/* Estilos Generales y Variables */
:root {
    --primary-color: #005f73;
    --secondary-color: #0a9396;
    --background-color: #e9d8a6;
    --card-bg-color: #ee9b00;
    --text-color: #001219;
    --light-text-color: #ffffff;
    --border-radius: 8px;
    --box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* --- Pantalla de Selección de Asignatura --- */
#course-selector-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.6);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

#course-selector-screen.active {
    opacity: 1;
    visibility: visible;
}

.course-selector-modal {
    background-color: white;
    padding: 2rem 3rem;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: 0 5px 15px rgba(0,0,0,0.3);
}

#course-buttons-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-top: 1.5rem;
}

.course-btn {
    padding: 0.8rem 1.5rem;
    border: none;
    background-color: var(--primary-color);
    color: var(--light-text-color);
    font-size: 1.1rem;
    font-weight: bold;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: background-color 0.2s ease;
    text-transform: capitalize;
}

.course-btn:hover {
    background-color: var(--secondary-color);
}


/* --- Contenedor Principal de la App --- */
#app-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1.5rem;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 1.5rem;
    border-bottom: 2px solid var(--secondary-color);
    padding-bottom: 1rem;
}

header h1 {
    margin: 0;
    color: var(--primary-color);
}

#change-course-btn {
    background: none;
    border: 2px solid var(--secondary-color);
    color: var(--secondary-color);
    font-weight: bold;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all 0.2s ease;
}

#change-course-btn:hover {
    background-color: var(--secondary-color);
    color: white;
}

/* --- Controles de Búsqueda --- */
.controls-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.controls-container input,
.controls-container select,
.controls-container button {
    width: 100%;
    padding: 0.8rem;
    border: 1px solid #ccc;
    border-radius: var(--border-radius);
    font-size: 1rem;
    box-sizing: border-box;
}

.controls-container button {
    background-color: var(--secondary-color);
    color: var(--light-text-color);
    border: none;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

.controls-container button:hover {
    background-color: var(--primary-color);
}

/* --- Contenedor de Resultados --- */
#results-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.exercise-card {
    background-color: var(--card-bg-color);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    padding: 1rem;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    display: flex;
    flex-direction: column;
}

.exercise-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.15);
}

.card-banner {
    font-weight: bold;
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    flex-grow: 1;
}

.card-file {
    font-size: 0.9rem;
    opacity: 0.8;
    word-break: break-all;
}

/* --- Visor de PDF --- */
#pdf-viewer-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 2000;
}

.pdf-viewer-content {
    background-color: #333;
    width: 90%;
    height: 90%;
    max-width: 1000px;
    border-radius: var(--border-radius);
    position: relative;
    display: flex;
    flex-direction: column;
}

#close-pdf-btn {
    position: absolute;
    top: -15px;
    right: -15px;
    background-color: white;
    color: black;
    border: none;
    border-radius: 50%;
    width: 35px;
    height: 35px;
    font-size: 1.8rem;
    line-height: 35px;
    text-align: center;
    cursor: pointer;
    box-shadow: var(--box-shadow);
}

#pdf-embed-container {
    flex-grow: 1;
    padding: 10px;
}

#pdf-embed-container embed {
    width: 100%;
    height: 100%;
    border: none;
    border-radius: var(--border-radius);
}


/* --- Clases de Utilidad --- */
.hidden {
    display: none !important;
}

/* --- Diseño Responsive --- */
@media (max-width: 768px) {
    header {
        text-align: center;
        justify-content: center;
    }
    
    .course-selector-modal {
        width: 80%;
        padding: 1.5rem;
    }
}