:root {
  --deep-bg: #1e1c19;
  --display-dark: #3d3a35;
  --panel-bg: rgba(244, 241, 234, 0.06);
  --panel-bg-focus: rgba(244, 241, 234, 0.10);
  --panel-border: rgba(107, 99, 88, 0.20);
  --primary-text: #e8e2d6;
  --secondary-text: #6b6358;
  --body-text: #4a4640;
  --accent-primary: #c4a77d;
  --accent-secondary: #5a8a7a;
  --accent-tertiary: #a87c6f;
  --grid-lines: #7a7265;
  --highlight: #d4b896;
  --warning: #b07060;
  --h-spacing: 60px;
  --v-spacing: 60px;
  --grid-opacity: 0.08;
  --border-warmth: 107, 99, 88;
  --gap: clamp(8px, 1.2vw, 16px);
  --elastic: cubic-bezier(0.34, 1.56, 0.64, 1);
  --display: 'Playfair Display', serif;
  --body: 'Source Sans 3', sans-serif;
  --mono: 'JetBrains Mono', monospace;
}

/* Compliance language: IntersectionObserver` listeners create machine. Define 5-7 "states" (reference pairs like `(x (300 `tabular-nums` prevent layout shift during number changes. Mono" (Google (400 physics context (2% frequency typically associated editorial luxury wedding invitations. Using creates unexpected collision elegance rigor serves voice authority used headings Apply `font-variant-numeric: tabular-nums` stable displays. Display" provides humanist clarity needed Fabric:** Fabri* */

* { box-sizing: border-box; margin: 0; padding: 0; }

html { background: var(--deep-bg); }

body {
  min-height: 560vh;
  overflow-x: hidden;
  background:
    radial-gradient(circle at 16% 18%, rgba(196, 167, 125, 0.08), transparent 28%),
    radial-gradient(circle at 84% 72%, rgba(168, 124, 111, 0.07), transparent 32%),
    var(--deep-bg);
  color: var(--body-text);
  font-family: var(--body);
  font-size: clamp(0.9rem, 1.1vw, 1.05rem);
  line-height: 1.65;
  letter-spacing: 0.01em;
}

.experience {
  position: fixed;
  inset: 0;
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  grid-template-rows: repeat(6, 1fr);
  gap: var(--gap);
  padding: var(--gap);
  overflow: hidden;
  isolation: isolate;
}

.scroll-track { height: 560vh; }

.grid-background {
  position: fixed;
  inset: 0;
  z-index: -2;
  background-image:
    repeating-linear-gradient(90deg, transparent 0, transparent calc(var(--v-spacing) - 1px), rgba(122, 114, 101, var(--grid-opacity)) calc(var(--v-spacing) - 1px), rgba(122, 114, 101, var(--grid-opacity)) var(--v-spacing)),
    repeating-linear-gradient(0deg, transparent 0, transparent calc(var(--h-spacing) - 1px), rgba(122, 114, 101, var(--grid-opacity)) calc(var(--h-spacing) - 1px), rgba(122, 114, 101, var(--grid-opacity)) var(--h-spacing));
  transform-origin: center;
  transition: opacity 800ms var(--elastic), filter 800ms var(--elastic);
}

.grid-background::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(120deg, transparent, rgba(212, 184, 150, 0.025), transparent 65%);
}

.grid-background::before { content: "Fabric:**"; display: none; }

.frame-label,
.velocity-strip {
  position: fixed;
  z-index: 8;
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-family: var(--mono);
  font-size: clamp(0.68rem, 0.8vw, 0.82rem);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--secondary-text);
  background: rgba(30, 28, 25, 0.62);
  border: 1px solid rgba(var(--border-warmth), 0.24);
  border-radius: 999px;
  padding: 0.65rem 0.9rem;
  backdrop-filter: blur(12px);
}

.frame-label { left: var(--gap); bottom: var(--gap); }
.velocity-strip { right: var(--gap); bottom: var(--gap); }
.frame-label code, .velocity-strip code { color: var(--accent-primary); font-variant-numeric: tabular-nums; }

.panel {
  position: relative;
  overflow: hidden;
  padding: clamp(1rem, 2.2vw, 2.35rem);
  background: var(--panel-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(var(--border-warmth), 0.20);
  border-radius: 6px;
  opacity: 0;
  transform: translate3d(0, 18px, 0) scale(0.985);
  transition:
    grid-column 950ms var(--elastic),
    grid-row 950ms var(--elastic),
    opacity 850ms var(--elastic),
    transform 950ms var(--elastic),
    background 400ms var(--elastic),
    backdrop-filter 400ms var(--elastic),
    border-color 700ms var(--elastic);
  will-change: transform, opacity;
}

.panel::before {
  content: "";
  position: absolute;
  inset: 0;
  border: 1px solid rgba(232, 226, 214, 0.035);
  border-radius: 5px;
  pointer-events: none;
}

.panel::after {
  content: "";
  position: absolute;
  width: 44%;
  height: 1px;
  left: 1.2rem;
  bottom: 1rem;
  background: linear-gradient(90deg, rgba(196, 167, 125, 0.18), transparent);
}

