/* ============================================================
   CPO Study Hub — Stylesheet
   Aesthetic: refined aquatic, deep water + warm coral accent
   Display: Fraunces (serif w/ optical sizing)
   Body:    Manrope (modern geometric sans)
   ============================================================ */

/* ============================================
   AD CONTAINERS (Google AdSense)
   ============================================ */
.ad-section {
  padding: 32px 0 8px;
}
.ad-container {
  max-width: 970px;
  margin: 0 auto;
  padding: 14px 18px 18px;
  background: rgba(255, 255, 255, 0.55);
  border: 1px solid rgba(15, 58, 82, 0.08);
  border-radius: 12px;
  text-align: center;
  min-height: 120px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}
.ad-container .ad-label {
  font-family: var(--font-sans, 'Manrope', sans-serif);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: rgba(15, 58, 82, 0.5);
  margin-bottom: 10px;
  display: block;
}
.ad-container ins.adsbygoogle {
  display: block;
  width: 100%;
  min-height: 90px;
}
/* Ad container on dark backgrounds (e.g. inside dark sections) */
.ad-container.on-dark {
  background: rgba(255, 255, 255, 0.04);
  border-color: rgba(255, 255, 255, 0.08);
}
.ad-container.on-dark .ad-label {
  color: rgba(255, 255, 255, 0.5);
}
@media (max-width: 540px) {
  .ad-container {
    padding: 12px 12px 14px;
    min-height: 100px;
  }
}

:root {
  /* Core palette */
  --ink:        #0a1f2e;     /* deep ocean — primary text */
  --abyss:      #061521;     /* darker navy — backgrounds */
  --tide:       #0f3a52;     /* mid-depth blue */
  --shoal:      #2d6e87;     /* surface teal */
  --reef:       #4ec5d4;     /* bright aqua accent */
  --foam:       #e8f4f5;     /* pale blue-green */
  --shell:      #faf6ef;     /* warm off-white background */
  --sand:       #ede4d3;     /* warm tan */
  --coral:      #ff6b4a;     /* accent — buttons, highlights */
  --coral-dim:  #e85a3a;
  --citrine:    #f4b942;     /* secondary accent */

  /* Semantic */
  --correct:    #2a9d6e;
  --correct-bg: #e3f5ec;
  --wrong:      #d64545;
  --wrong-bg:   #fbe6e6;

  /* Typography */
  --display: "Fraunces", "Cormorant Garamond", Georgia, serif;
  --body:    "Manrope", "DM Sans", -apple-system, sans-serif;

  /* Layout */
  --max:        1180px;
  --radius-sm:  6px;
  --radius:     14px;
  --radius-lg:  22px;
  --shadow-sm:  0 1px 2px rgba(10,31,46,.06), 0 2px 8px rgba(10,31,46,.04);
  --shadow:     0 4px 16px rgba(10,31,46,.08), 0 12px 32px rgba(10,31,46,.06);
  --shadow-lg:  0 12px 40px rgba(10,31,46,.14), 0 24px 60px rgba(10,31,46,.08);
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--body);
  background: var(--shell);
  color: var(--ink);
  font-size: 17px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  font-feature-settings: "ss01", "cv11";
  overflow-x: hidden;
}

/* Soft animated background pattern */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(1200px 600px at 110% -10%, rgba(78,197,212,.10), transparent 60%),
    radial-gradient(900px 500px at -10% 110%, rgba(255,107,74,.06), transparent 60%),
    radial-gradient(700px 400px at 50% 50%, rgba(45,110,135,.04), transparent 70%);
  pointer-events: none;
}

/* ---- Typography ---- */
h1, h2, h3, h4 {
  font-family: var(--display);
  font-weight: 500;
  letter-spacing: -0.02em;
  color: var(--ink);
  line-height: 1.1;
}

h1 { font-size: clamp(2.4rem, 5.5vw, 4.6rem); font-weight: 400; }
h2 { font-size: clamp(1.8rem, 3.5vw, 2.8rem); font-weight: 400; }
h3 { font-size: 1.4rem; font-weight: 500; }

p { color: var(--tide); }

a {
  color: var(--shoal);
  text-decoration: none;
  transition: color .2s ease;
}
a:hover { color: var(--coral); }

/* ---- Layout containers ---- */
.container {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 28px;
}

/* ============================================================
   NAVIGATION
   ============================================================ */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(250,246,239,.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(10,31,46,.08);
}

