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

html { 
  scroll-behavior: smooth; 
}

:root {
  --bg:     rgb(243, 243, 243);
  --bg2:    rgb(243, 243, 243);
  --dark:   #141414;
  --mid:    #666;
  --rule:   #d6d4ce;
  --orange: #e84c0b;
  --white:  #f8f6f2;
}

body {
  font-family: 'IBM Plex Sans', sans-serif;
  background: var(--bg);
  color: var(--dark);
  overflow-x: hidden;
}

/* ── NAV ── */
nav {
  position: fixed; 
  top: 0; 
  left: 0; 
  right: 0; 
  height: 52px;
  display: flex; 
  align-items: center; 
  justify-content: space-between;
  padding: 0 24px;
  border-bottom: 1px solid var(--rule);
  z-index: 999;
  transition: background 0.3s;
}
nav.on-light  { background: rgba(243,243,243,0.96); }
nav.on-dark   { background: rgba(18,18,18,0.96); border-bottom-color: #2a2a2a; }
nav.on-white  { background: rgba(243,243,243,0.96); }
nav.on-light .nav-brand, nav.on-white .nav-brand { color: var(--dark); }
nav.on-dark  .nav-brand { color: #aaa; }

.nav-brand {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.65rem; 
  font-weight: 400;
  letter-spacing: 0.12em; 
  text-transform: uppercase;
}
.nav-links { 
  display: flex; 
  gap: 32px; 
}

.nav-links a {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.62rem; 
  font-weight: 400;
  letter-spacing: 0.14em; 
  text-transform: uppercase;
  text-decoration: none; 
  transition: color 0.2s;
}
a, nav.on-light .nav-links a, nav.on-white .nav-links a { color: var(--mid); }
a, nav.on-dark  .nav-links a { color: #555; }
a, .nav-links a:hover { color: var(--orange) !important; }

/* ══════════════════════════════════
   S1 — DID YOU KNOW
══════════════════════════════════ */
#s1 {
  min-height: 100vh;
  background: var(--bg);
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  text-align: center;
  padding: 80px 32px 80px;
  position: relative;
  overflow: hidden;
}

/* Background grid */
#s1::before {
  content: '';
  position: absolute; inset: 0;
  background-image:
    linear-gradient(var(--rule) 1px, transparent 1px),
    linear-gradient(90deg, var(--rule) 1px, transparent 1px);
  background-size: 48px 48px;
  opacity: 0.35;
  pointer-events: none;
  z-index: 0;
}

.home-title {
  font-family: 'IBM Plex Sans Condensed', sans-serif;
  line-height: 0.88;
  margin-bottom: 40px;
  position: relative; z-index: 1;
}
.home-title .t1 {
  display: block;
  font-size: clamp(2rem, 12vw, 1rem);
  font-weight: 700;
  color: var(--dark);
  letter-spacing: -0.02em;
  padding-bottom: 20px;
}
.home-title .t2 {
  display: block;
  font-size: clamp(3rem, 15vw, 3rem);
  font-weight: 700;
  -webkit-text-stroke: 0; 
  color: var(--orange); 
}
.home-title .t3 {
  font-size: clamp(2rem, 12vw, 1rem);
  font-weight: 700;
  color: var(--dark);
  letter-spacing: -0.02em;
  -webkit-text-stroke: 0px var(--dark);
} 

.home-title .t2 .dot { 
  -webkit-text-stroke: 0; 
  color: var(--orange); 
  font-size: 2rem;
}

.home-stat {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: clamp(0.9rem, 2.5vw, 1.15rem);
  font-weight: 300;
  color: #444;
  line-height: 1.4;
  max-width: 300px;
  position: relative; 
  z-index: 1;
}

.img {
  max-width: 200px;
  z-index: 10;
}

.soundwave {
  display: flex;
  align-items: center;
  gap: 4px;
  height: 120px;
  margin-top: 300px;
  position: absolute;
}

.bar {
  width: 6px;
  border-radius: 3px;
  background: #8a8a84;
  transform-origin: center;
  animation: wave 1.4s ease-in-out infinite;
}

@keyframes wave {
  0%, 100% { transform: scaleY(0.15); }
  50%       { transform: scaleY(1); }
}

.scroll-hint {
  position: absolute; 
  bottom: 38px; 
  left: 50%; 
  transform: translateX(-50%);
  display: flex; 
  flex-direction: column; 
  align-items: center; 
  gap: 8px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: .6rem; letter-spacing: 0.2em;
  text-transform: uppercase; color: #aaa;
}

.scroll-arrow { 
  font-size: 15px !important; 
  color: #999; 
  animation: bounce 2s ease-in-out infinite; 
}

