:root {
  --bg-base: #0c0c0e;
  --bg-elevated: #141416;
  --accent-copper: #c9895e;
  --accent-sage: #7a9e7e;
  --text-cream: #f0ebe3;
  --text-muted: #8a8580;
  --text-dim: #4a4540;
  --border-subtle: rgba(240, 235, 227, 0.06);
  --border-hover: rgba(201, 137, 94, 0.3);
  --ease-expo: cubic-bezier(0.16, 1, 0.3, 1);
  --font-serif: 'Crimson Pro', Georgia, serif;
  --font-mono: 'Space Mono', monospace;
  --font-body: 'Sora', sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  background: var(--bg-base);
  color: var(--text-cream);
  font-family: var(--font-body);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Noise grain overlay */
.noise-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 100;
  opacity: 0.03;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)'/%3E%3C/svg%3E");
}

#bg-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
}

/* Floating spiral decoration */
.spiral-deco {
  position: fixed;
  top: -100px;
  right: -100px;
  width: 600px;
  height: 600px;
  pointer-events: none;
  z-index: 0;
  opacity: 0.08;
}

.spiral-path {
  stroke: var(--accent-copper);
  stroke-width: 1;
  animation: spiralRotate 120s linear infinite;
  transform-origin: center;
}

@keyframes spiralRotate {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

.section {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  padding: 0 48px;
}

.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.9s var(--ease-expo), transform 0.9s var(--ease-expo);
}

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

/* ===== HERO ===== */
#hero {
  flex-direction: column;
  gap: 48px;
}

.hero-visual {
  display: flex;
  justify-content: center;
  align-items: center;
}

.logo-mark {
  width: 160px;
  height: 160px;
  position: relative;
}

.logo-svg {
  width: 100%;
  height: 100%;
  animation: logoPulse 4s ease-in-out infinite;
}

@keyframes logoPulse {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(1.03); opacity: 0.95; }
}

.hero-content {
  max-width: 900px;
  text-align: center;
}

.hero-pretitle {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 400;
  text-transform: uppercase;
  letter-spacing: 0.25em;
  color: var(--accent-copper);
  margin-bottom: 24px;
}

.hero-logo {
  font-family: var(--font-mono);
  font-size: clamp(48px, 9vw, 100px);
  font-weight: 700;
  color: var(--text-cream);
  margin-bottom: 20px;
  letter-spacing: -0.04em;
  line-height: 1.1;
}

.cursor {
  display: inline-block;
  animation: blink 1.1s step-end infinite;
  color: var(--accent-copper);
  font-weight: 400;
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0; }
}

.hero-subtitle {
  font-family: var(--font-body);
  font-size: clamp(16px, 2vw, 20px);
  font-weight: 300;
  color: var(--text-muted);
  max-width: 420px;
  margin: 0 auto;
  opacity: 0;
  transition: opacity 0.9s var(--ease-expo) 2.4s;
}

.hero-subtitle.is-visible {
  opacity: 1;
}

.scroll-indicator {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin-top: 64px;
  opacity: 0;
  transition: opacity 0.9s var(--ease-expo) 3.2s;
}

.scroll-indicator.is-visible {
  opacity: 1;
}

.scroll-line {
  display: block;
  width: 40px;
  height: 1px;
  background: var(--text-dim);
}

.scroll-text {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.2em;
}

/* ===== EULER SECTION ===== */
.euler-content {
  max-width: 1000px;
  width: 100%;
}

.euler-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 80px;
  align-items: center;
}

.number-visualization {
  position: relative;
}

.num-digits {
  display: flex;
  flex-wrap: wrap;
  gap: 2px;
  margin-bottom: 16px;
}

.digit {
  font-family: var(--font-mono);
  font-size: clamp(36px, 5vw, 64px);
  font-weight: 400;
  color: var(--text-dim);
  line-height: 1;
  transition: color 0.3s ease, transform 0.3s ease;
  cursor: default;
}

.digit:hover {
  color: var(--accent-copper);
  transform: translateY(-4px);
}

.digit.dot {
  color: var(--accent-copper);
  opacity: 0.6;
}

.num-label {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--text-dim);
}

.euler-text {
  position: relative;
}

.section-number {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-dim);
  font-weight: 400;
  margin-bottom: 12px;
  letter-spacing: 0.1em;
}

.section-title-small {
  font-family: var(--font-serif);
  font-size: clamp(32px, 4vw, 48px);
  font-weight: 700;
  color: var(--text-cream);
  margin-bottom: 24px;
  line-height: 1.15;
}

.euler-copy {
  font-family: var(--font-body);
  font-size: clamp(15px, 1.8vw, 17px);
  font-weight: 300;
  color: var(--text-muted);
  line-height: 1.75;
  margin-bottom: 32px;
}

.equation-morph {
  font-family: var(--font-mono);
  font-size: clamp(18px, 2.5vw, 24px);
  color: var(--accent-copper);
  opacity: 0;
  transform: translateX(-10px);
  transition: opacity 0.8s var(--ease-expo) 0.8s, transform 0.8s var(--ease-expo) 0.8s;
  letter-spacing: -0.02em;
}

