:root {
  --site-max-width: 1200px;
  --space-xxs: 4px;
  --space-xs: 8px;
  --space-s: 16px;
  --space-m: 24px;
  --space-l: 32px;
  --space-xl: 48px;
  --pink: #ffe4ec;
  --pink-deep: #ffd0de;
  --ink: #000000;
  --ink-soft: #2a2a2a;
  --muted: #4a4a4a;
  --navbar-h: 64px;
  --blob-size: 280px;

  /* Q&A / body — same on mobile and desktop */
  --question-size: 26px;
  --question-weight: 800;
  --body-size: 18px;
  --body-weight: 400;
  --body-line: 1.7;

  /* Matches "phd level ai chat" */
  --tagline-weight: 500;
}

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

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

html,
body {
  width: 100%;
  margin: 0;
  padding: 0;
}

body {
  min-height: 100vh;
  overflow-x: hidden;
  background: var(--pink);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-tap-highlight-color: transparent;
}

body.menu-open {
  overflow: hidden;
}

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

/* ========== HAMBURGER (fixed, always on top of overlay) ========== */

.hamburger {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 6px;
  width: 48px;
  height: 48px;
  padding: 0;
  border: none;
  background: transparent;
  cursor: pointer;
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 1100;
  -webkit-tap-highlight-color: transparent;
}

.hamburger-line {
  display: block;
  width: 24px;
  height: 2.5px;
  background: #000;
  border-radius: 2px;
  transition:
    transform 0.3s cubic-bezier(0.4, 0, 0.2, 1),
    opacity 0.2s ease;
  transform-origin: center;
  flex-shrink: 0;
}

.hamburger.is-open .hamburger-line:nth-child(1) {
  transform: translateY(8.5px) rotate(45deg);
}

.hamburger.is-open .hamburger-line:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}

.hamburger.is-open .hamburger-line:nth-child(3) {
  transform: translateY(-8.5px) rotate(-45deg);
}

/* ========== NAVBAR ========== */

.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--navbar-h);
  padding: 0 var(--space-m);
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent; /* see content behind */
  pointer-events: none;
}

.navbar .nav-brand,
.navbar .nav-links-desktop {
  pointer-events: auto;
}

.nav-brand {
  font-size: 26px;
  font-weight: 800;
  color: #000;
  letter-spacing: -0.03em;
  line-height: 1;
}

/* Desktop: stacked fixed links, top left */
.nav-links-desktop {
  display: none;
  flex-direction: column;
  align-items: flex-start;
  gap: 12px;
  position: fixed;
  top: 24px;
  left: 28px;
  z-index: 1000;
}

.nav-links-desktop a {
  font-size: 18px;
  font-weight: var(--tagline-weight); /* same as phd level ai chat */
  color: #000;
  letter-spacing: 0.02em;
  line-height: 1.2;
  transition: opacity 0.2s;
}

.nav-links-desktop a:hover {
  opacity: 0.55;
}

/* ========== MOBILE MENU OVERLAY ========== */

.mobile-menu {
  position: fixed;
  inset: 0;
  z-index: 1050;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--pink);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.35s ease, visibility 0.35s ease;
}

.mobile-menu.is-open {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

.mobile-menu[hidden] {
  display: flex;
}

.mobile-menu-links {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: clamp(28px, 8vh, 56px);
  text-align: center;
}

.mobile-menu-links a {
  font-size: clamp(28px, 7vw, 40px);
  font-weight: var(--tagline-weight); /* same as phd level ai chat */
  color: #000;
  letter-spacing: -0.02em;
  opacity: 0;
  transform: translateY(16px);
  transition:
    opacity 0.35s ease,
    transform 0.35s ease;
}

.mobile-menu.is-open .mobile-menu-links a {
  opacity: 1;
  transform: translateY(0);
}

.mobile-menu.is-open .mobile-menu-links a:nth-child(1) { transition-delay: 0.05s; }
.mobile-menu.is-open .mobile-menu-links a:nth-child(2) { transition-delay: 0.1s; }
.mobile-menu.is-open .mobile-menu-links a:nth-child(3) { transition-delay: 0.15s; }
.mobile-menu.is-open .mobile-menu-links a:nth-child(4) { transition-delay: 0.2s; }