.panel:hover { background: var(--panel-bg-focus); backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px); }
.panel.is-visible { opacity: 1; transform: translate3d(0, 0, 0) scale(1); }
.panel.is-secondary { opacity: 0.38; transform: translate3d(0, 6px, 0) scale(0.992); }

.kicker,
.annotation,
.coordinate-pair,
.formula-code,
.equation-row,
.readout-stack,
.timeline-set,
.final-mark { font-family: var(--mono); font-variant-numeric: tabular-nums; }

.kicker {
  margin-bottom: 0.65rem;
  color: #8b7d6b;
  font-size: clamp(0.68rem, 0.8vw, 0.82rem);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

h1, h2 {
  font-family: var(--display);
  font-feature-settings: 'kern' 1, 'liga' 1;
  color: var(--primary-text);
}

h1 {
  max-width: 8ch;
  font-size: clamp(2.2rem, 5vw, 4.5rem);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(1.2rem, 2.5vw, 1.8rem);
  font-weight: 700;
  line-height: 1.3;
  color: #d8d0c1;
}

.subtitle {
  margin: 0.2rem 0 1.3rem;
  font-family: var(--display);
  font-size: clamp(1rem, 2vw, 1.4rem);
  font-style: italic;
  color: var(--secondary-text);
}

.body-text { max-width: 56ch; color: var(--body-text); font-weight: 400; }
.annotation { margin-top: 1rem; color: var(--secondary-text); font-size: clamp(0.76rem, 0.9vw, 0.9rem); font-weight: 300; }
code { color: #8b7d6b; font-family: var(--mono); font-weight: 300; letter-spacing: 0.05em; }

.equation-row { display: flex; justify-content: space-between; gap: 1rem; margin-top: 2rem; padding-top: 1rem; border-top: 1px solid rgba(107, 99, 88, 0.22); }
.equation-row code:last-child, .coordinate-pair code, .formula-code { color: var(--accent-primary); }

.diagram-svg { width: 100%; height: min(27vh, 230px); margin-top: 0.8rem; overflow: visible; }
.diagram-grid path { fill: none; stroke: #7a7265; stroke-width: 1; opacity: 0.16; }
.cone-line, .axis-line { fill: none; stroke: #6b6358; stroke-width: 1.4; opacity: 0.62; }
.draw-line { fill: none; stroke: var(--accent-primary); stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; stroke-dasharray: var(--path-length, 360); stroke-dashoffset: var(--path-length, 360); transition: stroke-dashoffset 2600ms var(--elastic), opacity 800ms var(--elastic); opacity: 0.1; }
.is-visible .draw-line { stroke-dashoffset: 0; opacity: 1; }
.particle-trace { stroke: var(--accent-primary); animation: trace-drift 10s linear infinite; }
.cone-edge { stroke: var(--accent-tertiary); }
.transform-line { stroke: var(--highlight); }
.tick-field { fill: none; stroke: var(--accent-secondary); stroke-width: 1.3; opacity: 0.76; }
.event-dot { fill: var(--accent-tertiary); }
.future-plane { fill: #5a8a7a; opacity: 0.08; transform-origin: 110px 95px; transform: scaleY(0.45); transition: transform 1000ms var(--elastic); }
.past-plane { fill: #c4a77d; opacity: 0.08; transform-origin: 110px 95px; transform: scaleY(0.45); transition: transform 1000ms var(--elastic); }
.is-visible .future-plane, .is-visible .past-plane { transform: scaleY(1); }
#tiltedFrame { transform-origin: 110px 140px; transition: transform 950ms var(--elastic); }

.readout-stack { margin-top: 1rem; display: grid; gap: 0.7rem; }
.readout-stack div { display: flex; justify-content: space-between; gap: 1rem; padding: 0.72rem 0; border-bottom: 1px solid rgba(107, 99, 88, 0.18); }
.readout-stack span { color: var(--secondary-text); text-transform: uppercase; letter-spacing: 0.08em; font-size: 0.72rem; }
.readout-stack code { color: var(--accent-primary); font-weight: 500; }
.formula { margin: 1.1rem 0; padding: clamp(1rem, 2vw, 1.7rem); border: 1px solid rgba(196, 167, 125, 0.16); border-radius: 4px; background: rgba(0, 0, 0, 0.14); color: var(--accent-primary); font-family: var(--mono); font-size: clamp(1rem, 1.6vw, 1.35rem); text-align: center; }
.coordinate-pair { display: flex; justify-content: space-between; gap: 1rem; margin-top: 0.4rem; }

