/* Reset y configuración base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Colores principales */
    --primary-gradient: linear-gradient(135deg, #6e8efb, #a777e3);
    --header-gradient: linear-gradient(135deg, #da891f, #e0d31b);
    --success: #28a745;
    --error: #dc3545;
    --warning: #ffc107;
    --info: #17a2b8;
    
    /* Colores de fondo */
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --bg-card: #ffffff;
    
    /* Sombras */
    --shadow-light: 0 4px 15px rgba(0, 0, 0, 0.1);
    --shadow-medium: 0 10px 30px rgba(0, 0, 0, 0.15);
    --shadow-strong: 0 4px 15px rgba(0, 0, 0, 0.2);
    
    /* Transiciones */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Tipografía */
    --font-main: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-mono: 'Consolas', 'Courier New', monospace;
    
    /* Espaciado */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 12px;
    --spacing-lg: 16px;
    --spacing-xl: 20px;
    --spacing-xxl: 24px;
    --spacing-xxxl: 30px;
    
    /* Bordes */
    --border-radius-sm: 8px;
    --border-radius-md: 12px;
    --border-radius-lg: 15px;
}

body {
    font-family: var(--font-main);
    background: var(--primary-gradient);
    min-height: 100vh;
    padding: 20px;
    color: #333;
    line-height: 1.6;
}

/* Layout general */
.screen {
    max-width: 1000px;
    margin: 0 auto;
    padding: var(--spacing-xxxl);
    background: var(--bg-card);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-medium);
    transition: all var(--transition-normal);
}

.hidden {
    display: none !important;
}

/* Pantalla de login */
#login-screen {
    text-align: center;
    padding: 40px 20px;
}

#login-screen h1 {
    color: #5d4037;
    margin-bottom: var(--spacing-xl);
    font-size: 1.75rem;
    font-weight: 700;
}

#login-screen input {
    width: 100%;
    max-width: 300px;
    padding: var(--spacing-md);
    margin: var(--spacing-lg) 0;
    border: 2px solid #ddd;
    border-radius: var(--border-radius-sm);
    font-size: 1rem;
    outline: none;
    transition: border-color var(--transition-normal);
    font-family: var(--font-main);
}

#login-screen input:focus {
    border-color: #6e8efb;
    box-shadow: 0 0 0 3px rgba(110, 142, 251, 0.2);
}

#login-screen button {
    background: #6e8efb;
    color: white;
    border: none;
    padding: var(--spacing-md) var(--spacing-xxl);
    border-radius: var(--border-radius-sm);
    font-size: 1.125rem;
    cursor: pointer;
    transition: all var(--transition-normal);
    font-weight: 600;
    box-shadow: var(--shadow-light);
}

#login-screen button:hover {
    background: #5d4037;
    transform: translateY(-2px);
    box-shadow: var(--shadow-strong);
}

#login-screen button:active {
    transform: translateY(0);
}

/* Encabezado de la app */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-xl);
    background: var(--header-gradient);
    border-radius: var(--border-radius-lg);
    margin-bottom: var(--spacing-xxl);
    box-shadow: var(--shadow-strong);
    color: white;
    position: relative;
    overflow: hidden;
}

header::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    transform: rotate(30deg);
}

.student-info {
    display: flex;
    gap: 25px;
    font-weight: bold;
    align-items: center;
    flex-wrap: wrap;
    justify-content: center;
}

/* Nombre del estudiante */
#currentStudent {
    background: linear-gradient(135deg, #5b26d8, #e79a85);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 1.375rem;
    font-weight: 800;
    text-shadow: 0 2px 4px rgba(0,0,0,0.1);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--border-radius-md);
    background-color: rgba(255,255,255,0.15);
    backdrop-filter: blur(10px);
    border: 2px solid rgba(255,255,255,0.3);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
}

#currentStudent::before {
    content: '👤';
    font-size: 1.5rem;
}

/* Puntaje */
#score {
    background: linear-gradient(135deg, #fe724f, #fe9800);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 1.5rem;
    font-weight: 800;
    text-shadow: 0 2px 4px rgba(0,0,0,0.1);
    padding: var(--spacing-md) var(--spacing-xl);
    border-radius: var(--border-radius-lg);
    background-color: rgba(255,255,255,0.15);
    backdrop-filter: blur(10px);
    border: 2px solid rgba(255,255,255,0.3);
    min-width: 140px;
    text-align: center;
    position: relative;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
}