.nav-inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 18px 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.logo {
  font-family: var(--display);
  font-size: 1.5rem;
  font-weight: 500;
  color: var(--ink);
  display: flex;
  align-items: center;
  gap: 10px;
  letter-spacing: -0.02em;
}

.logo-mark {
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, var(--tide), var(--reef));
  border-radius: 50%;
  position: relative;
  overflow: hidden;
  box-shadow: inset 0 -8px 12px rgba(10,31,46,.3), 0 2px 8px rgba(10,31,46,.15);
}
.logo-mark::before {
  content: "";
  position: absolute;
  top: 30%;
  left: -10%;
  right: -10%;
  height: 20%;
  background: rgba(232,244,245,.45);
  border-radius: 50%;
  filter: blur(1px);
}

.nav-links {
  display: flex;
  gap: 8px;
  list-style: none;
  align-items: center;
}

.nav-links a {
  padding: 10px 18px;
  border-radius: 100px;
  color: var(--tide);
  font-weight: 500;
  font-size: 0.95rem;
  transition: all .25s ease;
}
.nav-links a:hover {
  background: rgba(15,58,82,.08);
  color: var(--ink);
}
.nav-links a.active {
  background: var(--ink);
  color: var(--shell);
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 26px;
  border-radius: 100px;
  font-family: var(--body);
  font-size: 1rem;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all .25s cubic-bezier(.2,.8,.2,1);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.btn-primary {
  background: var(--ink);
  color: var(--shell);
  box-shadow: 0 4px 16px rgba(10,31,46,.2);
}
.btn-primary:hover {
  background: var(--coral);
  color: white;
  transform: translateY(-1px);
  box-shadow: 0 6px 24px rgba(255,107,74,.4);
}

.btn-secondary {
  background: transparent;
  color: var(--ink);
  border: 1.5px solid var(--ink);
}
.btn-secondary:hover {
  background: var(--ink);
  color: var(--shell);
}

.btn-ghost {
  background: transparent;
  color: var(--tide);
  padding: 10px 16px;
}
.btn-ghost:hover {
  background: rgba(15,58,82,.08);
  color: var(--ink);
}

.btn:disabled {
  opacity: .35;
  cursor: not-allowed;
  transform: none !important;
}

/* ============================================================
   HERO (home)
   ============================================================ */
.hero {
  padding: 90px 0 80px;
  position: relative;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 80px;
  align-items: center;
}

.eyebrow {
  display: inline-block;
  padding: 6px 14px;
  background: var(--foam);
  color: var(--tide);
  border-radius: 100px;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 24px;
}

.hero h1 {
  margin-bottom: 24px;
}
.hero h1 em {
  font-style: italic;
  color: var(--shoal);
  font-feature-settings: "ss01";
}

.hero-lede {
  font-size: 1.18rem;
  color: var(--tide);
  margin-bottom: 36px;
  max-width: 540px;
  line-height: 1.55;
}

.hero-cta { display: flex; gap: 14px; flex-wrap: wrap; }

/* Hero visual */
.hero-visual {
  position: relative;
  aspect-ratio: 1 / 1;
  max-width: 460px;
  margin-left: auto;
}

.water-orb {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  background:
    radial-gradient(circle at 35% 30%, rgba(232,244,245,.6), transparent 35%),
    radial-gradient(circle at 50% 50%, var(--reef), var(--tide) 60%, var(--abyss));
  box-shadow:
    inset 0 -30px 60px rgba(6,21,33,.4),
    inset 0 30px 60px rgba(232,244,245,.15),
    0 30px 80px rgba(15,58,82,.3);
  overflow: hidden;
  animation: bob 6s ease-in-out infinite;
}

.water-orb::before, .water-orb::after {
  content: "";
  position: absolute;
  left: 50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, transparent 38%, rgba(232,244,245,.12) 39%, transparent 41%);
  transform: translateX(-50%);
  animation: ripple 4s linear infinite;
}
.water-orb::after { animation-delay: -2s; }

@keyframes bob {
  0%,100% { transform: translateY(0); }
  50%     { transform: translateY(-14px); }
}
@keyframes ripple {
  0%   { top: 100%; opacity: 0; }
  20%  { opacity: 1; }
  100% { top: -100%; opacity: 0; }
}

/* ============================================================
   FEATURE CARDS (home)
   ============================================================ */
.features {
  padding: 60px 0 100px;
}

