/* ============================================================
   COROLLARY TUTORS — styles.css
   Palette: bone / ink / signal orange / diagram teal / rule gray
   Type: IBM Plex Serif (display) · Plex Sans (body) · Plex Mono (technical)
   Mark: three-dot therefore (∴) in Signal Orange
============================================================ */

/* ── Tokens ──────────────────────────────────────────────── */

:root {
  --bone: #F4EFE4;
  --bone-warm: #FAF6EC;
  --ink: #1E1A17;
  --ink-secondary: rgba(30, 26, 23, 0.65);
  --ink-muted: rgba(30, 26, 23, 0.45);
  --signal: #D4633A;
  --signal-dark: #B54F2A;
  --diagram: #4A7C7E;
  --rule: #C9C0B0;

  --font-serif: 'IBM Plex Serif', Georgia, serif;
  --font-sans: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'IBM Plex Mono', ui-monospace, SFMono-Regular, monospace;

  --fs-mono: 0.75rem;
  --fs-small: 0.9375rem;
  --fs-body: 1.0625rem;
  --fs-h2: 1.75rem;
  --fs-h1: 2.5rem;
  --fs-display: 3.5rem;

  --max-w: 1080px;
  --content-w: 680px;
  --pad-side: 24px;

  --dur-fast: 0.15s;
  --dur-base: 0.25s;
  --dur-slow: 0.4s;
}

@media (min-width: 640px) {
  :root {
    --fs-display: 4.5rem;
    --fs-h1: 3rem;
    --pad-side: 40px;
  }
}

@media (min-width: 960px) {
  :root {
    --fs-display: 5.5rem;
    --fs-h1: 3.5rem;
    --pad-side: 64px;
  }
}

/* ── Reset & base ────────────────────────────────────────── */

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  scroll-padding-top: 80px;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  line-height: 1.6;
  color: var(--ink);
  background: var(--bone);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: inherit; text-decoration: none; }

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

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

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

.skip-link {
  position: absolute;
  top: -100px;
  left: 16px;
  z-index: 200;
  padding: 12px 20px;
  background: var(--ink);
  color: var(--bone);
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  transition: top var(--dur-fast) ease;
}

.skip-link:focus { top: 16px; }

:focus-visible {
  outline: 2px solid var(--signal);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ── Utility ─────────────────────────────────────────────── */

.mono {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

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

.eyebrow {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--signal);
  margin: 0 0 20px;
}

.eyebrow--small {
  font-size: 0.6875rem;
  letter-spacing: 0.18em;
  color: var(--ink-secondary);
  margin-bottom: 16px;
}

/* ── Nav ─────────────────────────────────────────────────── */

.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(244, 239, 228, 0.88);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--rule);
}

.nav__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 14px var(--pad-side);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.nav__wordmark {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 1.0625rem;
  letter-spacing: -0.02em;
  color: var(--ink);
  flex-shrink: 0;
}

.nav__mark {
  display: inline-block;
  width: 12px;
  height: 12px;
  color: var(--signal);
}

.nav__links {
  display: none;
  gap: 32px;
  list-style: none;
  margin: 0;
  padding: 0;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
}

.nav__links a {
  color: var(--ink-secondary);
  transition: color var(--dur-fast) ease;
}

.nav__links a:hover { color: var(--ink); }

@media (min-width: 820px) { .nav__links { display: flex; } }

.nav__cta {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  padding: 8px 16px;
  border: 1px solid var(--ink);
  color: var(--ink);
  border-radius: 4px;
  transition: background var(--dur-fast) ease, color var(--dur-fast) ease;
  flex-shrink: 0;
}

.nav__cta:hover {
  background: var(--ink);
  color: var(--bone);
}

/* ── Hero ────────────────────────────────────────────────── */

.hero {
  min-height: calc(100vh - 60px);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 80px var(--pad-side) 60px;
  text-align: center;
  position: relative;
}

.hero__inner {
  max-width: 720px;
  width: 100%;
  transform: translateY(-3rem); /* Negative values move it UP */
}

.hero__mark {
  color: var(--signal);
  width: 68px;
  height: 68px;
  margin: 0 auto 36px;
}

.hero__dot {
  opacity: 0;
  transform-origin: center;
  transform-box: fill-box;
  animation: dotAppear 0.4s cubic-bezier(0.2, 0.7, 0.3, 1) forwards;
}

.hero__dot--1 { animation-delay: 0.15s; }
.hero__dot--2 { animation-delay: 0.30s; }
.hero__dot--3 { animation-delay: 0.45s; }

@keyframes dotAppear {
  from { opacity: 0; transform: scale(0.6); }
  to { opacity: 1; transform: scale(1); }
}

.hero__wordmark {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: var(--fs-display);
  letter-spacing: -0.03em;
  line-height: 1;
  margin: 0 0 24px;
  color: var(--ink);
  opacity: 0;
  animation: fadeInUp 0.6s ease 0.65s forwards;
}

