/* ======= RESET ======= */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

/* ======= BODY ======= */
body {
    background-color: #0a0f1a; /* fond bleu-noir électronique */
    color: #d8f0ff;
    padding: 20px 40px;
}

/* ======= HEADER ======= */
header {
    margin-bottom: 30px;
    text-align: center;
}

h1 {
    color: #00e5b0; /* vert électronique clair */
    font-size: 2.5rem;
    margin-bottom: 15px;
}

/* ======= SUBMENU ======= */
nav.submenu ul {
    display: flex;
    justify-content: center;
    list-style: none;
    gap: 25px;
}

nav.submenu ul li a {
    color: #00e5b0;
    font-weight: bold;
    text-decoration: none;
    padding: 8px 15px;
    border-radius: 6px;
    transition: background 0.3s, color 0.3s;
}

nav.submenu ul li a:hover {
    background-color: #00aaff; /* bleu technique au survol */
    color: #0a0f1a;
}

/* ======= MAIN ======= */
main {
    background-color: #131c2a; /* panneau foncé type boîtier embarqué */
    padding: 20px;
    border-radius: 10px;
    border-left: 4px solid #00e5b0; /* bande verte électronique */
    box-shadow: 0 0 15px rgba(0, 229, 176, 0.08); /* ombre douce */
}

/* Texte principal */
p {
    font-size: 1rem;
    line-height: 1.6;
    text-align: center;
    color: #d8f0ff;
}

/* ======= RESPONSIVE ======= */
@media (max-width: 768px) {
    body { padding: 15px 20px; }
    h1 { font-size: 2rem; }
    nav.submenu ul { flex-direction: column; gap: 15px; }
}