* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
    background: #eef3f7;
    color: #172b3a;
}


/* =========================
   CABECERA
========================= */

.topbar {
    background: #092c4c;
    color: white;
    padding: 18px 5%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
}

.marca {
    display: flex;
    align-items: center;
    gap: 15px;
}

.logo-dga {
    width: 58px;
    height: 58px;
    background: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.logo-dga img {
    width: 50px;
    height: 50px;
    object-fit: contain;
}

.topbar h1 {
    margin: 0;
    font-size: 25px;
}

.topbar p {
    margin: 4px 0 0;
    color: #b9d7eb;
}

.estado-general {
    display: flex;
    align-items: center;
    gap: 10px;
}

.estado-general strong {
    display: block;
}

.estado-general small {
    color: #b9d7eb;
}

.punto-verde {
    width: 12px;
    height: 12px;
    background: #28c76f;
    border-radius: 50%;
    box-shadow: 0 0 10px #28c76f;
}


/* =========================
   CONTENEDOR
========================= */

.contenedor {
    width: 94%;
    max-width: 1250px;
    margin: 30px auto;
}


/* =========================
   HERO
========================= */

.hero {
    position: relative;
    height: 330px;
    border-radius: 18px;
    overflow: hidden;
    margin-bottom: 30px;
    box-shadow: 0 8px 25px rgba(0,0,0,.12);
}

.hero img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.hero-texto {
    position: absolute;
    left: 35px;
    bottom: 30px;
    color: white;
    max-width: 500px;
    text-shadow: 0 2px 5px rgba(0,0,0,.7);
}

.hero-texto span {
    font-size: 13px;
    font-weight: bold;
    letter-spacing: 2px;
}

.hero-texto h2 {
    font-size: 32px;
    margin: 8px 0;
}

.hero-texto p {
    margin: 0;
}


/* =========================
   POZOS
========================= */

.pozos {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 25px;
    margin-bottom: 30px;
}

.pozo-card {
    background: white;
    border-radius: 18px;
    padding: 25px;
    box-shadow: 0 5px 20px rgba(0,0,0,.08);
    border-left: 5px solid #168aad;
}

.pozo-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.pozo-header h2 {
    margin: 8px 0 0;
    font-size: 25px;
}

.estado-pozo {
    font-size: 12px;
    font-weight: bold;
    color: #1d9b57;
}

.estado-pozo i {
    display: inline-block;
    width: 8px;
    height: 8px;
    background: #28c76f;
    border-radius: 50%;
    margin-right: 5px;
}

.numero-pozo {
    font-size: 40px;
    font-weight: bold;
    color: #e3ebf1;
}


/* =========================
   ALERTA NIVEL BAJO
========================= */

.alerta-nivel {
    margin-top: 10px;
    padding: 8px 14px;
    border-radius: 8px;
    font-size: 13px;
    font-weight: bold;
    transition: all 0.3s ease;
}

.nivel-normal {
    display: none;
}

.alerta-roja {
    display: inline-block;
    background: #d32f2f;
    color: white;
    animation: parpadeoAlerta 1s infinite;
}

@keyframes parpadeoAlerta {
    0%, 100% {
        opacity: 1;
    }

    50% {
        opacity: 0.55;
    }
}


/* =========================
   MEDICIONES
========================= */

.mediciones {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
    margin-top: 25px;
}


.mediciones {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
    margin-top: 25px;
}

.medicion {
    text-align: center;
    background: #f5f8fa;
    border-radius: 12px;
    padding: 15px 5px;
}

.medicion span {
    display: block;
    color: #71808c;
    font-size: 11px;
    font-weight: bold;
}

.medicion strong {
    display: block;
    font-size: 27px;
    color: #0b6e9e;
    margin: 7px 0 2px;
}

.medicion small {
    color: #71808c;
}

.ultima {
    margin-top: 18px;
    padding-top: 15px;
    border-top: 1px solid #e8edf1;
    font-size: 12px;
    color: #71808c;
}