.hero__tagline {
  font-family: var(--font-mono);
  font-size: 0.9375rem;
  letter-spacing: 0.02em;
  color: var(--ink-secondary);
  margin: 0 0 44px;
  opacity: 0;
  animation: fadeInUp 0.6s ease 0.85s forwards;
}

@media (min-width: 640px) {
  .hero__tagline { font-size: 1.0625rem; }
}

.hero .btn {
  opacity: 0;
  animation: fadeInUp 0.6s ease 1.05s forwards;
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.hero__scroll-cue {
  position: absolute;
  bottom: 50px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: var(--ink-muted);
  opacity: 0;
  animation: fadeIn 0.6s ease 1.4s forwards, bob 2.4s ease-in-out 2.4s infinite;
}

.hero__scroll-cue .mono {
  font-size: 0.625rem;
  letter-spacing: 0.2em;
}

@keyframes fadeIn { to { opacity: 1; } }

@keyframes bob {
  0%, 100% { transform: translateX(-50%) translateY(0); opacity: 1; }
  50%      { transform: translateX(-50%) translateY(6px); opacity: 0.6; }
}

/* Hero sketch animation
   Sits between the CTA and the scroll cue. 16:9, max 560px, fades in
   after the hero cascade settles. */
.hero__animation {
  width: 100%;
  max-width: 560px;
  margin: 1.25rem auto 1rem;
  opacity: 0;
  transform: translateY(6px);
  transition: opacity 700ms ease, transform 700ms ease;
}
.hero__animation-frame {
  aspect-ratio: 16 / 9;
  width: 100%;
}
.hero__animation-frame svg {
  width: 100%;
  height: 100%;
  display: block;
}
.hero__animation-frame.is-playing {
  /* the JS adds is-playing right before the animation starts, which
     triggers the container fade-in. Keeps the entrance in sync with
     the animation kickoff without JS having to touch inline styles. */
}
.hero__animation:has(.is-playing) {
  opacity: 1;
  transform: none;
}

/* Mobile: shrink margin so the animation doesn't push the scroll cue
   too far down. */
@media (max-width: 640px) {
  .hero__animation { margin-top: 2rem; max-width: 100%; }
}

/* Respect reduced motion — no fade transition, show final frame from
   the start. The JS already jumps to the settled last frame in this
   case; here we just make the container appear immediately. */
@media (prefers-reduced-motion: reduce) {
  .hero__animation {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* ── Buttons ─────────────────────────────────────────────── */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--font-sans);
  font-weight: 500;
  border-radius: 4px;
  transition: background var(--dur-fast) ease, color var(--dur-fast) ease, transform var(--dur-fast) ease;
  text-align: center;
}

.btn--primary {
  background: var(--signal);
  color: #FFFFFF;
  padding: 13px 26px;
  font-size: 0.9375rem;
  letter-spacing: 0.01em;
}

.btn--primary:hover {
  background: var(--signal-dark);
  transform: translateY(-1px);
}

.btn--secondary {
  background: var(--ink);
  color: var(--bone);
  padding: 11px 22px;
  font-size: 0.875rem;
}

.btn--secondary:hover { background: var(--signal); }

.btn--large { padding: 16px 32px; font-size: 1rem; }

/* ── Section divider ─────────────────────────────────────── */

.section-divider {
  display: flex;
  justify-content: center;
  padding: 16px 0;
  color: var(--signal);
  opacity: 0.55;
}

.section-divider svg {
  width: 20px;
  height: 20px;
}

/* ── Section base ────────────────────────────────────────── */

.section {
  padding: 96px var(--pad-side);
}

@media (min-width: 640px) {
  .section { padding: 120px var(--pad-side); }
}

.section__inner {
  max-width: var(--max-w);
  margin: 0 auto;
}

.section__heading {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: var(--fs-h1);
  letter-spacing: -0.025em;
  line-height: 1.05;
  color: var(--ink);
  margin: 0 0 48px;
  max-width: 24ch;
}

/* ── Prose ───────────────────────────────────────────────── */

.prose {
  max-width: var(--content-w);
}

.prose p {
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  line-height: 1.7;
  color: var(--ink);
  margin: 0 0 20px;
}

.prose p:last-child { margin-bottom: 0; }

/* ── Subjects ────────────────────────────────────────────── */

.subjects-grid {
  display: flex;
  flex-direction: column;
  max-width: 900px;
  border-top: 1px solid var(--rule);
}

.subject-row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 8px;
  padding: 24px 0;
  border-bottom: 1px solid var(--rule);
}

.subject-row__label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--signal);
}

.subject-row__list {
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  color: var(--ink);
  line-height: 1.5;
}

@media (min-width: 780px) {
  .subject-row {
    grid-template-columns: 220px 1fr;
    gap: 32px;
    align-items: baseline;
  }
}

.subjects-note {
  margin-top: 32px;
  color: var(--ink-secondary);
  letter-spacing: 0.02em;
  text-transform: none;
  font-size: 0.8125rem;
  max-width: 600px;
}

