/* =========================
   RESET BÁSICO
========================= */
* {
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
}

/* =========================
   FONDO GENERAL
========================= */
body {
    background-color: #f4f6f8;
    margin: 0;
    padding: 0;
}

/* =========================
   CONTENEDOR PRINCIPAL
========================= */
.form-contenedor {
    max-width: 520px;
    margin: 30px auto;
    padding: 25px;
    border-radius: 6px;
    border: 1px solid #dcdcdc;

    background-color: #ffffff;
    background-image: url('marca-agua.png'); /* marca de agua */
    background-repeat: no-repeat;
    background-position: center;
    background-size: 280px;
}

/* =========================
   IMAGEN SUPERIOR CONTROLADA
========================= */
.form-imagen {
    height: 160px;          /* ALTURA FIJA */
    overflow: hidden;       /* RECORTE REAL */
    margin-bottom: 18px;
    border-radius: 4px;
}

.form-imagen img {
    width: 100%;
    height: 100%;           /* OBLIGATORIO */
    object-fit: cover;      /* RECORTA SIN DEFORMAR */
    display: block;
}


/* =========================
   TÍTULO
========================= */
.form-contenedor h2 {
    text-align: center;
    margin-bottom: 18px;
    font-size: 18px;
    color: #333;
}

/* =========================
   GRUPOS DE CAMPOS
========================= */
.form-grupo {
    margin-bottom: 12px;
}

/* Etiquetas */
.form-grupo label {
    display: block;
    margin-bottom: 4px;
    font-weight: bold;
    font-size: 13px;
    color: #444;
}

/* =========================
   INPUTS Y SELECTS
========================= */
.form-grupo input,
.form-grupo select {
    width: 100%;
    height: 32px;                 /* altura compacta real */
    padding: 4px 8px;
    line-height: 1.1;
    border: 1px solid #bfc5ca;
    border-radius: 4px;
    font-size: 13px;
    background-color: #ffffff;
}

/* Foco */
.form-grupo input:focus,
.form-grupo select:focus {
    outline: none;
    border-color: #4a7fb4;
}

/* =========================
   BOTÓN
========================= */
.form-boton {
    width: 100%;
    height: 36px;
    margin-top: 10px;
    background-color: #2f6da1;
    color: #ffffff;
    border: none;
    border-radius: 4px;
    font-size: 14px;
    font-weight: bold;
    cursor: pointer;
}

.form-boton:hover {
    background-color: #245682;
}

/* =========================
   MENSAJES
========================= */
.mensaje-exito {
    background-color: #e6f4ea;
    color: #256029;
    border: 1px solid #b7dfc0;
    padding: 10px;
    margin-bottom: 12px;
    border-radius: 4px;
    font-size: 13px;
}

.mensaje-error {
    background-color: #fdecea;
    color: #a4282d;
    bo