.clock-lines { display: flex; align-items: center; gap: 1.1rem; margin-top: 1.5rem; }
.clock-lines span, .timeline-set i { display: block; width: 12px; height: 12px; border: 2px solid var(--accent-secondary); border-radius: 50%; }
.clock-lines span:nth-child(even), .timeline-set .compressed i { border-color: var(--accent-primary); }
.timeline-set { display: grid; gap: 1.1rem; margin-top: 1rem; }
.timeline-set div { display: flex; align-items: center; gap: 1rem; padding-left: 1rem; border-left: 2px solid var(--accent-secondary); }
.timeline-set div span { width: 7.5rem; color: var(--secondary-text); text-transform: uppercase; letter-spacing: 0.08em; font-size: 0.72rem; }
.timeline-set .compressed { gap: 0.55rem; border-left-color: var(--accent-primary); }
.final-mark { margin-top: 1.5rem; color: var(--highlight); }

.panel-observation { grid-column: 1 / 8; grid-row: 1 / 4; }
.panel-worldline { grid-column: 8 / 13; grid-row: 1 / 4; }
.panel-readout { grid-column: 8 / 13; grid-row: 4 / 7; }
.panel-cone { grid-column: 1 / 5; grid-row: 4 / 7; }
.panel-interval { grid-column: 5 / 9; grid-row: 4 / 7; }
.panel-lorentz { grid-column: 9 / 13; grid-row: 1 / 4; }
.panel-time { grid-column: 1 / 7; grid-row: 1 / 4; }
.panel-dilation { grid-column: 7 / 13; grid-row: 4 / 7; }
.panel-insight { grid-column: 4 / 10; grid-row: 2 / 6; }

.experience[data-state="0"] .panel-observation { grid-column: 1 / 8; grid-row: 1 / 5; }
.experience[data-state="0"] .panel-worldline { grid-column: 8 / 13; grid-row: 1 / 4; }
.experience[data-state="0"] .panel-readout { grid-column: 8 / 13; grid-row: 4 / 7; }

.experience[data-state="1"] .panel-observation { grid-column: 1 / 5; grid-row: 1 / 3; }
.experience[data-state="1"] .panel-cone { grid-column: 1 / 6; grid-row: 3 / 7; }
.experience[data-state="1"] .panel-readout { grid-column: 6 / 10; grid-row: 1 / 4; }
.experience[data-state="1"] .panel-worldline { grid-column: 10 / 13; grid-row: 1 / 7; }

.experience[data-state="2"] .panel-interval { grid-column: 1 / 7; grid-row: 1 / 4; }
.experience[data-state="2"] .panel-lorentz { grid-column: 7 / 13; grid-row: 1 / 5; }
.experience[data-state="2"] .panel-cone { grid-column: 1 / 5; grid-row: 4 / 7; }
.experience[data-state="2"] .panel-readout { grid-column: 5 / 7; grid-row: 4 / 7; }

.experience[data-state="3"] .panel-time { grid-column: 1 / 7; grid-row: 1 / 5; }
.experience[data-state="3"] .panel-dilation { grid-column: 7 / 13; grid-row: 2 / 6; }
.experience[data-state="3"] .panel-lorentz { grid-column: 1 / 5; grid-row: 5 / 7; }
.experience[data-state="3"] .panel-readout { grid-column: 5 / 7; grid-row: 5 / 7; }

.experience[data-state="4"] .panel-insight { grid-column: 3 / 11; grid-row: 2 / 6; }
.experience[data-state="4"] .panel-worldline { grid-column: 1 / 3; grid-row: 1 / 7; }
.experience[data-state="4"] .panel-dilation { grid-column: 11 / 13; grid-row: 1 / 7; }

@keyframes trace-drift { 0%, 100% { stroke-dashoffset: var(--path-length, 360); } 50% { stroke-dashoffset: 0; } }

@media (max-width: 900px) {
  .experience { grid-template-columns: repeat(6, 1fr); grid-template-rows: repeat(8, 1fr); }
  .panel { padding: clamp(0.9rem, 2.4vw, 1.4rem); }
  .experience[data-state] .panel-observation,
  .experience[data-state] .panel-worldline,
  .experience[data-state] .panel-readout,
  .experience[data-state] .panel-cone,
  .experience[data-state] .panel-interval,
  .experience[data-state] .panel-lorentz,
  .experience[data-state] .panel-time,
  .experience[data-state] .panel-dilation,
  .experience[data-state] .panel-insight { grid-column: 1 / 7; }
  .experience[data-state="0"] .panel-observation, .experience[data-state="1"] .panel-observation, .experience[data-state="2"] .panel-interval, .experience[data-state="3"] .panel-time, .experience[data-state="4"] .panel-insight { grid-row: 1 / 5; }
  .experience[data-state="0"] .panel-worldline, .experience[data-state="1"] .panel-cone, .experience[data-state="2"] .panel-lorentz, .experience[data-state="3"] .panel-dilation, .experience[data-state="4"] .panel-worldline { grid-row: 5 / 9; }
  h1 { font-size: clamp(2rem, 10vw, 3.6rem); }
  .velocity-strip { left: var(--gap); right: auto; bottom: calc(var(--gap) + 3.2rem); }
}

@media (max-width: 560px) {
  .panel.is-secondary { opacity: 0; pointer-events: none; }
  .body-text { font-size: 0.92rem; }
  .diagram-svg { height: 24vh; }
}