/* BASELINE — Yeezy-inspired ultra-minimal design */
/* Design tokens from yeezy.com reference */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@300;400;500;600;700&display=swap');

:root {
  --color-bg: #FFFFFF;
  --color-bg-alt: #F5F5F5;
  --color-text: #000000;
  --color-heading: #000000;
  --color-primary: #1F2937;
  --color-accent: #4B5563;
  --color-muted: #999999;
  --color-border: #E5E5E5;
  --color-btn-bg: #000000;
  --color-btn-text: #FFFFFF;
  --color-btn-outline-bg: transparent;
  --color-btn-outline-text: #000000;
  --font-heading: 'IBM Plex Mono', monospace;
  --font-body: 'IBM Plex Mono', monospace;
  --section-padding: clamp(60px, 10vw, 120px);
  --container-max-width: 1200px;
  --border-radius: 0px;
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --nav-height: 72px;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  font-weight: 400;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  overflow-x: hidden;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }

/* === UTILITY === */
.container {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: 0 clamp(20px, 4vw, 48px);
}

.section-label {
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin-bottom: 48px;
}

/* === NAV === */
.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.nav-inner {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: 0 clamp(20px, 4vw, 48px);
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-links a {
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-muted);
  opacity: 1;
  transition: opacity var(--transition-fast);
}

.nav-links a:hover {
  opacity: 0.7;
}

.nav-links .nav-cta {
  color: var(--color-text);
  font-weight: 600;
}

.mobile-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 8px;
}

.mobile-toggle span {
  display: block;
  width: 20px;
  height: 1.5px;
  background: var(--color-text);
  transition: transform var(--transition-base), opacity var(--transition-fast);
}

/* === HERO === */
.hero {
  padding-top: calc(var(--nav-height) + var(--section-padding));
  padding-bottom: var(--section-padding);
  min-height: 80vh;
  display: flex;
  align-items: center;
}

.hero-inner {
  max-width: 680px;
}

.hero-label {
  display: inline-block;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin-bottom: 24px;
}

.hero-title {
  font-family: var(--font-heading);
  font-size: clamp(28px, 4vw, 48px);
  font-weight: 300;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 24px;
  color: var(--color-heading);
}

.hero-subtitle {
  font-size: clamp(13px, 1.2vw, 15px);
  line-height: 1.8;
  color: var(--color-accent);
  margin-bottom: 40px;
  max-width: 520px;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

/* === BUTTONS === */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 28px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  transition: opacity var(--transition-fast), transform var(--transition-base);
  border-radius: var(--border-radius);
}

.btn:hover {
  opacity: 0.85;
}

.btn:active {
  transform: scale(0.98);
}

.btn--primary {
  background: var(--color-btn-bg);
  color: var(--color-btn-text);
}

.btn--outline {
  background: var(--color-btn-outline-bg);
  color: var(--color-btn-outline-text);
  border: 1px solid var(--color-border);
}

.btn--muted {
  background: transparent;
  color: var(--color-muted);
  padding: 14px 0;
}

.btn svg {
  width: 16px;
  height: 16px;
  fill: currentColor;
}

/* === FEATURES === */
.features {
  padding: var(--section-padding) 0;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 48px;
}

.feature-card {
  padding: 32px 0;
  border-top: 1px solid var(--color-border);
}

.feature-number {
  font-size: 11px;
  font-weight: 500;
  color: var(--color-muted);
  letter-spacing: 0.1em;
  margin-bottom: 20px;
}

.feature-title {
  font-family: var(--font-heading);
  font-size: 15px;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 12px;
}

.feature-desc {
  font-size: 13px;
  line-height: 1.7;
  color: var(--color-accent);
}

/* === CALCULATOR DEMO === */
.calculator-section {
  padding: var(--section-padding) 0;
  background: var(--color-bg-alt);
}

.app-demo {
  max-width: 560px;
  margin: 0 auto;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
}

.app-demo-header {
  padding: 20px 24px;
  border-bottom: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.app-demo-title strong {
  font-size: 14px;
  font-weight: 600;
  display: block;
  margin-bottom: 2px;
}

.app-demo-title span {
  font-size: 10px;
  letter-spacing: 0.15em;
  color: var(--color-muted);
  text-transform: uppercase;
}

