```css
* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
    background: #eeeeee;
    color: #222;
}


/* =========================
   CAPÇALERA
   ========================= */

header {
    position: relative;
    background:
        linear-gradient(
            135deg,
            #172a63 0%,
            #172a63 42%,
            #b51f2a 42%,
            #b51f2a 58%,
            #172a63 58%,
            #172a63 100%
        );
    padding: 28px 20px;
    overflow: hidden;
}

.capcalera {
    max-width: 1150px;
    margin: auto;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 28px;
}

.escut {
    width: 105px;
    height: 105px;
    object-fit: contain;
    background: white;
    padding: 5px;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.35);
}

.titol {
    color: white;
}

.titol h1 {
    margin: 0;
    font-size: 42px;
    letter-spacing: 1px;
    text-shadow: 2px 2px 5px rgba(0,0,0,0.35);
}

.titol p {
    margin: 7px 0 0;
    font-size: 21px;
    letter-spacing: 2px;
}


/* =========================
   MENÚ
   ========================= */

nav {
    background: #101d45;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    box-shadow: 0 3px 8px rgba(0,0,0,0.25);
}

nav a {
    color: white;
    text-decoration: none;
    padding: 16px 20px;
    font-weight: bold;
    font-size: 16px;
    transition: 0.2s;
}

nav a:hover {
    background: #b51f2a;
}


/* =========================
   CONTINGUT PRINCIPAL
   ========================= */

main {
    max-width: 1150px;
    margin: 40px auto;
    padding: 0 20px;
}

.presentacio,
.efemerides {
    background: white;
    padding: 35px;
    margin-bottom: 30px;
    box-shadow: 0 3px 12px rgba(0,0,0,0.08);
}

main h2 {
    margin-top: 0;
    color: #172a63;
    font-size: 30px;
    border-bottom: 3px solid #b51f2a;
    padding-bottom: 10px;
}

main p {
    font-size: 17px;
    line-height: 1.7;
}

main a {
    color: #b51f2a;
    font-weight: bold;
}


/* =========================
   EFEMÈRIDES
   ========================= */

.efemerides-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 25px;
}

.efemeride {
    border: 1px solid #dddddd;
    background: #fafafa;
    padding: 25px;
}

.efemeride h3 {
    margin-top: 0;
    color: #172a63;
    font-size: 20px;
    border-bottom: 2px solid #b51f2a;
    padding-bottom: 10px;
}

.efemeride-item {
    background: white;
    padding: 15px;
    margin-top: 12px;
    border-left: 4px solid #b51f2a;
}

.efemeride-item strong {
    color: #172a63;
}

.efemeride-item p {
    margin: 5px 0 0;
    font-size: 15px;
}


/* =========================
   PEU
   ========================= */

footer {
    background: #101d45;
    color: white;
    text-align: center;
    padding: 20px;
    margin-top: 50px;
}

footer p {
    margin: 0;
}


/* =========================
   MÒBIL
   ========================= */

@media (max-width: 750px) {

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

    .titol h1 {
        font-size: 30px;
    }

    .titol p {
        font-size: 18px;
    }

    nav {
        flex-direction: column;
        text-align: center;
    }

    nav a {
        padding: 12px;
    }

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

    .presentacio,
    .efemerides {
        padding: 25px;
    }
}
```