@keyframes bounce { 
  0%,100% {
    transform:translateY(0)
  } 
  50%{
    transform:translateY(7px)
  } 
}

/* ══════════════════════════════════
   S2 — KEY COMPONENT
══════════════════════════════════ */
#s2 {
  min-height: 100vh;
  background: var(--dark);
  padding: 80px 24px 60px;
  display: flex; flex-direction: column;
  position: relative; overflow: hidden;
}

/* very subtle dot grid */
#s2::before {
  content: '';
  position: absolute; inset: 0;
  background-image: radial-gradient(circle, rgba(255,255,255,0.07) 1px, transparent 1px);
  background-size: 32px 32px;
  pointer-events: none;
}

.key-header {
  display: flex; justify-content: space-between;
  align-items: flex-start; margin-bottom: 18px;
  position: relative; z-index: 2;
}

.key-title {
  font-family: 'IBM Plex Sans Condensed', sans-serif;
  font-size: clamp(3rem, 10vw, 5.5rem);
  font-weight: 700; 
  color: var(--white);
  line-height: 0.95; 
  letter-spacing: -0.02em;
}
.key-title .num {
  color: var(--orange);
  font-style: normal;
}

.key-badge {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.58rem; 
  letter-spacing: 0.16em;
  text-transform: uppercase; 
  color: #555;
  text-align: right;
}
.blink-dot {
  display: inline-block; 
  width: 7px; 
  height: 7px;
  background: var(--orange); 
  border-radius: 50%;
  margin-right: 6px; 
  vertical-align: middle;
  animation: blink 1.4s ease-in-out infinite;
}

@keyframes blink { 0%,100%{opacity:1}50%{opacity:0.2} }

.key-card {
  flex: 1;
  min-height: min(580px, 90vw);
  background: #0e0e0e;
  border: 1px solid #222;
  border-radius: 8px;
  margin-top: 12px;
  position: relative;
  overflow: hidden;
  z-index: 2;
}

.headphone-model {
  position: relative;
  margin-left: 13%;
  margin-top: 10%;
  max-width: 250px;
}

.spec-row {
  position: absolute; 
  bottom: 0; 
  left: 0; 
  right: 0;
  border-top: 1px solid #222;
  display: flex;
}
.spec-cell {
  flex: 1; 
  padding: 14px 16px;
  border-right: 1px solid #222;
  opacity: 0; 
  transform: translateY(10px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}
.spec-cell:last-child { border-right: none; }
.spec-cell.show { opacity: 1; transform: translateY(0); }
.spec-cell:nth-child(2) { transition-delay: 0.12s; }
.spec-cell:nth-child(3) { transition-delay: 0.24s; }

.sc-num {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.6rem; color: var(--orange);
  margin-bottom: 5px; letter-spacing: 0.1em;
}
.sc-name {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.8rem; font-weight: 500; color: #ccc;
  margin-bottom: 3px;
}
.sc-desc {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.55rem; color: #848484; line-height: 1.5;
}

/* ══════════════════════════════════
   S3 — 5 STEPS
══════════════════════════════════ */
#s3 { background: var(--bg2); padding-bottom: 100px; }

.step {
  min-height: 100vh;
  display: flex; flex-direction: column;
  padding: 72px 28px 48px;
  opacity: 0; transform: translateY(60px);
  transition: opacity 1s cubic-bezier(0.22,1,0.36,1), transform 1s cubic-bezier(0.22,1,0.36,1);
  position: relative;
}
.step.show { opacity: 1; transform: translateY(0); }

/* staggered child animations once step is visible */
.step.show .circle-area  { animation: fadeUp 0.8s cubic-bezier(0.22,1,0.36,1) 0.1s both; }
.step.show .step-eyebrow { animation: fadeUp 0.7s cubic-bezier(0.22,1,0.36,1) 0.25s both; }
.step.show .step-title   { animation: fadeUp 0.7s cubic-bezier(0.22,1,0.36,1) 0.35s both; }
.step.show .title-rule   { animation: fadeUp 0.6s cubic-bezier(0.22,1,0.36,1) 0.4s both; }
.step.show .step-body    { animation: fadeUp 0.7s cubic-bezier(0.22,1,0.36,1) 0.45s both; }

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(24px); }
  to   { opacity: 1; transform: translateY(0); }
}

.step-index {
  font-family: 'IBM Plex Sans Condensed', sans-serif;
  font-size: clamp(5rem, 20vw, 8rem);
  font-weight: 700; line-height: 0.85;
  letter-spacing: -0.04em;
  color: var(--dark); opacity: 0.07;
  position: absolute; top: 56px; right: 24px;
  pointer-events: none;
}

