/* --- Variables Globales y Reset --- */
:root {
    --font-main: 'Inter', sans-serif;
    --color-bg: #f4f7f6;
    --color-text: #333;
    --color-text-light: #555;
    --color-card-bg: #ffffff;
    --color-border: #e0e0e0;
    --color-primary: #007aff;
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
    --border-radius: 12px;

    /* Degradados para los 10 capítulos  */
    --grad-1: linear-gradient(135deg, #5f72be, #9921e8); /* Llegada */
    --grad-2: linear-gradient(135deg, #ff6a00, #ee0979); /* Alojamiento */
    --grad-3: linear-gradient(135deg, #02aab0, #00cdac); /* Comidas */
    --grad-4: linear-gradient(135deg, #d38312, #a83279); /* Compras */
    --grad-5: linear-gradient(135deg, #11998e, #38ef7d); /* Orientación */
    --grad-6: linear-gradient(135deg, #c6426e, #642b73); /* Turismo */
    --grad-7: linear-gradient(135deg, #00c6ff, #0072ff); /* Conversación */
    --grad-8: linear-gradient(135deg, #e53935, #e35d5b); /* Emergencias */
    --grad-9: linear-gradient(135deg, #ff8c00, #ffc837); /* Clima */
    --grad-10: linear-gradient(135deg, #47cacc, #5773cf); /* Comunicación */
}

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

body {
    font-family: var(--font-main);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
}

/* --- Estructura de la App (Mobile-First)  --- */
.app-container {
    max-width: 600px;
    margin: 0 auto;
    background-color: var(--color-card-bg);
    min-height: 100vh;
}

.screen {
    display: none; /* Ocultamos todas las pantallas por defecto */
    flex-direction: column;
    min-height: 100vh;
}

.screen.active {
    display: flex; /* Mostramos solo la activa */
}

.app-header {
    padding: 20px;
    background-color: var(--color-card-bg);
}

.app-header.sticky {
    position: sticky;
    top: 0;
    z-index: 10;
    box-shadow: var(--shadow-sm);
    display: flex;
    align-items: center;
}

.app-header h1, .app-header h2 {
    margin-bottom: 4px;
}
.app-header h2 {
    margin-left: 16px;
}

.back-btn {
    background: none;
    border: 2px solid var(--color-border);
    font-size: 16px;
    font-weight: 600;
    padding: 8px 12px;
    border-radius: 8px;
    cursor: pointer;
}

main {
    padding: 20px;
    flex-grow: 1;
}

footer {
    padding: 20px;
    text-align: center;
}

button {
    font-family: var(--font-main);
    font-size: 16px;
    cursor: pointer;
    border: none;
    border-radius: 8px;
    padding: 12px 20px;
}

/* --- Pantalla de Inicio (Capítulos) --- */
.chapter-grid {
    display: grid;
    grid-template-columns: 1fr; /* 1 columna en móvil */
    gap: 16px;
}

.chapter-card {
    position: relative;
    color: white;
    padding: 20px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    cursor: pointer;
    transition: transform 0.2s ease;
    overflow: hidden;
}

.chapter-card:hover {
    transform: translateY(-5px);
}

.chapter-card h3 {
    font-size: 24px;
    margin-bottom: 8px;
    position: relative;
    z-index: 2;
}

.chapter-card p {
    font-size: 14px;
    position: relative;
    z-index: 2;
    opacity: 0.9;
}

.chapter-card .progress-bar {
    position: absolute;
    bottom: 0;
    left: 0;
    height: 8px;
    background-color: rgba(255, 255, 255, 0.4);
    width: 100%;
    z-index: 1;
}

.chapter-card .progress-bar-inner {
    height: 100%;
    width: 0; /* Se actualizará con JS */
    background-color: #ffffff;
    transition: width 0.5s ease;
}

/* --- Pantalla de Temas --- */
.topic-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.topic-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background-color: var(--color-bg);
    padding: 16px;
    border-radius: var(--border-radius);
    border: 1px solid var(--color-border);
    cursor: pointer;
}

.topic-item.completed {
    background-color: #e5fbe5;
    border-color: #5cb85c;
}

