/* =============================================================
   Stu Landing Page — styles.css
   Design system: dark-first, calm, grounded
   ============================================================= */

/* --- Design Tokens ------------------------------------------ */
:root {
  --bg:             #1F2A24;
  --surface:        #26352E;
  --divider:        #31423A;
  --text-primary:   #F5F4EA;
  --text-secondary: #A8B2A9;
  --text-muted:     #7F8A83;
  --accent:         #6F8A78;
  --danger:         #C96A4A;

  --max-width: 720px;
  --radius: 10px;
  --radius-sm: 6px;
}

/* --- Reset --------------------------------------------------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

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

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

ul {
  list-style: none;
}

/* --- Base Typography ----------------------------------------- */
body {
  background-color: var(--bg);
  color: var(--text-primary);
  font-family: 'EB Garamond', Georgia, 'Times New Roman', serif;
  font-size: 1.125rem; /* 18px */
  line-height: 1.65;
  min-height: 100vh;
}

h1, h2, h3, h4, h5, h6 {
  font-family: 'IBM Plex Sans', 'Helvetica Neue', Arial, sans-serif;
  color: var(--text-primary);
  line-height: 1.2;
  font-weight: 600;
}

h1 { font-size: clamp(2rem, 5vw, 3rem); font-weight: 700; }
h2 { font-size: clamp(1.5rem, 3.5vw, 2rem); }
h3 { font-size: 1.25rem; }

p {
  color: var(--text-secondary);
  max-width: 60ch;
}

/* --- Layout -------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: 24px;
}

section {
  padding-block: 80px;
}

section + section {
  border-top: 1px solid var(--divider);
}

/* --- Navigation --------------------------------------------- */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--bg);
  border-bottom: 1px solid var(--divider);
  padding-block: 16px;
}

.site-nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-family: 'IBM Plex Sans', sans-serif;
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.nav-logo:hover {
  text-decoration: none;
  color: var(--text-primary);
}

.nav-links {
  display: flex;
  gap: 32px;
  align-items: center;
}

.nav-links a {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.nav-links a:hover {
  color: var(--text-primary);
  text-decoration: none;
}

/* --- Buttons ------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 12px 24px;
  border-radius: 22px;
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.9375rem;
  font-weight: 500;
  cursor: pointer;
  border: none;
  text-decoration: none;
  transition: opacity 0.15s ease;
}

.btn:hover {
  opacity: 0.85;
  text-decoration: none;
}

.btn-primary {
  background-color: var(--accent);
  color: var(--bg);
}

.btn-secondary {
  background-color: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--divider);
}

/* --- Hero ---------------------------------------------------- */
.hero {
  padding-block: 96px 80px;
}

.hero .container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}

.hero-content {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.hero-eyebrow {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero h1 {
  color: var(--text-primary);
}

.hero-sub {
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 44ch;
}

.hero-cta {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 8px;
}

.hero-visual {
  display: flex;
  align-items: center;
  justify-content: center;
}

.mascot-placeholder {
  width: 240px;
  height: 300px;
  background-color: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--divider);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
}

.mascot-placeholder svg {
  opacity: 0.6;
}

.mascot-placeholder span {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.75rem;
  color: var(--text-muted);
  letter-spacing: 0.05em;
}

/* --- Problem ------------------------------------------------- */
.problem {
  text-align: center;
}

.problem .container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

.section-label {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.problem h2 {
  max-width: 22ch;
}

.problem p {
  max-width: 52ch;
  text-align: center;
  margin-inline: auto;
}

/* --- How Stu Works ------------------------------------------ */
.how-it-works .container {
  display: flex;
  flex-direction: column;
  gap: 48px;
}

.how-it-works-header {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

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

.step {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.step-number {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.05em;
}

.step h3 {
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--text-primary);
}

.step p {
  font-size: 1rem;
  color: var(--text-secondary);
  max-width: none;
}

.step-connector {
  display: none; /* shown on desktop via ::after if desired */
}

/* --- Product View ------------------------------------------- */
.product-view .container {
  display: flex;
  flex-direction: column;
  gap: 48px;
}

.product-view-header {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.screenshots {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  align-items: start;
}

.screenshot-frame {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.screenshot-placeholder {
  width: 100%;
  aspect-ratio: 9 / 19.5;
  background-color: var(--surface);
  border-radius: 20px;
  border: 1px solid var(--divider);
  display: flex;
  align-items: center;
  justify-content: center;
}

.screenshot-placeholder span {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.6875rem;
  color: var(--text-muted);
  letter-spacing: 0.05em;
  text-align: center;
  padding: 8px;
}

.screenshot-caption {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.875rem;
  color: var(--text-secondary);
  text-align: center;
  max-width: none;
}