.step-num-badge {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.65rem; font-weight: 700;
  color: var(--orange); letter-spacing: 0.05em;
}

.circle-area {
  position: relative;
  width: 260px; height: 260px;
  margin: 0 auto 44px; flex-shrink: 0;
}

.dring {
  position: absolute; 
  inset: -28px;
  border: 1px dashed #bbb; 
  border-radius: 50%;
}

.circ {
  width: 100%; height: 100%;
  border-radius: 50%;
  border: 2px solid var(--dark);
  background: var(--bg);
  display: flex; align-items: center; justify-content: center;
  position: relative;
  box-shadow:
    6px 8px 0 var(--dark),
    inset 0 0 0 8px rgba(0,0,0,0.04);
}

.badge {
  position: absolute; top: -10px; left: -10px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.65rem; font-weight: 700;
  color: #fff;
  background: var(--orange);
  width: 44px; height: 44px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  letter-spacing: 0.05em;
  border: 2px solid var(--bg2);
  z-index: 10;
}

.step-title {
  font-family: 'IBM Plex Sans Condensed', sans-serif;
  font-size: clamp(2.4rem, 8vw, 3.2rem);
  font-weight: 700; 
  color: var(--dark);
  line-height: 1; 
  margin-bottom: 18px;
  letter-spacing: -0.02em;
}

.title-rule {
  width: 230px; 
  height: 2px; 
  background: var(--orange); 
  margin-bottom: 20px;
}
.step-body {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.9rem; font-weight: 300; color: #555;
  line-height: 1.75; max-width: 420px;
}

.sdiv {
  display: flex; align-items: center; gap: 12px;
  padding: 0 28px;
}

.sdiv-line { 
  flex: 1; 
  height: 1px; 
  background: var(--rule); 
}

.sdiv-label {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.5rem; 
  color: var(--rule); 
  letter-spacing: 0.15em;
}

/* ══════════════════════════════════
   S4 — FINALE
══════════════════════════════════ */
#s4 {
  min-height: 100vh;
  background: var(--dark);
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  padding: 80px 32px;
  text-align: center;
  position: relative; overflow: hidden;
}

#s4::before {
  content: '';
  position: absolute; inset: 0;
  background-image: radial-gradient(circle, rgba(255,255,255,0.04) 1px, transparent 1px);
  background-size: 32px 32px;
  pointer-events: none;
}

.finale-bg {
  position: absolute;
  font-family: 'IBM Plex Sans Condensed', sans-serif;
  font-size: 20vw; 
  font-weight: 700; 
  line-height: 1;
  color: rgba(255,255,255,0.025);
  pointer-events: none; 
  user-select: none;
  letter-spacing: -0.04em; 
  bottom: 0vw;
  text-align: start;
  text-transform: uppercase;
}

.finale-rule { 
  width: 48px; 
  height: 2px; 
  background: var(--orange); 
  margin: 0 auto 32px; 
}

.finale-title {
  font-family: 'IBM Plex Sans Condensed', sans-serif;
  font-size: clamp(2.8rem, 10vw, 5.5rem);
  font-weight: 700; 
  color: var(--white);
  line-height: 0.95; 
  letter-spacing: -0.025em;
  margin-bottom: 8px; 
  position: relative; 
  z-index: 2;
  opacity: 0; 
  transform: translateY(24px);
  transition: opacity 0.8s ease, transform 0.8s ease;
}

.finale-title.show {
  opacity: 1; 
  transform: translateY(0); 
}

.finale-title .italic {
  font-style: italic;
  -webkit-text-stroke: 1.5px var(--white); color: transparent;
}

.finale-sub {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.6rem; letter-spacing: 0.24em;
  text-transform: uppercase; color: #444;
  margin-bottom: 56px; position: relative; z-index: 2;
  opacity: 0; transition: opacity 0.8s ease 0.2s;
}
.finale-sub.show { opacity: 1; }

.finale-btn {
  position: relative; z-index: 2;
  padding: 16px 44px;
  background: transparent;
  border: 1px solid #333; color: #aaa;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.62rem; font-weight: 400;
  letter-spacing: 0.18em; text-transform: uppercase;
  cursor: pointer;
  transition: all 0.2s;
  opacity: 0; transition: opacity 0.8s ease 0.4s, border-color 0.2s, color 0.2s, background 0.2s;
}
.finale-btn.show { opacity: 1; }
.finale-btn:hover { border-color: var(--orange); color: var(--orange); }

.fi {
  opacity: 0; transform: translateY(30px);
  transition: opacity 0.8s ease, transform 0.8s ease;
}
.fi.show { opacity: 1; transform: translateY(0); }
.fi.d1 { transition-delay: 0.2s; }
.fi.d2 { transition-delay: 1s; }