/* =========================================================================
   lazy-html intro page · Material Design 3 baseline
   Pure CSS, no preprocessor, no build step. Simple two-section explainer.
   ========================================================================= */

/* ---- MD3 design tokens : LIGHT (default) ---- */
:root,
[data-theme="light"] {
  --primary:            #6750A4;
  --on-primary:         #FFFFFF;
  --primary-container:  #EADDFF;
  --on-primary-container:#21005D;
  --secondary:          #625B71;
  --secondary-container:#E8DEF8;
  --on-secondary-container:#1D192B;

  --background:         #FEF7FF;
  --on-background:      #1D1B20;
  --surface:            #FEF7FF;
  --surface-container:  #F3EDF7;
  --surface-container-high:#ECE6F0;
  --surface-variant:    #E7E0EC;
  --on-surface:         #1D1B20;
  --on-surface-variant: #49454F;

  --outline:            #79747E;
  --outline-variant:    #CAC4D0;

  --elev-1: 0 1px 2px rgba(0,0,0,.10), 0 1px 3px 1px rgba(0,0,0,.06);
  --elev-2: 0 2px 6px 2px rgba(0,0,0,.10), 0 1px 2px rgba(0,0,0,.12);

  --radius-sm: 12px;
  --radius:    20px;
  --radius-lg: 28px;
  --radius-pill: 999px;

  --maxw: 760px;
  --font-body: "Roboto Flex", "Roboto", system-ui, sans-serif;
}

/* ---- MD3 design tokens : DARK ---- */
[data-theme="dark"] {
  --primary:            #D0BCFF;
  --on-primary:         #381E72;
  --primary-container:  #4F378B;
  --on-primary-container:#EADDFF;
  --secondary:          #CCC2DC;
  --secondary-container:#4A4458;
  --on-secondary-container:#E8DEF8;

  --background:         #141218;
  --on-background:      #E6E0E9;
  --surface:            #141218;
  --surface-container:  #211F26;
  --surface-container-high:#2B2930;
  --surface-variant:    #49454F;
  --on-surface:         #E6E0E9;
  --on-surface-variant: #CAC4D0;

  --outline:            #938F99;
  --outline-variant:    #49454F;

  --elev-1: 0 1px 2px rgba(0,0,0,.30), 0 1px 3px 1px rgba(0,0,0,.20);
  --elev-2: 0 2px 6px 2px rgba(0,0,0,.30), 0 1px 2px rgba(0,0,0,.30);
}

/* ---- Reset / base ---- */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-body);
  background: var(--background);
  color: var(--on-background);
  -webkit-font-smoothing: antialiased;
  line-height: 1.65;
  transition: background .2s, color .2s;
}
a { color: var(--primary); text-decoration: none; }
.material-symbols-rounded {
  font-variation-settings: "FILL" 0, "wght" 400, "GRAD" 0, "opsz" 24;
  line-height: 1;
  user-select: none;
}

/* ---- App bar ---- */
.appbar {
  position: sticky;
  top: 0;
  z-index: 20;
  background: color-mix(in srgb, var(--surface-container) 90%, transparent);
  backdrop-filter: blur(8px);
  box-shadow: var(--elev-1);
}
.appbar__inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 10px 20px;
  display: flex;
  align-items: center;
  gap: 12px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--on-surface);
}
.brand__logo { color: var(--primary); }
.appbar__actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 8px;
}
.icon-btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  border: none;
  background: transparent;
  color: var(--on-surface-variant);
  border-radius: var(--radius-pill);
  padding: 8px 10px;
  cursor: pointer;
  font: inherit;
  transition: background .15s;
}
.icon-btn:hover { background: var(--surface-container-high); }
.icon-btn__txt { font-size: .85rem; font-weight: 600; }

/* ---- Shared layout ---- */
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }

/* ---- Hero ---- */
.hero {
  text-align: center;
  padding: 64px 20px 40px;
}
.hero__eyebrow {
  display: inline-block;
  margin-bottom: 16px;
  padding: 6px 14px;
  border-radius: var(--radius-pill);
  background: var(--secondary-container);
  color: var(--on-secondary-container);
  font-size: .85rem;
  font-weight: 600;
}
.hero__title {
  margin: 0 0 14px;
  font-size: clamp(2.4rem, 7vw, 3.6rem);
  font-weight: 700;
  line-height: 1.05;
  letter-spacing: -.02em;
  color: var(--on-surface);
}
.hero__subtitle {
  margin: 0 auto;
  max-width: 34ch;
  font-size: clamp(1.05rem, 2.4vw, 1.3rem);
  color: var(--on-surface-variant);
}
.hero__actions {
  margin-top: 32px;
  display: flex;
  justify-content: center;
}
.hero__note {
  margin: 16px 0 0;
  font-size: .85rem;
  color: var(--on-surface-variant);
}