.equation-morph.is-visible {
  opacity: 1;
  transform: translateX(0);
}

/* ===== RESEARCH / EXPERIMENTS ===== */
.experiments-content {
  max-width: 1100px;
  width: 100%;
}

.section-header {
  display: flex;
  align-items: baseline;
  gap: 20px;
  margin-bottom: 56px;
}

.section-title {
  font-family: var(--font-serif);
  font-size: clamp(36px, 5vw, 56px);
  font-weight: 700;
  color: var(--text-cream);
  line-height: 1.15;
  letter-spacing: -0.01em;
}

.research-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.research-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: 8px;
  overflow: hidden;
  transition: border-color 0.4s ease, transform 0.4s var(--ease-expo);
}

.research-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-4px);
}

.card-viz {
  background: rgba(0, 0, 0, 0.2);
  padding: 20px;
  border-bottom: 1px solid var(--border-subtle);
}

.mini-chart {
  width: 100%;
  height: 120px;
  display: block;
}

.card-content {
  padding: 24px;
}

.card-num {
  display: block;
  font-family: var(--font-serif);
  font-size: 18px;
  font-weight: 400;
  font-style: italic;
  color: var(--text-dim);
  margin-bottom: 8px;
  line-height: 1;
}

.card-content h3 {
  font-family: var(--font-serif);
  font-size: 24px;
  font-weight: 700;
  color: var(--text-cream);
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.card-content p {
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 300;
  color: var(--text-muted);
  line-height: 1.6;
}

.reveal[data-delay="1"].is-visible { transition-delay: 0.12s; }
.reveal[data-delay="2"].is-visible { transition-delay: 0.24s; }
.reveal[data-delay="3"].is-visible { transition-delay: 0.36s; }

/* ===== COMPOUNDING MATH ===== */
.math-content {
  max-width: 1100px;
  width: 100%;
}

.math-grid {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 80px;
  align-items: start;
}

.math-desc {
  font-family: var(--font-body);
  font-size: 17px;
  font-weight: 300;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 40px;
}

.slider-block {
  margin-bottom: 28px;
}

.slider-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.15em;
  margin-bottom: 14px;
}

.slider {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 2px;
  background: var(--border-subtle);
  border-radius: 1px;
  outline: none;
  margin-bottom: 16px;
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  background: var(--accent-copper);
  border-radius: 50%;
  cursor: pointer;
  border: 3px solid var(--bg-base);
  box-shadow: 0 0 0 1px var(--accent-copper);
}

.slider::-moz-range-thumb {
  width: 16px;
  height: 16px;
  background: var(--accent-copper);
  border-radius: 50%;
  cursor: pointer;
  border: 3px solid var(--bg-base);
  box-shadow: 0 0 0 1px var(--accent-copper);
}

.value-display {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 13px;
}

.years-val {
  color: var(--text-dim);
}

.money-val {
  color: var(--accent-copper);
  font-weight: 700;
}

.disclaimer {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--text-dim);
  margin-top: 20px;
  letter-spacing: 0.02em;
}

#curve-canvas {
  width: 100%;
  max-width: 500px;
  height: auto;
  display: block;
}

.viz-caption {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--border-subtle);
}

.viz-label {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.15em;
}

.viz-formula {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-muted);
}

.viz-formula sup {
  font-size: 8px;
}

/* ===== FOOTER ===== */
#footer {
  min-height: 60vh;
}

.footer-content {
  text-align: center;
  max-width: 600px;
  padding-top: 80px;
  padding-bottom: 60px;
}

.footer-visual {
  margin-bottom: 40px;
}

.footer-logo {
  width: 200px;
  height: 60px;
  margin: 0 auto;
  display: block;
}

.footer-rule {
  width: 0;
  height: 1px;
  background: var(--border-subtle);
  margin: 0 auto 32px;
  transition: width 1.2s var(--ease-expo);
}

.footer-rule.is-visible {
  width: 64px;
}

.footer-title {
  font-family: var(--font-serif);
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 700;
  color: var(--text-cream);
  margin-bottom: 12px;
  line-height: 1.2;
}

.footer-subtitle {
  font-family: var(--font-body);
  font-size: 16px;
  font-weight: 300;
  color: var(--text-muted);
  font-style: italic;
  margin-bottom: 40px;
}

.footer-copyright {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--text-dim);
  letter-spacing: 0.05em;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 1024px) {
  .section {
    padding: 0 32px;
  }
  .euler-grid {
    gap: 48px;
  }
  .math-grid {
    gap: 48px;
  }
}

@media (max-width: 768px) {
  .euler-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .math-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .math-viz {
    order: -1;
  }
  .research-grid {
    grid-template-columns: 1fr;
  }
  .logo-mark {
    width: 120px;
    height: 120px;
  }
}

@media (max-width: 640px) {
  .section {
    padding: 0 20px;
  }
  .hero-content {
    padding-top: 8vh;
  }
}

/* ===== REDUCED MOTION ===== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .cursor {
    animation: none;
    opacity: 0;
  }
  #bg-canvas, .spiral-deco {
    display: none;
  }
  body {
    background: var(--bg-base);
  }
}