:root {
  --bg: #fff;
  --fg: #000;
  --muted: #6b6b6b;
  --line: #e2e2e2;
  --soft: #f5f5f5;
  --primary-hover: #333;
  --radius: 14px;
  color-scheme: light;
}

/* Modo oscuro: sigue al sistema salvo que la persona elija "claro" con el botón. */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #000; --fg: #fff; --muted: #9a9a9a; --line: #2c2c2c; --soft: #141414; --primary-hover: #ddd;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #000; --fg: #fff; --muted: #9a9a9a; --line: #2c2c2c; --soft: #141414; --primary-hover: #ddd;
  color-scheme: dark;
}

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

html { font-size: clamp(17px, 1.1vw + 13px, 20px); }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--fg);
  min-height: 100vh;
  min-height: 100dvh;
  line-height: 1.45;
  -webkit-font-smoothing: antialiased;
  transition: background .2s, color .2s;
}

#app {
  max-width: 880px;
  margin: 0 auto;
  padding: clamp(28px, 6vw, 72px) 16px;
}

.screen { display: none; flex-direction: column; gap: 1.5rem; }
.screen.active { display: flex; animation: fade .25s ease; }
@keyframes fade { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; } }

h1 { font-size: clamp(2.2rem, 6vw, 3.4rem); font-weight: 700; letter-spacing: -0.03em; line-height: 1.1; }
.eyebrow { font-size: .85rem; text-transform: uppercase; letter-spacing: .14em; color: var(--muted); }
.lead { font-size: 1.15rem; }
.muted { color: var(--muted); }
.hidden { display: none !important; }
.row { display: flex; gap: 12px; flex-wrap: wrap; }

/* Botones */
.btn {
  font: inherit;
  font-size: 1.05rem;
  font-weight: 600;
  padding: .85em 1.5em;
  border-radius: var(--radius);
  border: 1.5px solid var(--fg);
  background: var(--bg);
  color: var(--fg);
  cursor: pointer;
  transition: transform .1s, background .15s, color .15s;
}
.btn:hover { background: var(--soft); }
.btn:active { transform: scale(.97); }
.btn-primary { background: var(--fg); color: var(--bg); }
.btn-primary:hover { background: var(--primary-hover); }
.btn-danger { border-color: var(--line); color: var(--muted); }
.btn-link {
  border: none; background: none; padding: 0;
  color: var(--muted); align-self: flex-start; font-weight: 500;
  text-decoration: underline; text-underline-offset: 4px;
}
.btn-link:hover { background: none; color: var(--fg); }
.btn:focus-visible, .answer:focus-visible { outline: 2px solid var(--fg); outline-offset: 3px; }

/* Inicio */
#screen-start { min-height: 70vh; justify-content: center; }
.start-form { display: flex; gap: 12px; flex-wrap: wrap; }
.start-form input {
  flex: 1 1 260px;
  font: inherit;
  font-size: 1.2rem;
  padding: .8em 1em;
  border: 1.5px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg);
  color: var(--fg);
  outline: none;
  transition: border-color .15s;
}
.start-form input:focus { border-color: var(--fg); }

/* Pregunta */
.quiz-top { display: flex; justify-content: space-between; align-items: center; font-size: 1rem; }
#q-counter { font-weight: 600; color: var(--fg); }
.progress { height: 4px; background: var(--line); border-radius: 99px; overflow: hidden; }
.progress-bar { height: 100%; width: 0; background: var(--fg); transition: width .3s ease; }
.question {
  font-size: clamp(1.5rem, 4vw, 2.2rem);
  font-weight: 650;
  letter-spacing: -0.015em;
  line-height: 1.25;
  padding: 1rem 0;
}

.answers { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.answer {
  font: inherit;
  font-size: 1.15rem;
  font-weight: 500;
  color: var(--fg);
  background: var(--bg);
  border: 1.5px solid var(--line);
  border-radius: var(--radius);
  padding: 1.1em 1.2em;
  min-height: 6rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  text-align: left;
  cursor: pointer;
  transition: border-color .15s, background .15s, opacity .2s, transform .1s;
}
.answer:hover:not(:disabled) { border-color: var(--fg); }
.answer:active:not(:disabled) { transform: scale(.98); }
.answer:disabled { cursor: default; }
.answer .letter {
  flex: 0 0 auto;
  width: 2.2em; height: 2.2em;
  display: grid; place-items: center;
  border: 1.5px solid currentColor;
  border-radius: 50%;
  font-weight: 700;
  font-size: .9em;
}
.answer.correct { background: var(--fg); color: var(--bg); border-color: var(--fg); }
.answer.wrong { border-color: var(--fg); border-style: dashed; }
.answer.wrong span:last-child { text-decoration: line-through; }
.answer.dim { opacity: .3; }

.feedback { display: flex; align-items: center; justify-content: space-between; gap: 1rem; flex-wrap: wrap; padding-top: .5rem; }
.feedback p { font-size: 1.5rem; font-weight: 700; }

/* Final */
.stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.stats > div {
  border: 1.5px solid var(--line);
  border-radius: var(--radius);
  padding: 1.4rem;
  display: flex; flex-direction: column; gap: .25rem;
}
.stat-num { font-size: clamp(2rem, 5vw, 2.8rem); font-weight: 700; letter-spacing: -0.02em; }

@media (max-width: 640px) {
  .answers { grid-template-columns: 1fr; gap: 10px; }
  .answer { min-height: 4.2rem; padding: .9em 1em; }
  .stats { grid-template-columns: 1fr; }
  .feedback { flex-direction: column; align-items: stretch; text-align: center; }
  .feedback .btn, .start-form .btn, .row .btn { width: 100%; }
}


.sent-ok {
  font-size: 1.25rem;
  font-weight: 600;
  padding: 1rem 1.2rem;
  border: 1.5px solid var(--fg);
  border-radius: var(--radius);
}

/* Botón de tema */
.theme-toggle {
  position: fixed;
  top: 16px;
  right: 16px;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border: 1.5px solid var(--muted);
  border-radius: 50%;
  background: var(--bg);
  color: var(--fg);
  cursor: pointer;
  z-index: 10;
  transition: border-color .15s, background .2s;
}
.theme-toggle:hover { border-color: var(--fg); }
.theme-toggle:focus-visible { outline: 2px solid var(--fg); outline-offset: 3px; }
.theme-toggle svg { width: 20px; height: 20px; }
.theme-toggle .icon-sun { display: none; }
.theme-toggle.is-dark .icon-sun { display: block; }
.theme-toggle.is-dark .icon-moon { display: none; }
#app { padding-top: max(76px, clamp(28px, 6vw, 72px)); }