/* ============================================================
   ThenWatt — single-page launch site
   Self-contained: system fonts, no external assets.
   ============================================================ */

:root {
  --ink: #16181d;
  --ink-soft: #4b5160;
  --paper: #ffffff;
  --tint: #f5f6f8;
  --dark: #101319;
  --dark-soft: #aab2c0;
  --accent: #f5a623;        /* warm watt-amber */
  --accent-deep: #e08700;
  --glow: #ffd87a;
  --radius: 16px;
  --maxw: 1100px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue",
          Arial, sans-serif;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img, svg { max-width: 100%; display: block; }

/* ---------- typography ---------- */

h1 {
  font-size: clamp(2.6rem, 6.5vw, 4.6rem);
  line-height: 1.05;
  letter-spacing: -0.03em;
  font-weight: 800;
}

h2 {
  font-size: clamp(1.9rem, 4vw, 3rem);
  line-height: 1.12;
  letter-spacing: -0.02em;
  font-weight: 750;
  margin-bottom: 1rem;
}

h3 { font-size: 1.25rem; font-weight: 700; margin-bottom: 0.5rem; }

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent-deep);
  margin-bottom: 1rem;
}

.lead {
  font-size: 1.18rem;
  color: var(--ink-soft);
  max-width: 46em;
}

.accent { color: var(--accent); }

/* ---------- layout ---------- */

.container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }
.narrow    { max-width: 820px; }
.center    { text-align: center; }

.section { padding: 110px 0; }

.section-tint { background: var(--tint); }

.section-dark {
  background: var(--dark);
  color: #f2f4f8;
}
.section-dark .lead { color: var(--dark-soft); }
.section-dark h2 { color: #fff; }

/* ---------- nav ---------- */

.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.82);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.nav-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  gap: 28px;
}

.logo {
  font-size: 1.3rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  text-decoration: none;
  color: var(--ink);
}
.logo span { color: var(--accent-deep); }

.nav-links {
  display: flex;
  gap: 22px;
  margin-left: auto;
}

.nav-links a {
  text-decoration: none;
  color: var(--ink-soft);
  font-size: 0.95rem;
  font-weight: 600;
}
.nav-links a:hover { color: var(--ink); }

/* ---------- buttons ---------- */

.btn {
  display: inline-block;
  background: var(--accent);
  color: #1d1503;
  font-weight: 700;
  text-decoration: none;
  border: none;
  cursor: pointer;
  padding: 14px 28px;
  border-radius: 999px;
  font-size: 1rem;
  transition: transform 0.15s ease, background 0.15s ease;
}
.btn:hover { background: var(--accent-deep); transform: translateY(-1px); }

.btn-small { padding: 9px 18px; font-size: 0.9rem; }

.btn-ghost {
  background: transparent;
  color: var(--ink);
  box-shadow: inset 0 0 0 2px rgba(0, 0, 0, 0.15);
}
.btn-ghost:hover { background: rgba(0, 0, 0, 0.05); transform: none; }

/* ---------- hero ---------- */

.hero {
  background:
    radial-gradient(1200px 500px at 70% -10%, #fff3d8 0%, transparent 60%),
    linear-gradient(180deg, #fffdf8 0%, #ffffff 100%);
  padding: 120px 0 40px;
  overflow: hidden;
}

.hero-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
  text-align: center;
}

.hero-sub {
  font-size: 1.25rem;
  color: var(--ink-soft);
  max-width: 40em;
  margin: 1.4rem auto 2.2rem;
}

.hero-cta { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }

.hero-art { margin: 56px auto 0; max-width: 860px; }

/* hero SVG styling */
.art { width: 100%; height: auto; }

.bulb-glass {
  fill: var(--glow);
  stroke: var(--accent-deep);
  stroke-width: 2.5;
}
.bulb-base { fill: #9aa1ad; }

.switch-plate {
  fill: #fff;
  stroke: #c8cdd6;
  stroke-width: 2.5;
}
.switch-rocker { fill: var(--glow); stroke: var(--accent-deep); stroke-width: 2; }

.plug-body {
  fill: #fff;
  stroke: #c8cdd6;
  stroke-width: 2.5;
}
.plug-slot { fill: #2c313a; }
.plug-led  { fill: var(--accent); }

.link-line {
  fill: none;
  stroke: var(--accent);
  stroke-width: 2.5;
  stroke-dasharray: 4 9;
  stroke-linecap: round;
  animation: dashflow 1.6s linear infinite;
}

.ring {
  fill: none;
  stroke: var(--accent);
  stroke-width: 2;
  opacity: 0;
  transform-origin: 220px 140px;
  animation: ripple 2.8s ease-out infinite;
}
.r2 { animation-delay: 0.5s; }
.r3 { animation-delay: 1s; }

.glow        { animation: pulse 2.8s ease-in-out infinite; }
.glow-delay  { animation: pulse 2.8s ease-in-out infinite 0.25s; }
.glow-delay2 { animation: pulse 2.8s ease-in-out infinite 0.35s; }
.glow-delay3 { animation: ledpulse 2.8s ease-in-out infinite 0.45s; }

.art-label {
  font-family: var(--font);
  font-size: 17px;
  font-weight: 700;
  fill: var(--ink);
  text-anchor: middle;
}
.art-sublabel {
  font-family: var(--font);
  font-size: 14px;
  fill: var(--ink-soft);
  text-anchor: middle;
}