/* --- What Stu Is / Is Not ------------------------------------ */
.scope .container {
  display: flex;
  flex-direction: column;
  gap: 40px;
}

.scope-header {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.scope-columns {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.scope-column {
  background-color: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--divider);
  padding: 28px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.scope-column-title {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.scope-column.is .scope-column-title {
  color: var(--accent);
}

.scope-column.is-not .scope-column-title {
  color: var(--text-muted);
}

.scope-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.scope-list li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.4;
}

.scope-list li::before {
  flex-shrink: 0;
  margin-top: 1px;
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.875rem;
  font-weight: 600;
}

.scope-column.is .scope-list li::before {
  content: "✓";
  color: var(--accent);
}

.scope-column.is-not .scope-list li::before {
  content: "—";
  color: var(--text-muted);
}

/* --- Privacy & Ownership ------------------------------------ */
.privacy-section {
  text-align: center;
}

.privacy-section .container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 40px;
}

.privacy-header {
  display: flex;
  flex-direction: column;
  gap: 12px;
  align-items: center;
}

.privacy-header h2 {
  max-width: 22ch;
}

.privacy-statements {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  width: 100%;
}

.privacy-statement {
  background-color: var(--surface);
  border-radius: var(--radius);
  border: 1px solid var(--divider);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  text-align: left;
}

.privacy-statement h3 {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
}

.privacy-statement p {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  max-width: none;
}

/* --- FAQ ---------------------------------------------------- */
.faq .container {
  display: flex;
  flex-direction: column;
  gap: 40px;
}

.faq-header {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 0;
  border-top: 1px solid var(--divider);
}

details.faq-item {
  border-bottom: 1px solid var(--divider);
}

details.faq-item summary {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-primary);
  padding: 20px 0;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  min-height: 44px;
}

details.faq-item summary::-webkit-details-marker {
  display: none;
}

details.faq-item summary::after {
  content: "+";
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 1.25rem;
  font-weight: 400;
  color: var(--text-muted);
  flex-shrink: 0;
  transition: transform 0.15s ease;
}

details.faq-item[open] summary::after {
  content: "−";
}

.faq-answer {
  font-size: 1rem;
  color: var(--text-secondary);
  padding-bottom: 20px;
  max-width: 60ch;
}

/* --- Footer -------------------------------------------------- */
.site-footer {
  border-top: 1px solid var(--divider);
  padding-block: 48px;
}

.site-footer .container {
  display: flex;
  flex-direction: column;
  gap: 24px;
  align-items: center;
  text-align: center;
}

.footer-links {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
  justify-content: center;
}

.footer-links a {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.footer-links a:hover {
  color: var(--text-primary);
  text-decoration: none;
}

.footer-copyright {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.8125rem;
  color: var(--text-muted);
  max-width: none;
}

/* --- Simple Pages (privacy, support) ------------------------ */
.simple-page {
  padding-block: 80px;
}

.simple-page .container {
  display: flex;
  flex-direction: column;
  gap: 40px;
  max-width: 640px;
}

.simple-page h1 {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
}

.simple-page .page-intro {
  font-size: 1.0625rem;
  color: var(--text-secondary);
  max-width: none;
}

.simple-page h2 {
  font-size: 1.25rem;
  margin-bottom: 8px;
}

.prose {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.prose-section {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.prose-section p {
  max-width: none;
}

.prose-section ul {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding-left: 20px;
}

.prose-section ul li {
  list-style: disc;
  color: var(--text-secondary);
  font-size: 1rem;
}

.back-link {
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 0.875rem;
  color: var(--text-secondary);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.back-link:hover {
  color: var(--text-primary);
  text-decoration: none;
}

/* --- Responsive --------------------------------------------- */
@media (max-width: 768px) {
  section {
    padding-block: 56px;
  }

  .hero {
    padding-block: 64px 56px;
  }

  .hero .container {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .hero-visual {
    order: -1;
  }

  .mascot-placeholder {
    width: 160px;
    height: 200px;
  }

  .steps {
    grid-template-columns: 1fr 1fr;
  }

  .screenshots {
    grid-template-columns: 1fr 1fr;
  }

  .screenshots .screenshot-frame:last-child {
    display: none;
  }

  .scope-columns {
    grid-template-columns: 1fr;
  }

  .privacy-statements {
    grid-template-columns: 1fr;
  }

  .nav-links {
    gap: 20px;
  }
}

@media (max-width: 480px) {
  body {
    font-size: 1rem;
  }

  .hero .container {
    gap: 32px;
  }

  .steps {
    grid-template-columns: 1fr;
  }

  .screenshots {
    grid-template-columns: 1fr;
    max-width: 240px;
    margin-inline: auto;
  }

  .screenshots .screenshot-frame:nth-child(n+2) {
    display: none;
  }

  .nav-links .btn {
    display: none;
  }
}