity 1s var(--ease-resonance) 0.9s;
}

.final-line.visible {
    opacity: 1;
}

.final-wave-underline {
    display: block;
    margin-top: 8px;
    max-width: 600px;
}

/* === Interference Background Pattern === */
.interference-bg {
    position: absolute;
    inset: 0;
    z-index: 1;
    pointer-events: none;
    overflow: hidden;
    opacity: 0.1;
}

/* === Scroll-reveal stagger utility === */
.scroll-reveal-stagger {
    opacity: 0;
    transform: translateY(20px);
}

/* === Responsive adjustments === */
@media (max-width: 1024px) {
    .layer {
        padding: 60px 60px 60px 80px;
    }

    .layer-1-content,
    .layer-2-grid,
    .standing-wave-grid,
    .node-map-layout {
        grid-template-columns: 1fr;
    }

    .wordmark {
        font-size: 56px;
    }

    .ghost-numeral {
        font-size: 80px;
    }

    .layer-2-svg {
        position: static;
        min-height: 300px;
    }

    .layer-2-grid {
        grid-template-columns: 1fr;
    }

    .interference-svg {
        max-width: 280px;
        margin: 0 auto;
        display: block;
    }

    .node-map-layout {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 640px) {
    .layer {
        padding: 40px 24px 40px 72px;
    }

    .wordmark {
        font-size: 40px;
    }

    .section-heading {
        font-size: 36px;
    }

    .timeline-rail {
        width: 48px;
    }
}