:root {
    --primary: #2E86AB;
    --primary-dark: #1B5E7A;
    --primary-light: #5BA4C8;
    --secondary: #6C757D;

    --background: #F8F9FA;
    --surface: #FFFFFF;
    --text: #212529;
    --text-light: #6C757D;
    --border: #DEE2E6;

    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 2px 6px rgba(0, 0, 0, 0.1);

    --radius: 12px;
}

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

/* Fondo centrado */
.fondo {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: var(--background);
    padding: 20px;
}

/* Contenedor minimalista y profesional */
.contenedor {
    background-color: var(--surface);
    padding: 35px 30px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    max-width: 480px;
    width: 100%;
    text-align: center;
    transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.contenedor:hover {
    transform: translateY(-5px) scale(1.02);
    box-shadow: 0 8px 20px rgba(0,0,0,0.15);
}

h1, h2 {
    font-size: 2rem;
    margin-bottom: 20px;
    color: var(--primary);
    letter-spacing: 0.5px;
}

p {
    font-size: 1.05rem;
    margin-bottom: 30px;
    color: var(--text-light);
    line-height: 1.5;
}

/* Labels y campos de formulario */
label {
    display: block;
    margin-bottom: 5px;
    font-weight: 600;
    color: var(--text);
    text-align: left;
}

input[type="text"], input[type="password"] {
    width: 100%;
    padding: 12px;
    margin: 8px 0 20px 0;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    font-size: 1rem;
}

/* Botón profesional */
.boton {
    display: inline-block;
    padding: 14px 35px;
    font-size: 1.1rem;
    color: #fff;
    background-color: var(--primary);
    border-radius: var(--radius);
    text-decoration: none;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
}

.boton:hover {
    background-color: var(--primary-dark);
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

/* Mensajes de alerta AJAX */
#loginMensaje {
    margin-top: 15px;
    font-weight: 600;
    font-size: 1rem;
}

.alerta-exito {
    color: green;
}

.alerta-error {
    color: red;
}

/* Responsive tablets (iPad Air 4) */
@media (min-width: 768px) and (max-width: 820px) {
    h1, h2 {
        font-size: 2.2rem;
    }
    p {
        font-size: 1.15rem;
    }
    .boton {
        font-size: 1.2rem;
        padding: 16px 40px;
    }
    input[type="text"], input[type="password"] {
        font-size: 1.05rem;
        padding: 14px;
    }
}