/* Taipo Chat landing page
   Visual direction: editorial specimen meets precision instrument.
   See docs/experience-principles.md for rationale. */

/* ---------- Fonts (self-hosted; see assets/fonts/) ---------- */
@font-face {
  font-family: "Fraunces";
  src: url("fonts/fraunces-variable.woff2") format("woff2");
  font-weight: 100 900;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "Inter";
  src: url("fonts/inter-variable.woff2") format("woff2");
  font-weight: 100 900;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "JetBrains Mono";
  src: url("fonts/jetbrains-mono-variable.woff2") format("woff2");
  font-weight: 100 800;
  font-style: normal;
  font-display: swap;
}

/* ---------- Tokens ---------- */
:root {
  --paper: #ffffff;
  --paper-2: #f6f6f2;
  --ink: #15130f;
  --graphite: #56534d;
  --accent: #326e2f;        /* Approve / addition green from the logo */
  --accent-ink: #245421;
  --diff-red: #cb0b0a;
  --hairline: #d8d8d0;

  --serif: "Fraunces", Georgia, "Times New Roman", serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --wrap: 1100px;
  --gap: clamp(1rem, 3vw, 2rem);
  --section-y: clamp(3.5rem, 8vw, 7rem);
  --radius: 14px;
}

/* ---------- Reset / base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.001ms !important; transition-duration: 0.001ms !important; }
}
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1.0625rem;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img, svg { max-width: 100%; display: block; }
a { color: var(--accent-ink); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
code { font-family: var(--mono); font-size: 0.9em; background: var(--paper-2); padding: 0.1em 0.35em; border-radius: 6px; }

.wrap { width: 100%; max-width: var(--wrap); margin-inline: auto; padding-inline: clamp(1.1rem, 4vw, 2rem); }

.skip-link {
  position: absolute; left: -999px; top: 0; z-index: 100;
  background: var(--ink); color: var(--paper); padding: 0.6rem 1rem; border-radius: 0 0 8px 0;
}
.skip-link:focus { left: 0; }

:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; border-radius: 4px; }

/* ---------- Keyword + accents ---------- */
.kw {
  font-family: var(--mono);
  font-weight: 600;
  color: var(--accent-ink);
  background: rgba(50, 110, 47, 0.12);
  padding: 0.05em 0.4em;
  border-radius: 6px;
  font-size: 0.9em;
}
.accent { color: var(--accent-ink); }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  font-weight: 600; font-size: 1rem; line-height: 1;
  padding: 0.9rem 1.4rem; border-radius: 999px;
  text-decoration: none; border: 2px solid transparent; cursor: pointer;
  transition: transform 0.15s ease, background 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}
.btn-sm { padding: 0.55rem 1rem; font-size: 0.95rem; }
.btn-primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.btn-primary:hover { background: var(--accent-ink); border-color: var(--accent-ink); transform: translateY(-1px); }
.btn-ghost { background: transparent; color: var(--ink); border-color: var(--ink); }
.btn-ghost:hover { background: var(--ink); color: var(--paper); transform: translateY(-1px); }

/* ---------- Header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: saturate(140%) blur(8px);
  border-bottom: 1px solid var(--hairline);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; min-height: 64px; }
.wordmark {
  display: inline-flex; align-items: baseline; gap: 0.35rem;
  font-size: 1.4rem; text-decoration: none; color: var(--ink);
}
.wordmark-name { font-family: var(--serif); font-weight: 600; letter-spacing: -0.01em; }
.wordmark-mark {
  width: 1.05em; height: 1.05em; max-width: 1.05em;
  flex-shrink: 0; margin: 0; align-self: center;
}
.wordmark-sub {
  font-family: var(--mono); font-size: 0.68em; text-transform: uppercase;
  letter-spacing: 0.1em; color: var(--graphite); line-height: 1;
}

.site-nav { display: flex; align-items: center; gap: clamp(0.9rem, 2.2vw, 1.8rem); }
.site-nav a { color: var(--ink); text-decoration: none; font-size: 0.97rem; }
.site-nav a:not(.btn):hover { color: var(--accent-ink); }

