/* =========================================================
   Presente (Voseo) — estilos base
   Paleta: blanco / negro / azul (#0092ff)
   ========================================================= */

:root {
  --color-bg: #ffffff;
  --color-fg: #0a0a0a;
  --color-muted: #6b7280;
  --color-border: #e5e7eb;
  --color-accent: #0092ff;
  --color-accent-hover: #0080e0;
  --color-success: #12a150;
  --color-error: #e0393e;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;

  --space-1: 0.5rem;
  --space-2: 1rem;
  --space-3: 1.5rem;
  --space-4: 2.5rem;
  --space-5: 4rem;

  --max-width: 640px;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Helvetica, Arial, sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-fg);
  font-family: var(--font-sans);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3 {
  font-weight: 600;
  letter-spacing: -0.02em;
  margin: 0;
}

h1 {
  font-size: clamp(1.75rem, 4vw + 1rem, 2.75rem);
}

h2 {
  font-size: clamp(1.4rem, 2.5vw + 1rem, 1.9rem);
}

h3 {
  font-size: 1rem;
  color: var(--color-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

p {
  margin: 0;
}

a {
  color: var(--color-accent);
  font-weight: 600;
}

a:hover {
  color: var(--color-accent-hover);
}

button {
  font-family: inherit;
}

/* =========================================================
   Layout
   ========================================================= */

#app {
  min-height: 100vh;
}

.screen {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-4) var(--space-2);
}

.hidden {
  display: none !important;
}

.screen-content {
  width: 100%;
  max-width: var(--max-width);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

/* =========================================================
   Botones
   ========================================================= */

.btn {
  appearance: none;
  border: none;
  border-radius: var(--radius-sm);
  padding: 0.85rem 1.5rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease,
    color 0.15s ease, opacity 0.15s ease;
}

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

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

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

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

.btn-secondary:hover {
  background: var(--color-fg);
  color: #ffffff;
}

.btn-large {
  padding: 1.1rem 2.5rem;
  font-size: 1.1rem;
  align-self: flex-start;
}

.btn-back {
  appearance: none;
  border: none;
  background: none;
  color: var(--color-muted);
  font-size: 0.9rem;
  cursor: pointer;
  padding: 0;
  align-self: flex-start;
}

.btn-back:hover {
  color: var(--color-fg);
}

/* =========================================================
   Pantalla: Inicio
   ========================================================= */

.home-content {
  text-align: center;
  align-items: center;
  gap: var(--space-5);
}

.home-content .level-grid {
  width: 100%;
}

.home-content .level-card {
  align-items: center;
  text-align: center;
}

.home-content .btn-large {
  align-self: center;
}

.level-card-icon {
  font-size: 1.1rem;
  line-height: 1;
}

/* =========================================================
   Tarjetas de nivel (pantalla de inicio)
   ========================================================= */

.level-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-2);
}

.level-card {
  appearance: none;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: var(--space-1);
  background: var(--color-bg);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-3) var(--space-2);
  cursor: pointer;
  text-align: left;
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.level-card:hover:not(:disabled) {
  border-color: var(--color-accent);
  transform: translateY(-2px);
}

.level-card:disabled,
.level-card.is-locked {
  cursor: not-allowed;
  opacity: 0.5;
  pointer-events: none;
}

.level-card-title {
  font-weight: 600;
  font-size: 1.05rem;
}

/* =========================================================
   Pantalla: Ejercicio
   ========================================================= */

.exercise-content {
  gap: var(--space-2);
}

.exercise-meta {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-size: 0.9rem;
  color: var(--color-muted);
}

.progress-bar {
  width: 100%;
  height: 8px;
  background: var(--color-border);
  border-radius: 999px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: var(--color-accent);
  border-radius: 999px;
  transition: width 0.2s ease;
}

.exercise-sentence {
  font-size: clamp(1.15rem, 2vw + 0.8rem, 1.5rem);
  line-height: 1.6;
  margin-top: var(--space-2);
}

.answer-input-inline {
  font: inherit;
  font-weight: 600;
  color: var(--color-accent);
  text-align: center;
  background: transparent;
  border: none;
  border-bottom: 2px solid var(--color-accent);
  width: 6ch;
  min-width: 6ch;
  max-width: 14ch;
  padding: 0 0.15em;
  margin: 0 0.1em;
  transition: width 0.1s ease;
}

.answer-input-inline:focus {
  outline: none;
  border-bottom-color: var(--color-accent-hover);
}

.answer-input-inline.is-correct {
  border-bottom-color: var(--color-success);
  color: var(--color-success);
}

.answer-input-inline.is-incorrect {
  border-bottom-color: var(--color-error);
  color: var(--color-error);
}

.answer-row {
  display: flex;
  justify-content: flex-end;
  margin-top: var(--space-1);
}

/* Lugares reservados: mensaje de feedback, explicación, botón siguiente */
.placeholder-box {
  min-height: 3rem;
  border: 1.5px dashed var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-2);
  font-size: 0.9rem;
  color: var(--color-muted);
}

.feedback-message,
.explanation-box {
  display: flex;
  align-items: center;
}

.feedback-message.is-success {
  border-style: solid;
  border-color: var(--color-success);
  color: var(--color-success);
}

.feedback-message.is-error {
  border-style: solid;
  border-color: var(--color-error);
  color: var(--color-error);
}

/* =========================================================
   Pantalla: Final
   ========================================================= */

.summary-content {
  gap: var(--space-3);
}

.score {
  font-size: 1.2rem;
}

.score strong {
  color: var(--color-accent);
}

.error-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.error-list ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.error-item {
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-2);
}

.error-sentence {
  margin-bottom: 0.35rem;
}

.error-answer {
  font-size: 0.9rem;
  color: var(--color-muted);
}

.is-wrong {
  color: var(--color-error);
  text-decoration: line-through;
}

.is-correct {
  color: var(--color-success);
  font-weight: 600;
}

.summary-actions {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.summary-actions .btn {
  flex: 1;
  min-width: 200px;
}

/* =========================================================
   Responsive
   ========================================================= */

@media (max-width: 560px) {
  .level-grid {
    grid-template-columns: 1fr;
  }

  .answer-row {
    flex-direction: column;
  }

  .btn-large {
    width: 100%;
  }

  .summary-actions {
    flex-direction: column;
  }

  .summary-actions .btn {
    min-width: 0;
  }
}