* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Arial, sans-serif;
}
body {
    background: #eef2f3;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}
.contenedor-formulario {
    background: #ffffff;
    padding: 35px;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.15);
    width: 100%;
    max-width: 380px;
}
h2 {
    margin-bottom: 25px;
    color: #2c3e50;
    text-align: center;
}
.grupo-control {
    margin-bottom: 18px;
}
label {
    display: block;
    margin-bottom: 6px;
    color: #34495e;
    font-size: 14px;
    font-weight: 600;
}
input {
    width: 100%;
    padding: 12px;
    border: 1px solid #cbd5e1;
    border-radius: 6px;
    font-size: 15px;
}
input:focus {
    border-color: #3498db;
    outline: none;
}
button {
    width: 100%;
    padding: 13px;
    background: #3498db;
    border: none;
    color: white;
    font-size: 16px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: bold;
    transition: background 0.2s;
}
button:hover {
    background: #2980b9;
}
.alerta {
    padding: 12px;
    border-radius: 6px;
    margin-bottom: 18px;
    font-size: 14px;
    font-weight: 500;
}
.error {
    background: #fde8e8;
    color: #9b1c1c;
    border: 1px solid #f8b4b4;
}