/* ── About ───────────────────────────────────────────────── */

.about-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
  max-width: 1000px;
}

@media (min-width: 780px) {
  .about-layout {
    grid-template-columns: 240px 1fr;
    gap: 56px;
  }
}

.about-layout__photo { width: 100%; max-width: 260px; }

.photo-placeholder {
  aspect-ratio: 4 / 5;
  border: 1px dashed var(--rule);
  border-radius: 4px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  color: var(--ink-muted);
  background: var(--bone-warm);
}

.photo-placeholder__sub {
  font-size: 0.625rem;
  letter-spacing: 0.14em;
  opacity: 0.7;
}

.about-layout__text .about-layout__coda {
  font-family: var(--font-serif);
  font-style: italic;
  font-size: 1.1875rem;
  line-height: 1.5;
  color: var(--ink);
  padding-top: 24px;
  margin-top: 20px;
  border-top: 1px solid var(--rule);
  max-width: var(--content-w);
}

/* ── Public ──────────────────────────────────────────────── */

.public-content {
  display: flex;
  flex-direction: column;
  gap: 56px;
  max-width: var(--content-w);
}

.public-block {}

.socials {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
}

@media (min-width: 640px) {
  .socials { grid-template-columns: repeat(3, 1fr); }
}

.social-btn {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 16px 20px;
  border: 1px solid var(--rule);
  border-radius: 6px;
  background: var(--bone-warm);
  transition: border-color var(--dur-fast) ease, transform var(--dur-fast) ease;
}

.social-btn:hover {
  border-color: var(--ink);
  transform: translateY(-1px);
}

.social-btn__label {
  font-family: var(--font-sans);
  font-weight: 500;
  font-size: 0.9375rem;
  color: var(--ink);
}

.social-btn__handle {
  color: var(--ink-secondary);
  text-transform: none;
  font-size: 0.75rem;
  letter-spacing: 0.02em;
}

/* ── Submit form ─────────────────────────────────────────── */

.submit-form {
  border: 1px solid var(--rule);
  border-radius: 6px;
  background: var(--bone-warm);
  padding: 8px 12px;
  transition: border-color var(--dur-fast) ease;
}

.submit-form:focus-within { border-color: var(--ink); }

.submit-form__input {
  width: 100%;
  border: none;
  background: transparent;
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  color: var(--ink);
  resize: vertical;
  min-height: 92px;
  outline: none;
  padding: 10px 6px;
  line-height: 1.55;
}

.submit-form__input::placeholder,
.submit-form__email::placeholder { color: var(--ink-muted); }

.submit-form__footer {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 10px 4px 6px;
  border-top: 1px solid var(--rule);
}

@media (min-width: 640px) {
  .submit-form__footer {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
  }
}

.submit-form__email {
  flex: 1;
  min-width: 0;
  border: none;
  background: transparent;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--ink);
  outline: none;
  padding: 6px 4px;
}

.form-status {
  margin-top: 12px;
  color: var(--diagram);
  text-transform: none;
  letter-spacing: 0.02em;
  font-size: 0.8125rem;
  min-height: 20px;
}

/* ── Book ────────────────────────────────────────────────── */

.section--book { background: var(--bone-warm); }

.book-content { margin-bottom: 40px; }

.book-content .signal {
  font-weight: 500;
  font-family: var(--font-mono);
  font-size: 0.95em;
}

.book-cta {
  display: flex;
  flex-direction: column;
  gap: 14px;
  align-items: flex-start;
}

.book-cta__sub {
  color: var(--ink-secondary);
  letter-spacing: 0.05em;
  text-transform: none;
  font-size: 0.8125rem;
}

.book-cta__sub a {
  color: var(--ink);
  border-bottom: 1px solid var(--rule);
  transition: border-color var(--dur-fast) ease;
}

.book-cta__sub a:hover { border-color: var(--ink); }

/* ── Footer ──────────────────────────────────────────────── */

.footer {
  padding: 48px var(--pad-side);
  border-top: 1px solid var(--rule);
  background: var(--bone);
}

.footer__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 20px;
  align-items: center;
  text-align: center;
}

@media (min-width: 780px) {
  .footer__inner {
    flex-direction: row;
    justify-content: space-between;
    text-align: left;
  }
}

.footer__tagline {
  color: var(--ink);
  letter-spacing: 0.02em;
  text-transform: none;
  font-size: 0.875rem;
}

.footer__tagline .signal { font-weight: 500; }

.footer__meta {
  color: var(--ink-secondary);
  letter-spacing: 0.06em;
  font-size: 0.6875rem;
  text-transform: none;
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
}

.footer__meta a { color: var(--ink); }

.footer__meta a:hover { color: var(--signal); }

/* ── Reduced motion ──────────────────────────────────────── */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .hero__dot, .hero__wordmark, .hero__tagline, .hero .btn, .hero__scroll-cue {
    opacity: 1;
  }
  html { scroll-behavior: auto; }
}