#score::before {
    content: '⭐';
    font-size: 1.625rem;
}

/* Badge animado para el puntaje */
#score::after {
    content: '';
    position: absolute;
    top: -5px;
    right: -5px;
    width: 15px;
    height: 15px;
    background: #ffeb3b;
    border-radius: 50%;
    box-shadow: 0 0 10px #ffeb3b;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% { box-shadow: 0 0 0 0 rgba(255, 235, 59, 0.7); }
    70% { box-shadow: 0 0 0 10px rgba(255, 235, 59, 0); }
    100% { box-shadow: 0 0 0 0 rgba(255, 235, 59, 0); }
}

/* Contenedor del ejercicio */
#exercise-container {
    margin-bottom: var(--spacing-xxl);
}

#data-description {
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: #333;
    font-size: 1.125rem;
    padding: var(--spacing-md);
    background: #e8f5e9;
    border-left: 4px solid var(--success);
    border-radius: var(--border-radius-sm);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

#data-description::before {
    content: '📊';
    font-size: 1.25rem;
}

#data-values {
    background: var(--bg-light);
    padding: var(--spacing-md);
    border-radius: var(--border-radius-sm);
    margin-bottom: var(--spacing-xl);
    font-family: var(--font-mono);
    word-break: break-all;
    border: 1px solid #e9ecef;
    font-size: 1.125rem;
    line-height: 1.4;
}

/* Tabla de frecuencias */
#frequency-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: var(--spacing-lg);
    background: #fff;
    border-radius: var(--border-radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-light);
    margin-bottom: var(--spacing-xxl);
}

#frequency-table th,
#frequency-table td {
    padding: var(--spacing-md);
    text-align: center;
    border: 1px solid #e0e0e0;
    font-size: 0.95rem;
}

#frequency-table th {
    background: #f8f9fa;
    font-weight: 700;
    color: #495057;
    position: relative;
}

#frequency-table th[colspan] {
    background: #e9ecef;
    color: #495057;
}

#frequency-table tr:nth-child(even) {
    background-color: #fafafa;
}

#frequency-table tr:hover {
    background-color: #f1f3f5;
}

/* Retroalimentación */
#feedback {
    padding: var(--spacing-lg);
    margin: var(--spacing-xl) 0;
    border-radius: var(--border-radius-sm);
    font-weight: 700;
    text-align: center;
    font-size: 1.125rem;
    opacity: 0;
    transform: translateY(-10px);
    animation: fadeInShow 0.5s ease-out forwards;
}

@keyframes fadeInShow {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

#feedback.correct {
    background: #e8f5e9;
    color: #155724;
    border: 2px solid #81c784;
    animation: bounce 0.6s ease;
}

#feedback.incorrect {
    background: #ffebee;
    color: #721c24;
    border: 2px solid #ef9a9a;
}

#feedback.blocked {
    background: #fff3e0;
    color: #e65100;
    border: 2px solid #ffb74d;
}

/* Botones de control */
.controls {
    display: flex;
    gap: var(--spacing-lg);
    justify-content: center;
    margin-top: var(--spacing-xxl);
    flex-wrap: wrap;
}

.controls button {
    padding: var(--spacing-md) var(--spacing-xxl);
    border: none;
    border-radius: var(--border-radius-sm);
    font-size: 1rem;
    cursor: pointer;
    transition: all var(--transition-normal);
    min-width: 150px;
    font-weight: 600;
    box-shadow: var(--shadow-light);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.controls button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.controls button:not(:disabled):hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.25);
}

.controls button:not(:disabled):active {
    transform: translateY(-1px);
}

#checkBtn {
    background: linear-gradient(135deg, #ff9800, #ff5722);
    color: white;
}

#checkBtn:hover:not(:disabled) {
    background: linear-gradient(135deg, #f57c00, #e64a19);
}

#nextBtn {
    background: linear-gradient(135deg, #4caf50, #2e7d32);
    color: white;
}

#nextBtn:hover:not(:disabled) {
    background: linear-gradient(135deg, #388e3c, #1b5e20);
}

/* Animación de rebote */
@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-12px); }
    60% { transform: translateY(-6px); }
}