.nav-toggle { display: none; flex-direction: column; gap: 5px; background: none; border: 0; padding: 8px; cursor: pointer; }
.nav-toggle span { width: 24px; height: 2px; background: var(--ink); border-radius: 2px; transition: transform 0.2s ease, opacity 0.2s ease; }
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- Hero ---------- */
.hero { padding-block: clamp(3rem, 8vw, 6.5rem); }
.hero-grid { display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(220px, 0.55fr); gap: clamp(2rem, 6vw, 5rem); align-items: center; }
.eyebrow, .section-eyebrow {
  font-family: var(--mono); font-size: 0.8rem; text-transform: uppercase;
  letter-spacing: 0.14em; color: var(--graphite); margin: 0 0 1rem;
}
.hero-copy { container-type: inline-size; }
.hero-title {
  font-family: var(--serif); font-weight: 600;
  font-size: clamp(1.95rem, 10.5cqi, 4.2rem);
  line-height: 1.05;
  letter-spacing: -0.02em; margin: 0 0 1.4rem;
}
.hero-title-line { display: block; }
.hero-sub { font-size: clamp(1.05rem, 1.6vw, 1.25rem); color: #2c2922; max-width: 36ch; margin: 0 0 2rem; }
.cta-row { display: flex; flex-wrap: wrap; gap: 0.8rem; }
.cta-center { justify-content: center; }
.features-strip { list-style: none; display: flex; flex-wrap: wrap; gap: 0.5rem 1.4rem; padding: 0; margin: 2.2rem 0 0; }
.features-strip li { font-size: 0.9rem; color: var(--graphite); position: relative; padding-left: 1.1rem; }
.features-strip li::before { content: ""; position: absolute; left: 0; top: 0.55em; width: 6px; height: 6px; border-radius: 50%; background: var(--accent); }

/* Hero brand */
.hero-brand {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: clamp(220px, 28vw, 360px);
}
.hero-brand img {
  width: min(100%, 280px);
  max-width: min(100%, 280px);
  height: auto;
  filter: drop-shadow(0 22px 48px rgba(21, 19, 15, 0.10));
}

/* ---------- Sections ---------- */
.section { padding-block: var(--section-y); border-top: 1px solid var(--hairline); }
.section-alt { background: var(--paper-2); }
.section-title { font-family: var(--serif); font-weight: 600; font-size: clamp(1.9rem, 4vw, 3rem); line-height: 1.08; letter-spacing: -0.02em; margin: 0 0 1rem; }
.section-lead { font-size: clamp(1.05rem, 1.6vw, 1.2rem); color: #2c2922; max-width: 56ch; margin: 0 0 2.5rem; }
.two-col { display: grid; grid-template-columns: 0.9fr 1.1fr; gap: clamp(2rem, 5vw, 4rem); align-items: start; }
.center-col { text-align: center; display: flex; flex-direction: column; align-items: center; }
.center-col .section-lead { margin-inline: auto; }
.section-intro { max-width: 760px; }

/* Cards */
.cards { display: grid; gap: var(--gap); }
.cards-4 { grid-template-columns: repeat(4, 1fr); }
.card { background: #fff; border: 1px solid var(--hairline); border-radius: var(--radius); padding: 1.4rem; }
.card h3 { font-family: var(--serif); font-size: 1.2rem; margin: 0 0 0.5rem; }
.card p { margin: 0; color: var(--graphite); font-size: 0.97rem; }

/* Steps */
.steps { list-style: none; counter-reset: none; display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--gap); padding: 0; margin: 0 0 2.5rem; }
.step { background: #fff; border: 1px solid var(--hairline); border-radius: var(--radius); padding: 1.6rem; }
.section-alt .step { background: var(--paper); }
.step-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 2.2rem; height: 2.2rem; border-radius: 50%;
  background: var(--accent); color: #fff; font-family: var(--mono); font-weight: 700; margin-bottom: 0.9rem;
}
.step h3 { font-family: var(--serif); font-size: 1.35rem; margin: 0 0 0.5rem; }
.step p { margin: 0; color: #2c2922; }
.step-list { margin: 0; padding-left: 1.15rem; color: #2c2922; }
.step-list li + li { margin-top: 0.55rem; }

/* Diff demo */
.diff-demo { position: relative; background: #fff; border: 1px solid var(--hairline); border-radius: var(--radius); padding: 1.5rem; max-width: 520px; }
.section-alt .diff-demo { background: var(--paper); }
.diff-label { font-family: var(--mono); font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.1em; padding: 0.15rem 0.5rem; border-radius: 6px; }
.diff-label-before { color: var(--diff-red); background: rgba(215,64,43,0.1); margin-right: 0.5rem; }
.diff-label-after { color: var(--accent-ink); background: rgba(50,110,47,0.12); }
.diff-svg { margin-top: 0.8rem; }
.diff-before { fill: none; stroke: var(--diff-red); stroke-width: 4; stroke-dasharray: 6 6; opacity: 0.8; }
.diff-after { fill: none; stroke: var(--accent); stroke-width: 4; }

/* Demo */
.demo-section .section-lead { margin-bottom: 1.8rem; }
.demo-frame {
  width: min(72%, 52rem);
  margin: 0 auto 2rem;
}
.demo-frame video {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border: 1px solid var(--ink);
  border-radius: calc(var(--radius) + 4px);
  background: #000;
  box-shadow: 0 18px 48px rgba(21, 19, 15, 0.14);
}
.demo-frame figcaption { color: var(--graphite); font-size: 0.92rem; margin-top: 0.8rem; }
.compact-steps { margin-bottom: 0; }