.feature-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
}

.feature {
  background: white;
  border-radius: var(--radius-lg);
  padding: 44px 38px;
  box-shadow: var(--shadow);
  border: 1px solid rgba(10,31,46,.05);
  position: relative;
  overflow: hidden;
  transition: transform .3s cubic-bezier(.2,.8,.2,1), box-shadow .3s;
  text-decoration: none;
  color: inherit;
  display: flex;
  flex-direction: column;
  min-height: 320px;
}
.feature:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
}
.feature::after {
  content: "";
  position: absolute;
  top: 0; right: 0;
  width: 200px;
  height: 200px;
  background: radial-gradient(circle at top right, rgba(78,197,212,.15), transparent 60%);
  pointer-events: none;
}

.feature-icon {
  width: 64px;
  height: 64px;
  border-radius: 18px;
  background: var(--foam);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 24px;
  font-size: 1.8rem;
  color: var(--tide);
}
.feature.coral .feature-icon {
  background: rgba(255,107,74,.12);
  color: var(--coral-dim);
}

.feature h3 {
  font-family: var(--display);
  font-size: 1.9rem;
  font-weight: 500;
  margin-bottom: 12px;
}

.feature p {
  color: var(--tide);
  margin-bottom: 24px;
  flex-grow: 1;
}

.feature-arrow {
  font-family: var(--display);
  font-size: 1rem;
  font-weight: 500;
  color: var(--ink);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: gap .25s;
}
.feature:hover .feature-arrow { gap: 12px; color: var(--coral); }

/* ============================================================
   STATS STRIP
   ============================================================ */
.stats {
  background: var(--ink);
  color: var(--shell);
  padding: 60px 0;
  margin: 60px 0;
  position: relative;
  overflow: hidden;
}
.stats::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(800px 400px at 80% 50%, rgba(78,197,212,.18), transparent 70%),
    radial-gradient(600px 300px at 20% 100%, rgba(255,107,74,.10), transparent 70%);
}
.stats-grid {
  position: relative;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 30px;
  text-align: center;
}
.stat-number {
  font-family: var(--display);
  font-size: 3.4rem;
  font-weight: 400;
  color: var(--reef);
  line-height: 1;
  margin-bottom: 6px;
  font-feature-settings: "ss01";
}
.stat-label {
  color: rgba(232,244,245,.7);
  font-size: 0.9rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* ============================================================
   ABOUT SECTION
   ============================================================ */
.about {
  padding: 80px 0;
}
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  align-items: start;
}
.about-text p {
  font-size: 1.1rem;
  margin-bottom: 18px;
}
.about-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.about-list li {
  display: flex;
  gap: 18px;
  align-items: start;
  padding: 18px;
  background: white;
  border-radius: var(--radius);
  border: 1px solid rgba(10,31,46,.06);
}
.about-num {
  font-family: var(--display);
  font-size: 1.6rem;
  color: var(--coral);
  font-weight: 500;
  min-width: 32px;
  line-height: 1;
}
.about-list strong { color: var(--ink); display: block; margin-bottom: 4px; font-size: 1.05rem;}

/* ============================================================
   FOOTER
   ============================================================ */
.footer {
  background: var(--abyss);
  color: rgba(232,244,245,.6);
  padding: 50px 0 30px;
  margin-top: 80px;
  font-size: 0.9rem;
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
}
.footer a { color: var(--reef); }
.footer-disclaimer { max-width: 600px; line-height: 1.5; }

/* ============================================================
   PAGE HEADER (for sub-pages)
   ============================================================ */
.page-header {
  padding: 70px 0 40px;
}
.page-header .eyebrow { margin-bottom: 18px; }
.page-header h1 { margin-bottom: 16px; }
.page-header p { font-size: 1.1rem; max-width: 680px; }

/* ============================================================
   PRACTICE TEST
   ============================================================ */
.test-setup {
  background: white;
  border-radius: var(--radius-lg);
  padding: 48px 44px;
  box-shadow: var(--shadow);
  border: 1px solid rgba(10,31,46,.06);
  margin-bottom: 40px;
}

.setup-row {
  margin-bottom: 28px;
}
.setup-row:last-child { margin-bottom: 0; }
.setup-label {
  display: block;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--ink);
  font-size: 0.95rem;
  letter-spacing: 0.02em;
}