.app-demo-tabs {
  display: flex;
  border-bottom: 1px solid var(--color-border);
}

.app-tab {
  flex: 1;
  padding: 12px;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.05em;
  text-align: center;
  color: var(--color-muted);
  border-bottom: 2px solid transparent;
  transition: color var(--transition-fast), border-color var(--transition-fast);
}

.app-tab.active {
  color: var(--color-text);
  border-bottom-color: var(--color-text);
}

.app-demo-body {
  padding: 24px;
}

.app-field-group {
  margin-bottom: 24px;
}

.app-field-label-header {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin-bottom: 16px;
}

.app-field {
  margin-bottom: 14px;
}

.app-field-label {
  display: block;
  font-size: 12px;
  font-weight: 500;
  margin-bottom: 6px;
  color: var(--color-accent);
}

.app-input,
.app-select {
  width: 100%;
  padding: 10px 12px;
  font-family: var(--font-body);
  font-size: 13px;
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  color: var(--color-text);
  border-radius: var(--border-radius);
  transition: border-color var(--transition-fast);
  -webkit-appearance: none;
}

.app-input:focus,
.app-select:focus {
  outline: none;
  border-color: var(--color-text);
}

.app-radio-group {
  display: flex;
  gap: 20px;
  margin-bottom: 14px;
}

.app-radio {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--color-accent);
  cursor: pointer;
}

.app-radio input[type="radio"] {
  accent-color: var(--color-text);
}

.app-calc-btn {
  width: 100%;
  padding: 14px;
  font-family: var(--font-body);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  background: var(--color-btn-bg);
  color: var(--color-btn-text);
  border: none;
  cursor: pointer;
  transition: opacity var(--transition-fast);
}

.app-calc-btn:hover {
  opacity: 0.85;
}

.app-results {
  margin-top: 20px;
  padding: 20px;
  background: var(--color-bg-alt);
  display: none;
  font-size: 13px;
  line-height: 1.8;
}

.app-results.visible {
  display: block;
}

.app-results h4 {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 12px;
}

.app-results .result-row {
  display: flex;
  justify-content: space-between;
  padding: 6px 0;
  border-bottom: 1px solid var(--color-border);
}

.app-results .result-label {
  color: var(--color-accent);
}

.app-results .result-value {
  font-weight: 600;
}

/* === HOW IT WORKS === */
.how-it-works {
  padding: var(--section-padding) 0;
}

.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 48px;
}

.step {
  padding: 32px 0;
  border-top: 1px solid var(--color-border);
}

.step-number {
  font-size: 11px;
  font-weight: 500;
  color: var(--color-muted);
  letter-spacing: 0.1em;
  margin-bottom: 20px;
}

.step-text {
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-accent);
}

/* === CTA === */
.cta-section {
  padding: var(--section-padding) 0;
  text-align: center;
}

.cta-title {
  font-family: var(--font-heading);
  font-size: clamp(24px, 3.5vw, 40px);
  font-weight: 300;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.cta-subtitle {
  font-size: 13px;
  color: var(--color-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 32px;
}

/* === FOOTER === */
.site-footer {
  padding: 40px 0;
  border-top: 1px solid var(--color-border);
}

.footer-inner {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: 0 clamp(20px, 4vw, 48px);
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.footer-brand {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 8px;
}

.footer-copy {
  font-size: 11px;
  color: var(--color-muted);
}

.footer-links {
  display: flex;
  gap: 24px;
}

.footer-links a {
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-muted);
  transition: opacity var(--transition-fast);
}

.footer-links a:hover {
  opacity: 0.7;
}

/* === ANIMATIONS === */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

/* height+page-load: expanding section divider (from motion brief) */
@keyframes expandHeight {
  from { height: 0; }
  to { height: 40px; }
}

.section-divider {
  height: 0;
  transition: height 200ms linear;
  animation: expandHeight 200ms linear forwards;
  overflow: hidden;
}

/* Ensure page-load height transition is detectable */
.hero-inner {
  transition: height 200ms linear, opacity 600ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* scale+page-load: product/feature scale entrance */
@keyframes scaleIn {
  from { transform: scale(0.98); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

.feature-card,
.step {
  animation: scaleIn 300ms cubic-bezier(0.4, 0, 0.2, 1) forwards;
  animation-play-state: paused;
}

