body {
    width: 100vw;
    height: 100vh;
    font-family: 'Arial', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: #333;
    margin: 0;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
}

header {
    width: 100%;
    height: 80px;
    background-color: black;

    display: flex;

    justify-content: space-around;
    align-items: center;
}

ul {
    display: flex;

    gap: 15px;

    list-style: none;
}

a {
    text-decoration: none;

    font-size: x-large;
    font-family: Arial, Helvetica, sans-serif;

    color: black;

    padding: 8px;

    background-color: white;

    border: 5px
}

h1 {
    text-align: center;
    color: white;
    font-size: 2.5em;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
    margin-bottom: 30px;
}

.ejercicio {
    background: rgba(255,255,255,0.95);
    border-radius: 15px;
    padding: 25px;
    margin: 20px 0;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
    backdrop-filter: blur(10px);
}

.ejercicio h2 {
    color: #2c3e50;
    border-bottom: 3px solid #3498db;
    padding-bottom: 10px;
    margin-bottom: 20px;
}

.instrucciones {
    background: #fff3cd;
    border: 1px solid #ffeaa7;
    border-radius: 8px;
    padding: 15px;
    margin-bottom: 20px;
    border-left: 4px solid #f39c12;
}

.instrucciones h4 {
    color: #856404;
    margin-top: 0;
}

.instrucciones ol {
    margin: 10px 0;
    padding-left: 20px;
}

.pista {
    background: #d1ecf1;
    border: 1px solid #bee5eb;
    border-radius: 5px;
    padding: 10px;
    margin: 10px 0;
    border-left: 4px solid #17a2b8;
    font-size: 0.9em;
}

.btn {
    background: linear-gradient(45deg, #3498db, #2980b9);
    color: white;
    border: none;
    padding: 12px 25px;
    border-radius: 25px;
    cursor: pointer;
    font-size: 1em;
    margin: 5px;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(52, 152, 219, 0.3);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(52, 152, 219, 0.4);
}

.btn.danger {
    background: linear-gradient(45deg, #e74c3c, #c0392b);
    box-shadow: 0 4px 15px rgba(231, 76, 60, 0.3);
}

.btn.success {
    background: linear-gradient(45deg, #27ae60, #229954);
    box-shadow: 0 4px 15px rgba(39, 174, 96, 0.3);
}

.resultado {
    background: #f8f9fa;
    border-left: 4px solid #3498db;
    padding: 15px;
    margin: 15px 0;
    border-radius: 5px;
    font-family: 'Courier New', monospace;
}

.lista-items {
    background: #ecf0f1;
    padding: 15px;
    border-radius: 8px;
    margin: 10px 0;
}

.lista-items li {
    padding: 8px;
    margin: 5px 0;
    background: white;
    border-radius: 5px;
    border-left: 4px solid #3498db;
    transition: all 0.3s ease;
}

.lista-items li:hover {
    background: #3498db;
    color: white;
    transform: translateX(5px);
}

.contador {
    font-size: 3em;
    font-weight: bold;
    text-align: center;
    color: #2c3e50;
    background: #ecf0f1;
    border-radius: 10px;
    padding: 20px;
    margin: 15px 0;
}

.galeria {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
    gap: 10px;
    margin: 15px 0;
}

.imagen-item {
    font-size: 4em;
    text-align: center;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.imagen-item:hover {
    transform: scale(1.1);
    background: #3498db;
}

.formulario {
    background: #f8f9fa;
    padding: 20px;
    border-radius: 8px;
    margin: 15px 0;
}

.formulario input, .formulario select {
    width: 100%;
    padding: 12px;
    margin: 8px 0;
    border: 2px solid #bdc3c7;
    border-radius: 5px;
    font-size: 1em;
    box-sizing: border-box;
}

.formulario input:focus, .formulario select:focus {
    border-color: #3498db;
    outline: none;
}

.tarjeta {
    background: white;
    border-radius: 10px;
    padding: 15px;
    margin: 10px 0;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    border-left: 4px solid #3498db;
}

.codigo-ejemplo {
    background: #2d3748;
    color: #68d391;
    padding: 15px;
    border-radius: 8px;
    font-family: 'Courier New', monospace;
    margin: 10px 0;
    font-size: 0.9em;
    overflow-x: auto;
}

.no-completado {
    opacity: 0.6;
    pointer-events: none;
}