.choice-group {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
.choice-pill {
  padding: 10px 18px;
  border-radius: 100px;
  border: 1.5px solid rgba(10,31,46,.15);
  background: transparent;
  cursor: pointer;
  font-family: var(--body);
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--tide);
  transition: all .2s;
}
.choice-pill:hover { border-color: var(--ink); color: var(--ink); }
.choice-pill.selected {
  background: var(--ink);
  color: var(--shell);
  border-color: var(--ink);
}

/* Progress bar */
.progress-bar {
  height: 4px;
  background: rgba(10,31,46,.08);
  border-radius: 100px;
  overflow: hidden;
  margin-bottom: 24px;
}
.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--shoal), var(--reef));
  border-radius: 100px;
  transition: width .4s cubic-bezier(.2,.8,.2,1);
}

.q-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 30px;
  color: var(--tide);
  font-size: 0.9rem;
  font-weight: 500;
}
.q-topic {
  padding: 4px 12px;
  background: var(--foam);
  border-radius: 100px;
  color: var(--shoal);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

/* Question card */
.q-card {
  background: white;
  border-radius: var(--radius-lg);
  padding: 44px 44px 36px;
  box-shadow: var(--shadow);
  border: 1px solid rgba(10,31,46,.06);
}

.q-text {
  font-family: var(--display);
  font-size: 1.6rem;
  font-weight: 400;
  line-height: 1.35;
  color: var(--ink);
  margin-bottom: 30px;
  letter-spacing: -0.01em;
}

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

.option {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 18px 22px;
  background: var(--shell);
  border: 1.5px solid transparent;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all .2s cubic-bezier(.2,.8,.2,1);
  font-family: var(--body);
  font-size: 1rem;
  text-align: left;
  width: 100%;
  color: var(--ink);
  line-height: 1.4;
}
.option:hover:not(:disabled) {
  border-color: var(--shoal);
  background: white;
  transform: translateX(4px);
}
.option:disabled { cursor: default; }

.option-letter {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: white;
  border: 1.5px solid rgba(10,31,46,.15);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.88rem;
  color: var(--tide);
  flex-shrink: 0;
  transition: all .25s;
}
.option:hover:not(:disabled) .option-letter {
  border-color: var(--shoal);
  color: var(--shoal);
}

.option.correct {
  border-color: var(--correct);
  background: var(--correct-bg);
}
.option.correct .option-letter {
  background: var(--correct);
  color: white;
  border-color: var(--correct);
}

.option.wrong {
  border-color: var(--wrong);
  background: var(--wrong-bg);
}
.option.wrong .option-letter {
  background: var(--wrong);
  color: white;
  border-color: var(--wrong);
}

.option.reveal-correct {
  border-color: var(--correct);
}
.option.reveal-correct .option-letter {
  border-color: var(--correct);
  color: var(--correct);
}

.explanation {
  margin-top: 26px;
  padding: 22px 26px;
  background: var(--foam);
  border-radius: var(--radius);
  border-left: 3px solid var(--shoal);
  font-size: 0.98rem;
  color: var(--ink);
  line-height: 1.6;
  animation: slideIn .35s ease-out;
}
.explanation strong { color: var(--tide); display: block; margin-bottom: 4px; font-size: 0.78rem; letter-spacing: 0.08em; text-transform: uppercase;}

@keyframes slideIn {
  from { opacity: 0; transform: translateY(-6px); }
  to   { opacity: 1; transform: translateY(0); }
}

.q-actions {
  display: flex;
  justify-content: space-between;
  margin-top: 30px;
  gap: 12px;
}

/* Results screen */
.result-card {
  background: white;
  border-radius: var(--radius-lg);
  padding: 56px 44px;
  box-shadow: var(--shadow);
  border: 1px solid rgba(10,31,46,.06);
  text-align: center;
}

.score-circle {
  width: 200px;
  height: 200px;
  margin: 0 auto 30px;
  position: relative;
}
.score-percent {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  font-family: var(--display);
}
.score-percent .num {
  font-size: 3.6rem;
  font-weight: 500;
  color: var(--ink);
  line-height: 1;
}
.score-percent .lbl {
  font-size: 0.85rem;
  color: var(--tide);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-top: 4px;
  font-family: var(--body);
  font-weight: 600;
}

.score-msg {
  font-family: var(--display);
  font-size: 1.8rem;
  font-weight: 400;
  color: var(--ink);
  margin-bottom: 10px;
}
.score-detail { color: var(--tide); margin-bottom: 36px; }

