/* =========================================================================
   The Kori Letter: landing page styles
   Static, self-contained. No external fonts, scripts, or CDN dependencies.
   Theme-aware via prefers-color-scheme. Mobile-first, responsive.
   ========================================================================= */

/* ----- Design tokens ----- */
:root {
  --accent: #4f6ef7;
  --accent-hover: #3f5ce0;

  --bg: #ffffff;
  --bg-alt: #f5f6f8;
  --surface: #ffffff;
  --border: #e4e6eb;

  --text: #14161c;
  --text-soft: #4a4f5c;
  --text-faint: #5c6270;

  --shadow: 0 1px 2px rgba(20, 22, 28, 0.04), 0 8px 24px rgba(20, 22, 28, 0.06);

  --maxw: 720px;
  --radius: 12px;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --accent: #6b86ff;
    --accent-hover: #839aff;

    --bg: #0e1015;
    --bg-alt: #14171e;
    --surface: #171a22;
    --border: #262b36;

    --text: #f0f2f6;
    --text-soft: #b9bfcd;
    --text-faint: #838b9c;

    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 8px 24px rgba(0, 0, 0, 0.4);
  }
}

/* ----- Reset / base ----- */
* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3 { line-height: 1.2; letter-spacing: -0.01em; margin: 0; }

p { margin: 0; }

a { color: inherit; }

img { max-width: 100%; height: auto; }

.wrap {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 22px;
}

.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0);
  white-space: nowrap; border: 0;
}

/* ----- Buttons ----- */
.btn {
  display: inline-block;
  padding: 13px 22px;
  border-radius: 10px;
  font-size: 16px;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
  transition: background-color 0.15s ease, border-color 0.15s ease, transform 0.05s ease;
}
.btn:active { transform: translateY(1px); }

.btn-primary {
  background: var(--accent);
  color: #ffffff;
}
.btn-primary:hover { background: var(--accent-hover); }

.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}
.btn-ghost:hover { border-color: var(--text-faint); }

/* ----- Header ----- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-weight: 700;
  color: var(--text);
}
.brand-mark {
  display: grid;
  place-items: center;
  width: 28px; height: 28px;
  border-radius: 7px;
  background: var(--accent);
  color: #fff;
  font-weight: 700;
  font-size: 16px;
}
.brand-name { font-size: 16px; }
.header-cta {
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  color: var(--accent);
}
.header-cta:hover { color: var(--accent-hover); }

/* ----- Hero ----- */
.hero {
  padding: 84px 0 64px;
  text-align: center;
}
.kicker {
  display: inline-block;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 18px;
}
.hero-title {
  font-size: clamp(2rem, 6vw, 3.1rem);
  font-weight: 800;
  margin-bottom: 22px;
}
.hero-sub {
  font-size: clamp(1.05rem, 2.4vw, 1.2rem);
  color: var(--text-soft);
  max-width: 600px;
  margin: 0 auto 30px;
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin-bottom: 16px;
}
.hero-note {
  font-size: 14px;
  color: var(--text-faint);
}

/* ----- Sections ----- */
.section { padding: 62px 0; }
.section-alt { background: var(--bg-alt); }
.section-title {
  font-size: clamp(1.5rem, 4vw, 2rem);
  font-weight: 800;
  margin-bottom: 14px;
  text-align: center;
}
.section-lead {
  font-size: 1.1rem;
  color: var(--text-soft);
  text-align: center;
  max-width: 540px;
  margin: 0 auto 40px;
}

/* ----- What you'll get (cards) ----- */
.cards {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 16px;
  grid-template-columns: 1fr 1fr;
}
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}
.card h3 {
  font-size: 1.12rem;
  margin-bottom: 8px;
}
.card p {
  color: var(--text-soft);
  font-size: 0.98rem;
}

/* ----- Who ----- */
.who { max-width: 620px; }
.who .section-title { text-align: left; }
.who p {
  color: var(--text-soft);
  margin-bottom: 18px;
}
.who p:last-child { margin-bottom: 0; }

/* ----- Subscribe ----- */
.subscribe-inner { text-align: center; }
.signup-embed {
  max-width: 480px;
  margin: 0 auto;
}
.placeholder-form {
  display: flex;
  gap: 10px;
}
.placeholder-form input {
  flex: 1;
  min-width: 0;
  padding: 13px 16px;
  font-size: 16px;
  font-family: inherit;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
}
.placeholder-form input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 25%, transparent);
}
.placeholder-note {
  margin-top: 12px;
  font-size: 13px;
  color: var(--text-faint);
  font-style: italic;
}

/* ----- Footer ----- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 30px 0;
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 16px;
  align-items: center;
  justify-content: space-between;
  font-size: 14px;
  color: var(--text-faint);
}
.footer-inner span:first-child { font-weight: 600; color: var(--text-soft); }

/* ----- Responsive ----- */
@media (max-width: 560px) {
  .cards { grid-template-columns: 1fr; }
  .hero { padding: 60px 0 48px; }
  .placeholder-form { flex-direction: column; }
  .placeholder-form .btn { width: 100%; }
}

/* ----- Motion / accessibility ----- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; }
}