/* Contenedor de preguntas */
#questions-container {
    margin-top: var(--spacing-xxl);
    padding: var(--spacing-xl);
    background: var(--bg-light);
    border-radius: var(--border-radius-md);
    border: 2px solid #e9ecef;
}

#questions-container h3 {
    margin-bottom: var(--spacing-lg);
    color: #5d4037;
    text-align: center;
    font-size: 1.375rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

#questions-container h3::before {
    content: '❓';
}

.question-item {
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: var(--bg-white);
    border-radius: var(--border-radius-md);
    box-shadow: var(--shadow-light);
    border-left: 4px solid #6e8efb;
    transition: transform var(--transition-fast);
}

.question-item:hover {
    transform: translateX(4px);
}

.question-text {
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: #333;
    font-size: 1.125rem;
    line-height: 1.4;
}

.options-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.option-btn {
    padding: var(--spacing-md);
    border: 2px solid #ddd;
    border-radius: var(--border-radius-sm);
    background: var(--bg-white);
    cursor: pointer;
    text-align: center;
    transition: all var(--transition-normal);
    font-weight: 600;
    min-height: 55px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1rem;
    line-height: 1.2;
}

.option-btn:hover:not(:disabled):not(.correct):not(.incorrect) {
    background: #f0f7ff;
    border-color: #6e8efb;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(110, 142, 251, 0.2);
}

.option-btn.selected:not(.correct):not(.incorrect) {
    background: #e3f2fd;
    border-color: #2196f3;
    box-shadow: 0 0 0 3px rgba(33, 150, 243, 0.3);
    transform: scale(1.02);
}

.option-btn.correct {
    background: #d4edda !important;
    border-color: var(--success) !important;
    color: #155724 !important;
    box-shadow: 0 0 0 3px rgba(40, 167, 69, 0.3) !important;
    cursor: default !important;
    transform: scale(1.03) !important;
    font-weight: 700 !important;
    position: relative;
}

.option-btn.correct::after {
    content: '✓';
    position: absolute;
    top: -8px;
    right: -8px;
    background: var(--success);
    color: white;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: bold;
}

.option-btn.incorrect {
    background: #f8d7da !important;
    border-color: var(--error) !important;
    color: #721c24 !important;
    box-shadow: 0 0 0 3px rgba(220, 53, 69, 0.3) !important;
    cursor: default !important;
    transform: scale(1.03) !important;
    font-weight: 700 !important;
    position: relative;
}

.option-btn.incorrect::after {
    content: '✗';
    position: absolute;
    top: -8px;
    right: -8px;
    background: var(--error);
    color: white;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: bold;
}

.option-btn:disabled {
    opacity: 1;
    cursor: default;
}

/* Responsive */
@media (max-width: 768px) {
    .screen {
        padding: var(--spacing-xl) var(--spacing-md);
    }

    header {
        flex-direction: column;
        gap: var(--spacing-lg);
        padding: var(--spacing-lg);
    }

    .student-info {
        flex-direction: column;
        gap: var(--spacing-md);
        align-items: center;
    }

    #currentStudent, #score {
        font-size: 1.125rem;
        padding: var(--spacing-sm) var(--spacing-md);
        min-width: auto;
    }

    #score::after {
        top: -3px;
        right: -3px;
        width: 12px;
        height: 12px;
    }

    .controls button {
        width: 100%;
        max-width: 300px;
        min-width: auto;
    }

    #frequency-table th,
    #frequency-table td {
        padding: var(--spacing-sm);
        font-size: 0.85rem;
    }

    .question-text {
        font-size: 1rem;
    }
}

@media (max-width: 600px) {
    .options-container {
        grid-template-columns: 1fr;
    }
    
    .option-btn {
        min-height: 48px;
        padding: var(--spacing-md) var(--spacing-lg);
    }
    
    #currentStudent, #score {
        font-size: 1rem;
        padding: var(--spacing-xs) var(--spacing-md);
    }
    
    header {
        padding: var(--spacing-md);
    }
    
    #data-values {
        font-size: 1rem;
    }
}

/* Accesibilidad mejorada */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus para accesibilidad */
.option-btn:focus,
#login-screen input:focus,
.controls button:focus {
    outline: 2px solid #007bff;
    outline-offset: 2px;
}

/* Mejora de contraste para texto */
.question-text,
#data-description {
    color: #212529;
}

/* Efecto sutil para la tabla */
#frequency-table {
    border: 1px solid #dee2e6;
}