.topic-breakdown {
  text-align: left;
  margin: 36px 0;
  display: grid;
  gap: 10px;
}
.topic-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 20px;
  background: var(--shell);
  border-radius: var(--radius);
  font-size: 0.95rem;
}
.topic-row .topic-name { font-weight: 600; color: var(--ink); }
.topic-row .topic-score { color: var(--tide); }

.result-actions {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ============================================================
   FLASHCARDS
   ============================================================ */
.fc-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 40px;
}

.fc-counter {
  font-family: var(--display);
  font-size: 1.1rem;
  color: var(--tide);
  font-weight: 500;
}
.fc-counter strong {
  font-weight: 500;
  color: var(--ink);
  font-size: 1.6rem;
}

.fc-stage {
  perspective: 1600px;
  margin: 0 auto;
  max-width: 740px;
}

.flashcard {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 10;
  transform-style: preserve-3d;
  transition: transform .7s cubic-bezier(.2,.8,.2,1);
  cursor: pointer;
}
.flashcard.flipped { transform: rotateY(180deg); }

.fc-face {
  position: absolute;
  inset: 0;
  border-radius: var(--radius-lg);
  padding: 56px 60px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  box-shadow: var(--shadow);
  overflow: hidden;
}

.fc-front {
  background: linear-gradient(135deg, white, var(--foam));
  border: 1px solid rgba(10,31,46,.06);
}
.fc-front::before {
  content: "";
  position: absolute;
  top: -50%;
  right: -30%;
  width: 80%;
  height: 80%;
  background: radial-gradient(circle, rgba(78,197,212,.18), transparent 60%);
}

.fc-back {
  background: var(--ink);
  color: var(--shell);
  transform: rotateY(180deg);
  border: 1px solid var(--abyss);
}
.fc-back::before {
  content: "";
  position: absolute;
  bottom: -50%;
  left: -20%;
  width: 70%;
  height: 70%;
  background: radial-gradient(circle, rgba(255,107,74,.15), transparent 60%);
}

.fc-category {
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  font-weight: 600;
  margin-bottom: 24px;
  position: relative;
  z-index: 1;
}
.fc-front .fc-category { color: var(--shoal); }
.fc-back  .fc-category { color: var(--reef); }

.fc-text {
  position: relative;
  z-index: 1;
  max-width: 90%;
}
.fc-front .fc-text {
  font-family: var(--display);
  font-size: clamp(1.6rem, 3vw, 2.4rem);
  font-weight: 400;
  color: var(--ink);
  line-height: 1.2;
  letter-spacing: -0.02em;
}
.fc-back .fc-text {
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  line-height: 1.55;
  color: rgba(232,244,245,.95);
}

.fc-hint {
  position: absolute;
  bottom: 20px;
  font-size: 0.78rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  opacity: 0.5;
  z-index: 1;
}
.fc-front .fc-hint { color: var(--tide); }
.fc-back  .fc-hint { color: var(--reef); }

.fc-nav {
  display: flex;
  justify-content: center;
  gap: 14px;
  margin-top: 36px;
  flex-wrap: wrap;
}

.fc-btn {
  width: 52px;
  height: 52px;
  border-radius: 50%;
  border: 1.5px solid rgba(10,31,46,.15);
  background: white;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  color: var(--ink);
  transition: all .25s;
}
.fc-btn:hover { background: var(--ink); color: var(--shell); border-color: var(--ink); }
.fc-btn:disabled { opacity: .3; cursor: not-allowed; }
.fc-btn:disabled:hover { background: white; color: var(--ink); border-color: rgba(10,31,46,.15); }

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 900px) {
  .hero-grid, .about-grid, .feature-grid { grid-template-columns: 1fr; gap: 40px; }
  .hero-visual { max-width: 320px; margin: 0 auto; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  h1 { font-size: 2.6rem; }
  .nav-links a { padding: 8px 12px; font-size: 0.9rem; }
  .q-card, .test-setup, .result-card { padding: 28px 24px; }
  .q-text { font-size: 1.3rem; }
  .fc-face { padding: 36px 30px; }
  .q-actions { flex-direction: column-reverse; }
  .q-actions .btn { width: 100%; justify-content: center; }
}

@media (max-width: 540px) {
  .container { padding: 0 18px; }
  .stat-number { font-size: 2.4rem; }
  .stats-grid { grid-template-columns: 1fr 1fr; }
  .logo { font-size: 1.2rem; }
  .nav-inner { padding: 14px 18px; }
  .hero { padding: 50px 0; }
  .feature { padding: 32px 26px; min-height: 0;}
}