.mobile-menu-links a:active {
  opacity: 0.55;
}

/* ========== HERO ========== */

.hero {
  min-height: 100vh;
  min-height: 100svh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: calc(var(--navbar-h) + var(--space-l)) var(--space-m) var(--space-xl);
  background: var(--pink);
}

.hero-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: var(--space-m);
}

.profile-logo {
  width: var(--blob-size);
  height: var(--blob-size);
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  flex-shrink: 0;
}

.profile-logo canvas {
  width: 100%;
  height: 100%;
  display: block;
}

.hero-tagline {
  margin: 0;
  font-size: 18px;
  font-weight: var(--tagline-weight);
  color: var(--ink-soft);
  letter-spacing: 0.02em;
}

/* Mobile-only rectangle sign up button */
.signup-btn-mobile {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-top: var(--space-s);
  min-width: 200px;
  padding: 14px 40px;
  border: 1.5px solid #000;
  border-radius: 6px;
  background: transparent;
  color: #000;
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: lowercase;
  cursor: pointer;
  transition: background 0.25s, color 0.25s, transform 0.2s;
}

.signup-btn-mobile:hover {
  background: #000;
  color: #fff;
  transform: translateY(-1px);
}

/* ========== Q&A — same size/weight mobile + desktop ========== */

.qa-section {
  display: flex;
  align-items: flex-start;
  padding: var(--space-xl) var(--space-m);
  background: var(--pink);
}

.qa-section:first-of-type {
  padding-top: var(--space-l);
}

.qa-inner {
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
  text-align: left;
}

.question {
  margin: 0 0 var(--space-m);
  font-size: var(--question-size);
  font-weight: var(--question-weight);
  color: #000;
  letter-spacing: -0.03em;
  line-height: 1.2;
  text-align: left;
}

.qa-inner p {
  margin: 0 0 var(--space-m);
  color: var(--muted);
  font-size: var(--body-size);
  font-weight: var(--body-weight);
  line-height: var(--body-line);
  word-spacing: 0.04em;
  letter-spacing: 0.15px;
  text-align: left;
}

.qa-inner p:last-of-type {
  margin-bottom: var(--space-l);
}

.footer-button {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  gap: 8px;
  margin-top: var(--space-m);
  margin-bottom: var(--space-m);
  padding: 12px 26px;
  border: 1.5px solid rgba(0, 0, 0, 0.35);
  border-radius: 40px;
  background: transparent;
  color: #000;
  font-size: 15px;
  font-weight: 500;
  text-align: center;
  cursor: pointer;
  transition: background 0.25s, transform 0.25s, box-shadow 0.25s;
}

.footer-button:hover {
  background: rgba(0, 0, 0, 0.06);
  transform: translateY(-2px);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.08);
}

.tos-link {
  display: block;
  margin-top: var(--space-s);
  margin-bottom: var(--space-xl);
  color: var(--muted);
  font-size: 14px;
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ========== DESKTOP ========== */

@media (min-width: 900px) {
  .hamburger {
    display: none;
  }

  .nav-links-desktop {
    display: flex;
  }

  .nav-brand {
    font-size: 32px;
    font-weight: 800;
  }

  .nav-links-desktop a {
    font-size: 18px;
    font-weight: var(--tagline-weight); /* same as phd level ai chat */
  }

  .signup-btn-mobile {
    display: none;
  }

  .profile-logo {
    width: var(--blob-size);
    height: var(--blob-size);
  }

  .question {
    font-size: var(--question-size);
    font-weight: var(--question-weight);
  }

  .qa-inner p {
    font-size: var(--body-size);
    font-weight: var(--body-weight);
    line-height: var(--body-line);
  }

  .hero-tagline {
    font-size: 18px;
    font-weight: var(--tagline-weight);
  }

  .qa-section {
    padding: var(--space-xl) var(--space-m);
  }

  .qa-inner {
    max-width: 780px;
    margin-left: max(160px, calc((100% - var(--site-max-width)) / 2 + var(--space-m)));
    margin-right: auto;
  }
}

/* Reduce motion */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .hamburger-line,
  .mobile-menu,
  .mobile-menu-links a,
  .signup-btn-mobile,
  .footer-button {
    transition: none;
  }
}