@keyframes ripple {
  0%   { opacity: 0.55; transform: scale(0.55); }
  100% { opacity: 0;    transform: scale(1.25); }
}
@keyframes dashflow { to { stroke-dashoffset: -26; } }
@keyframes pulse {
  0%, 100% { fill: var(--glow); }
  50%      { fill: #fff0c4; }
}
@keyframes ledpulse {
  0%, 100% { opacity: 1; }
  50%      { opacity: 0.35; }
}

/* ---------- idea section ---------- */

.idea-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 22px;
  margin-top: 48px;
}

.idea-card {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius);
  padding: 30px;
}
.idea-card h3 { color: var(--accent); font-size: 1.5rem; }
.idea-card p { color: var(--dark-soft); }

/* ---------- steps ---------- */

.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 26px;
  margin-top: 48px;
}

.step {
  background: var(--tint);
  border-radius: var(--radius);
  padding: 34px 28px;
}

.step-num {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--accent);
  color: #1d1503;
  font-weight: 800;
  font-size: 1.2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
}

.step p { color: var(--ink-soft); font-size: 0.98rem; }

/* ---------- cards (use cases & products) ---------- */

.cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 48px;
}

.card {
  background: var(--paper);
  border: 1px solid rgba(0, 0, 0, 0.07);
  border-radius: var(--radius);
  padding: 32px 28px;
  box-shadow: 0 1px 3px rgba(16, 19, 25, 0.05);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 28px rgba(16, 19, 25, 0.1);
}

.card-icon { font-size: 2rem; margin-bottom: 14px; }
.card p { color: var(--ink-soft); font-size: 0.98rem; }

/* products */
.products { grid-template-columns: repeat(3, 1fr); }

.product-tag {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-deep);
  background: #fff3d8;
  border-radius: 999px;
  padding: 5px 12px;
  margin-bottom: 16px;
}

.tag-future { color: #5b6472; background: #e8ebf0; }

.product-future { border-style: dashed; }

/* ---------- promise ---------- */

.promise-list {
  list-style: none;
  margin-top: 40px;
  display: grid;
  gap: 18px;
}

.promise-list li {
  padding: 22px 26px;
  background: rgba(255, 255, 255, 0.05);
  border-left: 3px solid var(--accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: var(--dark-soft);
}
.promise-list strong { color: #fff; display: block; margin-bottom: 4px; }

/* ---------- specs ---------- */

.specs {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  margin-top: 48px;
}

.spec {
  border-top: 3px solid var(--accent);
  padding-top: 20px;
}

.spec-big {
  font-size: 1.45rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}

.spec p { color: var(--ink-soft); font-size: 0.95rem; }

/* ---------- signup ---------- */

.section-cta {
  background:
    radial-gradient(900px 400px at 50% 120%, #fff3d8 0%, transparent 70%),
    var(--tint);
}

.signup-form {
  display: flex;
  gap: 12px;
  justify-content: center;
  margin-top: 2rem;
  flex-wrap: wrap;
}

.signup-form input {
  font-family: var(--font);
  font-size: 1rem;
  padding: 14px 20px;
  border-radius: 999px;
  border: 1.5px solid rgba(0, 0, 0, 0.18);
  min-width: 290px;
  outline: none;
}
.signup-form input:focus { border-color: var(--accent-deep); }

.signup-done {
  margin-top: 1.4rem;
  font-weight: 700;
  color: var(--accent-deep);
}

/* ---------- FAQ ---------- */

.faq-list { margin-top: 40px; display: grid; gap: 12px; }

details {
  background: var(--tint);
  border-radius: 12px;
  padding: 20px 24px;
}

summary {
  cursor: pointer;
  font-weight: 700;
  font-size: 1.05rem;
  list-style: none;
  position: relative;
  padding-right: 32px;
}
summary::-webkit-details-marker { display: none; }
summary::after {
  content: "+";
  position: absolute;
  right: 4px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1.4rem;
  font-weight: 400;
  color: var(--accent-deep);
  transition: transform 0.2s ease;
}
details[open] summary::after { transform: translateY(-50%) rotate(45deg); }

details p { margin-top: 12px; color: var(--ink-soft); }

/* ---------- footer ---------- */

.footer {
  background: var(--dark);
  color: var(--dark-soft);
  padding: 64px 0;
  text-align: center;
}

.footer .logo { color: #fff; }
.footer-tag { margin: 10px 0 26px; font-weight: 600; color: #fff; }
.footer-fine { font-size: 0.85rem; line-height: 1.8; }

/* ---------- scroll reveal ---------- */

.reveal {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.visible { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  .ring, .link-line, .glow, .glow-delay, .glow-delay2, .glow-delay3 { animation: none; }
  html { scroll-behavior: auto; }
}

/* ---------- responsive ---------- */

@media (max-width: 900px) {
  .steps, .cards, .products { grid-template-columns: 1fr 1fr; }
  .specs { grid-template-columns: 1fr 1fr; }
  .nav-links { display: none; }
}

@media (max-width: 600px) {
  .section { padding: 72px 0; }
  .steps, .cards, .products, .specs, .idea-grid { grid-template-columns: 1fr; }
  .hero { padding-top: 80px; }
  .signup-form input { min-width: 0; width: 100%; }
}