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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: white;
    color: #333;
    min-height: 100vh;
    padding: 4px;
}

#ejercicio-1 {
    background: linear-gradient(135deg, #f5f7fa, #c3cfe288);
}

.container {
    max-width: 100%;
    margin: 0 auto;
    background: white;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    padding: 15px;
}

.container-index {
    max-width: 100%;
}

.subtitle {
    text-align: center;
    color: #7f8c8d;
    margin-bottom: 20px;
    font-size: 0.9rem;
}

.ejercicios-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 15px;
}

.ejercicio-card {
    background: #ecf0f1;
    padding: 15px;
    border-radius: 8px;
    text-decoration: none;
    color: #2c3e50;
    transition: transform 0.3s, box-shadow 0.3s;
    display: block;
}

.ejercicio-card h2 {
    margin-bottom: 8px;
    color: #3498db;
    font-size: 1.2rem;
}

.ejercicio-card p {
    color: #7f8c8d;
    font-size: 0.85rem;
}

/* Botones - Mobile First */
.btn {
    background: #3498db;
    color: white;
    border: none;
    padding: 12px 20px;
    border-radius: 5px;
    cursor: pointer;
    font-size: 14px;
    margin: 5px 0;
    transition: background 0.3s;
}

.btn-danger {
    background: #e74c3c;
}

.lista .btn-danger {
    color: #fff;    
    padding: 2px 8px;
    border-radius: 3px;
    border-style: none;
    width: fit-content;
}

.btn-success {
    background: #27ae60;
}

.btn-warning {
    background: #f39c12;
}

/* Formularios */
input[type=button], input[type=text], input[type=number], textarea, select {
    width: 100%;
    padding: 12px;
    margin: 8px 0;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 16px;
}

input[type=button]:focus, input[type=text]:focus, textarea:focus {
    outline: none;
    border-color: #3498db;
}


/* Listas */
.lista {
    list-style: none;
    margin-top: 20px;    
}

.lista li {
    background: #ecf0f1;
    margin: 10px 0 0 0;
    border-radius: 5px;
    padding: 15px;
}

#listaDinamica li, #listaTareas li {
    border-radius: 5px;
    display: flex;
    justify-content: space-between;    
    align-items: center;
    gap: 8px;    
}

#listaElementos{
    display: flex;
    column-gap: 8px;
    text-wrap: nowrap;
    flex-wrap: wrap; 
}

.tarea-item.completada {
    text-decoration: line-through;
    opacity: 0.6;
}

.lista-texto {
    word-break: break-word;
    flex-grow: 2;
}

.back-link {
    display: inline-block;
    margin-top: 20px;
    color: #3498db;
    text-decoration: none;
    padding: 10px;
    border-radius: 5px;
    transition: background 0.3s;
}

.button-group {
    justify-content: center;
    margin: 20px 0;
}

.grid-4 {
    display: grid;
    grid-template-columns: repeat(1, 1fr);
    gap: 0;
    margin: 10px 0;
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(1, 1fr);
    gap: 0;
}

.grid-2 {
    display: grid;
    grid-template-columns: repeat(1, 1fr);
    gap: 0;
} 

.temporizador, .resultado {
    text-align: center;
    font-family: monospace;
    margin: 20px 0;
    padding: 20px;
    background: #2c3e50;
    color: #ecf0f1;
    border-radius: 10px;
    word-break: break-word;
    text-wrap: balance;    
}

.temporizador {
    font-size: 32px;
}

.resultado {
    font-size: 24px;
    margin: 8px 0;
}

#password {
    font-size: 16px;
}

.estado-temporizador {
    font-size: 14px;
    text-align: center;
    margin-top: 10px;
    color: #7f8c8d;
}

.card {
    background: #f8f9fa;
    border-radius: 8px;
    padding: 15px;
    margin: 15px 0;
}

#dale {
    margin-top: 20px; 
    font-size: 1.2rem; 
    font-weight: bold; 
    color: #ff6b6b;
    min-height: 60px;
}

.ejercicios-nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.main-footer {
    margin-top: 2rem;
    padding: 1rem;
    background-color: #f5f5f5;
    border-radius: 8px;
    text-align: center;
}

.creator-link {
    color: #3498db;
    text-decoration: none;
    font-weight: bold;
}

.creator-link:hover {
    text-decoration: underline;
}

.text-center {
    text-align: center;
}

.exercise-header {
    text-align: center;
    margin-bottom: 25px;
}

.exercise-header h1 {
    font-size: 24px;
    line-height: 30px;    
    color: #2c3e50;
    margin-bottom: 10px;
    text-wrap: balance;
}


/* ============================================ */
/* MEDIA QUERIES PARA PANTALLAS MÁS GRANDES */
/* ============================================ */
@media (min-width: 480px) {

    body {
        padding: 10px;
    }
    
    .ejercicios-grid {
        grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
        gap: 20px;
    }

    .grid-4 {
        grid-template-columns: repeat(2, 1fr);
        column-gap: 8px;
    }
    
    .grid-3 {
        grid-template-columns: repeat(3, 1fr);
        gap: 8px;
    }
    
    .grid-2 {
        grid-template-columns: repeat(2, 1fr);
        gap: 8px;
    } 

    #password {
        font-size: 18px;
    }

    .exercise-header {
        margin-bottom: 30px;
    }

    .exercise-header h1 {
        font-size: 26px;
        line-height: 34px;
    }    
}

/* ============================================ */
/* MEDIA QUERIES PARA PANTALLAS MÁS GRANDES */
/* ============================================ */

@media (min-width: 768px) {
    body {
        padding: 20px;
    }
    
    .container {
        max-width: 800px;
        padding: 30px;
    }
    
    .container-index {
        max-width: 1024px;
    }
    
    .subtitle {
        font-size: 1rem;
        margin-bottom: 30px;
    }
       
    .ejercicio-card {
        padding: 20px;
    }
    
    .ejercicio-card:hover {
        transform: translateY(-5px);
        box-shadow: 0 5px 20px rgba(0,0,0,0.15);
    }
    
    .ejercicio-card h2 {
        font-size: 1.5rem;
    }
    
    .btn {
        padding: 10px 20px;
        font-size: 16px;
        width: auto;
        margin: 5px;
    }

    .btn:hover {
        opacity: 0.9;
        transform: translateY(-2px);
    }

    .grid-4 {
        display: grid;
        grid-template-columns: repeat(4, 1fr);
    }

    .tarea-item input[type=checkbox] {
        position: unset;
    }
   
    .tarea-item {
        flex-direction: row;
        align-items: center;
    }

    .temporizador, .resultado {
        font-size: 36px;
    }
    
    #password {
        font-size: 22px;
    }

    .exercise-header {
        margin-bottom: 35px;
    }

    .exercise-header h1 {
        font-size: 30px;
        margin-bottom: 10px;
    }
    
    .main-footer {
        margin-top: 3rem;
        padding: 1.5rem;
    }
    
    .back-link:hover {
        background: #ecf0f1;
    }
    
    #dale {
        font-size: 1.5rem;
    }
}