.topic-item span {
    font-weight: 600;
}

.topic-item .status-icon {
    font-size: 20px;
}

/* --- Pantalla de Lección --- */
.phrases-container {
    margin-top: 16px;
}

.phrase-pair {
    display: grid;
    grid-template-columns: 1fr auto;
    align-items: center;
    gap: 10px;
    background: var(--color-bg);
    padding: 12px;
    border-radius: 8px;
    margin-bottom: 12px;
}

.phrase-pair .text p:first-child {
    font-size: 18px;
    font-weight: 600;
    color: var(--color-primary);
}

.phrase-pair .text p:last-child {
    font-size: 14px;
    color: var(--color-text-light);
}

.speak-btn {
    font-size: 24px;
    background: none;
    padding: 8px;
}

.grammar-card {
    background: linear-gradient(135deg, #f5f7fa, #c3cfe2);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: 20px;
    margin-top: 16px;
}

.grammar-card h4 {
    font-size: 20px;
    margin-bottom: 10px;
}

.grammar-card ul {
    list-style-position: inside;
    padding-left: 10px;
}

.lesson-actions {
    margin-top: 24px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

#start-game-btn {
    background-color: var(--color-primary);
    color: white;
    font-weight: 600;
}

#mark-complete-btn {
    background-color: #5cb85c;
    color: white;
}

/* --- Pantalla de Juego (Flashcards)  --- */
.game-mode {
    display: none; /* Ocultar modos por defecto */
}
.game-mode.active {
    display: block;
}

#flashcard-container {
    width: 100%;
    height: 250px;
    perspective: 1000px;
    margin-bottom: 20px;
}

.flashcard-inner {
    position: relative;
    width: 100%;
    height: 100%;
    text-align: center;
    transition: transform 0.6s;
    transform-style: preserve-3d;
    box-shadow: var(--shadow-md);
    border-radius: var(--border-radius);
}

#flashcard-container.is-flipped .flashcard-inner {
    transform: rotateY(180deg);
}

.flashcard-front, .flashcard-back {
    position: absolute;
    width: 100%;
    height: 100%;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    font-size: 24px;
    font-weight: 600;
}

.flashcard-front {
    background-color: var(--color-card-bg);
    border: 1px solid var(--color-border);
    color: var(--color-text);
}

.flashcard-back {
    background-color: var(--color-primary);
    color: white;
    transform: rotateY(180deg);
}

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

/* --- Adaptación a Desktop  --- */
@media (min-width: 768px) {
    .app-container {
        max-width: 1000px; /* Ancho mayor en desktop */
        display: flex;
    }

    /* En desktop, podríamos tener un panel lateral, pero para
       mantener la simpleza de la media query, solo centraremos
       el contenido en una columna más ancha. */
    .screen {
        max-width: 600px;
        margin: 0 auto;
        min-height: 0; /* Quitamos el min-height */
        box-shadow: var(--shadow-md);
        margin-top: 20px;
        border-radius: var(--border-radius);
    }
    
    .screen.active {
        min-height: 80vh; /* Le damos una altura mínima en desktop */
    }

    .chapter-grid {
        grid-template-columns: 1fr 1fr; /* 2 columnas en desktop */
    }
    
    .app-header.sticky {
        /* En desktop, el sticky header no es tan necesario
           o se implementaría de forma diferente */
        position: relative;
    }
}


.footer {
  background: linear-gradient(90deg, #0d0d0d, #1a1a1a);
  color: #fff;
  text-align: center;
  padding: 10px 10px;
  font-size: 0.8rem;
  letter-spacing: 0.9px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer .brand {
  font-weight: 600;
  color: #00c6ff;
}

.footer a {
  color: #00c6ff;
  text-decoration: none;
}

.footer a:hover {
  color: yellow;
  text-decoration: underline;
  transition: color 0.3s ease;
}

.footer .phone {
  margin: 0 5px;
  color: #ccc;
}

@media (max-width: 600px) {
  .footer {
    font-size: 0.8rem;
    padding: 0px 5px;
  }
  .footer .phone {
    display: block;
    
    padding: 0px 5px;
    font-size: 0.7rem;
  }
}