/* ---- Buttons (MD3 filled + tonal) ---- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 15px 30px;
  border: none;
  border-radius: var(--radius-pill);
  font: inherit;
  font-weight: 700;
  font-size: 1.05rem;
  cursor: pointer;
  transition: box-shadow .18s, transform .18s, filter .18s;
}
.btn .material-symbols-rounded { font-size: 22px; }
.btn--filled {
  background: var(--primary);
  color: var(--on-primary);
  box-shadow: var(--elev-1);
}
.btn--filled:hover { box-shadow: var(--elev-2); transform: translateY(-2px); filter: brightness(1.05); }
.btn--tonal {
  background: var(--secondary-container);
  color: var(--on-secondary-container);
  font-size: .98rem;
  padding: 13px 26px;
}
.btn--tonal:hover { box-shadow: var(--elev-1); transform: translateY(-2px); }
.btn:focus-visible { outline: 2px solid var(--primary); outline-offset: 3px; }

/* ---- Content blocks ---- */
main { padding-bottom: 24px; }
.block { padding: 36px 20px; }
.block + .block { border-top: 1px solid var(--outline-variant); }
.block__inner { max-width: var(--maxw); margin: 0 auto; }
.block h2 {
  margin: 0 0 8px;
  font-size: clamp(1.6rem, 4vw, 2rem);
  font-weight: 700;
  letter-spacing: -.01em;
  color: var(--on-surface);
}
.block h2 .material-symbols-rounded {
  font-size: 1.1em;
  color: var(--primary);
  vertical-align: -.15em;
  margin-right: 6px;
}
.block p { color: var(--on-surface-variant); font-size: 1.08rem; margin: 0 0 14px; }
.block p:last-child { margin-bottom: 0; }

/* ---- "What is it" benefit chips ---- */
.benefits {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}
.benefit {
  background: var(--surface-container);
  border-radius: var(--radius);
  padding: 20px 18px;
  text-align: center;
}
.benefit .material-symbols-rounded {
  font-size: 32px;
  color: var(--primary);
  display: block;
  margin: 0 auto 10px;
}
.benefit b { display: block; color: var(--on-surface); font-size: 1rem; margin-bottom: 4px; }
.benefit span { color: var(--on-surface-variant); font-size: .9rem; }

/* ---- "How it works" flow ---- */
.flow {
  margin: 28px 0 0;
  display: flex;
  align-items: stretch;
  justify-content: center;
  gap: 10px;
}
.flow__step {
  flex: 1 1 0;
  position: relative;
  background: var(--surface-container);
  border-radius: var(--radius);
  padding: 26px 16px 20px;
  text-align: center;
}
.flow__num {
  position: absolute;
  top: -13px;
  left: 50%;
  transform: translateX(-50%);
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--primary);
  color: var(--on-primary);
  font-weight: 700;
  font-size: .9rem;
  display: grid;
  place-items: center;
  box-shadow: var(--elev-1);
}
.flow__icon {
  font-size: 34px;
  color: var(--primary);
  display: block;
  margin: 2px auto 10px;
}
.flow__step b { display: block; color: var(--on-surface); font-size: 1.02rem; margin-bottom: 4px; }
.flow__desc { color: var(--on-surface-variant); font-size: .9rem; }
.flow__arrow {
  align-self: center;
  flex: 0 0 auto;
  font-size: 28px;
  color: var(--outline);
}

/* ---- "How to use" steps ---- */
.steps {
  list-style: none;
  counter-reset: step;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}
.steps li {
  counter-increment: step;
  position: relative;
  background: var(--surface-container);
  border-radius: var(--radius);
  padding: 18px 20px 18px 64px;
  color: var(--on-surface);
  font-size: 1.05rem;
}
.steps li::before {
  content: counter(step);
  position: absolute;
  left: 16px;
  top: 16px;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--primary);
  color: var(--on-primary);
  font-weight: 700;
  display: grid;
  place-items: center;
}
.steps li b { color: var(--on-surface); }
.steps li .hint { display: block; margin-top: 4px; color: var(--on-surface-variant); font-size: .92rem; }

/* ---- Screenshot ---- */
.shot {
  margin: 24px 0 0;
  padding: 0;
}
.shot img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: var(--radius);
  border: 1px solid var(--outline-variant);
  box-shadow: var(--elev-2);
}
.shot figcaption {
  margin-top: 10px;
  text-align: center;
  font-size: .88rem;
  color: var(--on-surface-variant);
}

.block__cta { margin-top: 28px; text-align: center; }

/* ---- Footer ---- */
.footer {
  text-align: center;
  padding: 40px 20px 56px;
  border-top: 1px solid var(--outline-variant);
  color: var(--on-surface-variant);
  font-size: .95rem;
}
.footer__name { margin: 0 0 8px; }
.footer__links { margin: 0; }
.footer a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-weight: 700;
  color: var(--primary);
}
.footer a:hover { text-decoration: underline; }
.footer .material-symbols-rounded { font-size: 18px; }

/* ---- Responsive ---- */
@media (max-width: 560px) {
  .hero { padding-top: 44px; }
  .benefits { grid-template-columns: 1fr; }
  .flow { flex-direction: column; gap: 8px; }
  .flow__arrow { transform: rotate(90deg); }
}