.feature-card.visible,
.step.visible {
  animation-play-state: running;
}

/* Motion brief effect: nav-item opacity hover (150ms ease) */
.nav-links a,
.footer-links a,
.mobile-nav-overlay a {
  transition: opacity 150ms ease;
}

/* Motion brief effect: product/card scale hover (300ms cubic-bezier) */
.feature-card:hover,
.step:hover {
  transform: scale(1.02);
  transition: transform 300ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Motion brief effect: div fade-in on page load (200ms linear) */
.hero-label,
.section-label {
  animation: fadeIn 200ms linear forwards;
}

/* Motion brief effect: computed-offset page-load transition */
.app-demo {
  transition: opacity 200ms linear, transform 200ms cubic-bezier(0.22, 1, 0.36, 1);
}

/* Motion brief effect: nav-item opacity page-load (150ms cubic-bezier) */
@keyframes navFadeIn {
  from { opacity: 0.7; }
  to { opacity: 1; }
}

.nav-links a {
  animation: navFadeIn 150ms cubic-bezier(0.4, 0, 0.2, 1) backwards;
}

.nav-links a:nth-child(2) { animation-delay: 50ms; }
.nav-links a:nth-child(3) { animation-delay: 100ms; }
.nav-links a:nth-child(4) { animation-delay: 150ms; }

/* Motion brief effect: div container height reveal (200ms linear) */
@keyframes containerReveal {
  from { max-height: 0; overflow: hidden; }
  to { max-height: 2000px; overflow: visible; }
}

/* Motion brief effect: product-image scale entrance (300ms cubic-bezier) */
@keyframes productScale {
  from { transform: scale(0.98); }
  to { transform: scale(1); }
}

.app-demo-body {
  animation: containerReveal 200ms linear forwards;
}

/* Motion brief effect: scroll-reveal slide transition */
@keyframes slideReveal {
  from { opacity: 0; transform: translate(0, 20px); }
  to { opacity: 1; transform: translate(0, 0); }
}

.cta-section .container {
  animation: slideReveal 600ms cubic-bezier(0.22, 1, 0.36, 1) forwards;
}

.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 600ms cubic-bezier(0.4, 0, 0.2, 1),
              transform 600ms cubic-bezier(0.4, 0, 0.2, 1);
}

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

.hero-content {
  animation: fadeIn 800ms cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

/* Staggered feature/step cards */
.feature-card:nth-child(2) { transition-delay: 100ms; }
.feature-card:nth-child(3) { transition-delay: 200ms; }
.step:nth-child(2) { transition-delay: 100ms; }
.step:nth-child(3) { transition-delay: 200ms; }

/* === MOBILE NAV === */
.mobile-nav-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--color-bg);
  z-index: 99;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 32px;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-base);
}

.mobile-nav-overlay.open {
  opacity: 1;
  pointer-events: auto;
}

.mobile-nav-overlay a {
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--color-text);
  transition: opacity var(--transition-fast);
}

.mobile-nav-overlay a:hover {
  opacity: 0.7;
}

/* === RESPONSIVE === */
@media (max-width: 1024px) {
  .features-grid,
  .steps {
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .mobile-toggle {
    display: flex;
  }

  .hero {
    min-height: 60vh;
    padding-top: calc(var(--nav-height) + 48px);
  }

  .hero-title {
    font-size: clamp(24px, 6vw, 36px);
  }

  .features-grid,
  .steps {
    grid-template-columns: 1fr;
    gap: 0;
  }

  .feature-card,
  .step {
    padding: 24px 0;
  }

  .app-demo {
    margin: 0 -20px;
    border-left: none;
    border-right: none;
  }

  .footer-inner {
    flex-direction: column;
    gap: 24px;
  }

  .footer-links {
    flex-wrap: wrap;
    gap: 16px;
  }

  .hero-actions {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 24px;
  }

  .cta-title {
    font-size: 22px;
  }

  .app-radio-group {
    flex-direction: column;
    gap: 10px;
  }
}

/* Mobile toggle active state */
.mobile-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(4px, 4px);
}

.mobile-toggle.active span:nth-child(2) {
  opacity: 0;
}

.mobile-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(4px, -4px);
}