/* Feature lists */
.feature-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 1.1rem; }
.feature-list li { position: relative; padding-left: 1.8rem; }
.feature-list li::before {
  content: ""; position: absolute; left: 0; top: 0.45em;
  width: 12px; height: 12px; border-radius: 50%;
  background: var(--accent); box-shadow: 0 0 0 4px rgba(50,110,47,0.15);
}
.feature-list strong { display: inline; }

/* Scope */
.scope-grid { display: grid; grid-template-columns: 1fr 1fr; gap: var(--gap); }
.scope-col { border: 1px solid var(--hairline); border-radius: var(--radius); padding: 1.6rem; background: #fff; }
.scope-col h3 { font-family: var(--serif); font-size: 1.4rem; margin: 0 0 1rem; }
.scope-col ul { margin: 0; padding: 0; list-style: none; display: grid; gap: 0.7rem; }
.scope-col li { position: relative; padding-left: 1.7rem; }
.scope-good li::before { content: "+"; position: absolute; left: 0; color: var(--accent-ink); font-weight: 700; font-family: var(--mono); }
.scope-not li::before { content: "\2013"; position: absolute; left: 0; color: var(--diff-red); font-weight: 700; font-family: var(--mono); }

/* FAQ */
.faq { display: grid; gap: 0.7rem; max-width: 760px; }
.faq details { background: #fff; border: 1px solid var(--hairline); border-radius: var(--radius); padding: 0 1.2rem; }
.faq summary { cursor: pointer; list-style: none; padding: 1.1rem 0; font-family: var(--serif); font-size: 1.2rem; font-weight: 600; display: flex; justify-content: space-between; align-items: center; gap: 1rem; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; font-family: var(--mono); color: var(--accent-ink); font-weight: 700; transition: transform 0.2s ease; }
.faq details[open] summary::after { transform: rotate(45deg); }
.faq details p { margin: 0 0 1.2rem; color: #2c2922; }

/* Final CTA */
.final-cta { background: var(--ink); color: var(--paper); text-align: center; }
.final-cta .section-title { color: var(--paper); }
.final-cta .section-lead { color: #d8d2c6; margin-inline: auto; }
.final-cta .btn-ghost { color: var(--paper); border-color: var(--paper); }
.final-cta .btn-ghost:hover { background: var(--paper); color: var(--ink); }

/* ---------- Footer ---------- */
.site-footer { background: var(--paper-2); border-top: 1px solid var(--hairline); padding-block: clamp(2.5rem, 5vw, 4rem) 1.5rem; }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1fr; gap: var(--gap); }
.footer-tag { color: var(--graphite); max-width: 30ch; margin: 0.8rem 0 0; }
.footer-col { display: flex; flex-direction: column; gap: 0.5rem; }
.footer-col h4 { font-family: var(--mono); font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.12em; color: var(--graphite); margin: 0 0 0.4rem; }
.footer-col a { color: var(--ink); text-decoration: none; }
.footer-col a:hover { color: var(--accent-ink); }
.footer-fine { margin-top: 2.5rem; padding-top: 1.5rem; border-top: 1px solid var(--hairline); }
.footer-fine p { color: var(--graphite); font-size: 0.85rem; margin: 0; }

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .two-col { grid-template-columns: 1fr; }
  .cards-4 { grid-template-columns: 1fr 1fr; }
  .steps { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .hero-grid { grid-template-columns: minmax(0, 1.1fr) minmax(160px, 0.45fr); gap: clamp(1.5rem, 4vw, 3rem); }
  .hero-brand { min-height: clamp(180px, 24vw, 260px); }
  .hero-brand img { width: min(100%, 240px); max-width: min(100%, 240px); }
}
@media (max-width: 760px) {
  .hero { padding-block: clamp(2.25rem, 7vw, 4rem); }
  .hero-grid { grid-template-columns: 1fr; gap: clamp(1.5rem, 6vw, 2.5rem); }
  .hero-brand { order: -1; min-height: auto; justify-content: flex-start; }
  .hero-brand img { width: min(44vw, 170px); max-width: min(44vw, 170px); }
  .demo-frame { width: 100%; }
}
@media (max-width: 640px) {
  .nav-toggle { display: flex; }
  .site-nav {
    position: absolute; top: 64px; left: 0; right: 0;
    flex-direction: column; align-items: stretch; gap: 0;
    background: var(--paper); border-bottom: 1px solid var(--hairline);
    padding: 0.5rem 1rem 1rem; transform: translateY(-8px); opacity: 0; pointer-events: none;
    transition: opacity 0.2s ease, transform 0.2s ease;
  }
  .site-nav.open { opacity: 1; transform: translateY(0); pointer-events: auto; }
  .site-nav a { padding: 0.7rem 0; border-bottom: 1px solid var(--hairline); }
  .site-nav a.btn { margin-top: 0.6rem; border-bottom: 0; }
  .cards-4, .scope-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
}