.ultima strong {
    margin-left: 5px;
    color: #34495e;
}


/* =========================
   PANEL GRAFICO
========================= */

.panel-grafico,
.historial {
    background: white;
    border-radius: 18px;
    padding: 25px;
    margin-bottom: 30px;
    box-shadow: 0 5px 20px rgba(0,0,0,.07);
}

.titulo-panel,
.historial-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
    margin-bottom: 20px;
}

/* =========================
   CONTROLES HISTORIAL
========================= */

.historial-controles {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
}

.boton-exportar {
    display: inline-block;
    background: #168aad;
    color: white;
    text-decoration: none;
    padding: 10px 14px;
    border-radius: 8px;
    font-size: 14px;
    font-weight: bold;
    transition: all 0.2s ease;
}

.boton-exportar:hover {
    background: #0b6e9e;
    transform: translateY(-1px);
}

.boton-exportar:active {
    transform: translateY(0);
}

.titulo-panel h2,
.historial h2 {
    margin: 5px 0 0;
}

.etiqueta {
    color: #168aad;
    font-size: 11px;
    font-weight: bold;
    letter-spacing: 2px;
}

.controles {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

select {
    border: 1px solid #d5dee5;
    background: white;
    padding: 10px 14px;
    border-radius: 8px;
    font-size: 14px;
    color: #34495e;
}

.grafico {
    position: relative;
    height: 380px;
}


/* =========================
   TABLA
========================= */

.tabla-scroll {
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
    min-width: 700px;
}

th {
    background: #092c4c;
    color: white;
    padding: 14px 10px;
    text-align: center;
    font-size: 13px;
}

td {
    padding: 12px 10px;
    text-align: center;
    border-bottom: 1px solid #edf1f4;
    font-size: 13px;
}

tbody tr:hover {
    background: #f2f8fb;
}

.badge {
    display: inline-block;
    background: #e8f4f8;
    color: #08779d;
    border-radius: 20px;
    padding: 5px 10px;
    font-size: 11px;
    font-weight: bold;
}


/* =========================
   FOOTER
========================= */

footer {
    background: #092c4c;
    color: white;
    text-align: center;
    padding: 25px;
}

footer strong {
    display: block;
}

footer span {
    color: #b9d7eb;
    font-size: 13px;
}


/* =========================
   CELULAR
========================= */

.topbar {
        flex-direction: column;
        text-align: center;
    }

    .marca {
        flex-direction: column;
    }

    .pozos {
        grid-template-columns: 1fr;
    }

    .titulo-panel,
    .historial-header {
        flex-direction: column;
        align-items: stretch;
    }

    .controles {
        flex-direction: column;
    }

    select {
        width: 100%;
    }

    .hero {
        height: 280px;
    }

    .hero-texto {
        left: 20px;
        bottom: 20px;
    }

    .hero-texto h2 {
        font-size: 24px;
    }

    .mediciones {
        grid-template-columns: 1fr;
    }

    .grafico {
        height: 300px;
    }

}
Agrega esto antes del último }

Es decir, justo después de:

    .grafico {
        height: 300px;
    }

pon:

    .historial-controles {
        flex-direction: column;
        align-items: stretch;
    }

    .historial-controles select,
    .boton-exportar {
        width: 100%;
        text-align: center;
    }

@media (max-width: 800px) {

    .topbar {
        flex-direction: column;
        text-align: center;
    }

    .marca {
        flex-direction: column;
    }

    .pozos {
        grid-template-columns: 1fr;
    }

    .titulo-panel,
    .historial-header {
        flex-direction: column;
        align-items: stretch;
    }

    .controles {
        flex-direction: column;
    }

    select {
        width: 100%;
    }

    .hero {
        height: 280px;
    }

    .hero-texto {
        left: 20px;
        bottom: 20px;
    }

    .hero-texto h2 {
        font-size: 24px;
    }

    .mediciones {
        grid-template-columns: 1fr;
    }

    .grafico {
        height: 300px;
    }

    /* CONTROLES DEL HISTORIAL EN CELULAR */

    .historial-controles {
        flex-direction: column;
        align-items: stretch;
    }

    .historial-controles select,
    .boton-exportar {
        width: 100%;
        text-align: center;
    }

}