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

html {
    scroll-behavior: smooth;
}

body {
    font-family: Arial, Helvetica, sans-serif;
    line-height: 1.8;
    background: #f4f7fb;
    color: #172033;
}


/* =========================
   NAVIGATION
========================= */

.navbar {
    position: sticky;
    top: 0;
    z-index: 1000;

    display: flex;
    justify-content: space-between;
    align-items: center;

    padding: 18px 5%;

    background: rgba(4, 12, 27, 0.97);
    color: white;
}

.logo {
    font-size: 1.4rem;
    font-weight: bold;
    color: #63d5ff;
}

.menu {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;

    list-style: none;
}

.menu a {
    color: white;
    text-decoration: none;

    transition: 0.3s;
}

.menu a:hover {
    color: #63d5ff;
}


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

.hero {
    min-height: 90vh;

    display: flex;
    align-items: center;
    justify-content: center;

    text-align: center;

    background:
        linear-gradient(
            rgba(3, 10, 25, 0.68),
            rgba(3, 10, 25, 0.92)
        ),
        url("https://commons.wikimedia.org/wiki/Special:FilePath/Mariecurie.jpg");

    background-size: cover;
    background-position: center;
}

.hero-overlay {
    width: 100%;
    min-height: 90vh;

    display: flex;
    align-items: center;
    justify-content: center;
}

.hero-content {
    max-width: 900px;
    padding: 40px;
    color: white;
}

.sur-titre {
    color: #63d5ff;
    font-weight: bold;
    letter-spacing: 5px;
}

.hero h1 {
    font-size: clamp(4rem, 10vw, 8rem);
    line-height: 1.1;
    margin: 15px 0;
}

.hero h2 {
    font-size: clamp(1.5rem, 4vw, 2.8rem);
    font-weight: normal;
}

.hero p {
    margin: 25px auto;
    max-width: 700px;
    font-size: 1.2rem;
}

.btn {
    display: inline-block;

    padding: 14px 30px;

    border-radius: 50px;

    background: #63d5ff;
    color: #03111f;

    text-decoration: none;
    font-weight: bold;

    transition: 0.3s;
}

.btn:hover {
    transform: translateY(-4px);
    background: white;
}


/* =========================
   SECTIONS
========================= */

.section {
    padding: 90px 20px;
}

.container {
    max-width: 1100px;
    margin: auto;
}

.section h2 {
    margin-bottom: 30px;
    font-size: clamp(2rem, 5vw, 3rem);
}

.section p {
    margin-bottom: 20px;
    font-size: 1.08rem;
}

.numero {
    display: block;

    margin-bottom: 10px;

    color: #149bd3;

    font-weight: bold;
    letter-spacing: 4px;
}

.section-dark {
    background: #071225;
    color: white;
}

.section-blue {
    background:
        linear-gradient(
            135deg,
            #07182d,
            #145071
        );

    color: white;
}

.section-audio {
    background: #e8f8ff;
}


/* =========================
   CARDS
========================= */

.discoveries {
    display: grid;

    grid-template-columns:
        repeat(
            auto-fit,
            minmax(280px, 1fr)
        );

    gap: 30px;

    margin-top: 35px;
}

.card {
    padding: 35px;

    background: white;

    color: #172033;

    border-radius: 20px;

    box-shadow:
        0 15px 40px
        rgba(0, 0, 0, 0.12);

    transition: 0.3s;
}

.card:hover {
    transform: translateY(-7px);
}

.card-icon {
    font-size: 3rem;
}

.card h3 {
    margin: 15px 0;
}


/* =========================
   AUDIO
========================= */

.audio-controls {
    display: flex;
    flex-wrap: wrap;

    gap: 15px;

    margin-top: 30px;
}

.audio-controls button {
    border: none;

    padding: 14px 22px;

    border-radius: 30px;

    background: #0783b8;

    color: white;

    font-size: 1rem;

    cursor: pointer;

    transition: 0.3s;
}

.audio-controls button:hover {
    background: #045d82;

    transform: translateY(-2px);
}


/* =========================
   TIMELINE
========================= */

.timeline {
    position: relative;

    max-width: 850px;

    margin: 50px auto;
}

.timeline::before {
    content: "";

    position: absolute;

    top: 0;
    bottom: 0;

    left: 50%;

    width: 3px;

    background: #159bd3;

    transform: translateX(-50%);
}

.timeline-item {
    width: 50%;

    padding: 20px 40px;

    position: relative;
}

.timeline-item:nth-child(even) {
    margin-left: 50%;
}

.timeline-item:nth-child(odd) {
    text-align: right;
}

.timeline-item span {
    display: inline-block;

    padding: 7px 16px;

    border-radius: 30px;

    background: #159bd3;

    color: white;

    font-weight: bold;
}


/* =========================
   VIDEO
========================= */

.video-card {
    margin-top: 30px;

    padding: 30px;

    border-radius: 18px;

    background: rgba(255, 255, 255, 0.08);

    border: 1px solid
        rgba(255, 255, 255, 0.15);
}

.video-card h3 {
    margin-bottom: 12px;

    color: #63d5ff;
}

.media-link {
    display: inline-block;

    margin-top: 10px;

    padding: 12px 20px;

    border-radius: 30px;

    background: #63d5ff;

    color: #03111f;

    text-decoration: none;

    font-weight: bold;

    transition: 0.3s;
}

.media-link:hover {
    background: white;

    transform: translateY(-2px);
}


/* =========================
   GALERIE
========================= */

.gallery-list {
    margin: 25px 0 30px 25px;
}

.gallery {
    display: grid;

    grid-template-columns:
        repeat(
            auto-fit,
            minmax(220px, 1fr)
        );

    gap: 25px;

    margin-top: 40px;
}

.gallery-item {
    text-align: center;
}

.gallery-item img {
    width: 100%;
    height: 280px;

    object-fit: cover;

    border-radius: 15px;

    cursor: pointer;

    transition: 0.4s;
}

.gallery-item img:hover {
    transform: scale(1.04);

    filter: brightness(1.15);
}

.gallery-item p {
    margin: 10px 0 3px;
}

.gallery-item a {
    color: #0783b8;

    text-decoration: none;

    font-size: 0.9rem;
}


/* =========================
   LIGHTBOX
========================= */

#lightbox {
    position: fixed;

    inset: 0;

    display: none;

    align-items: center;
    justify-content: center;

    z-index: 9999;

    background: rgba(0, 0, 0, 0.97);
}

#imageGrande {
    max-width: 80%;
    max-height: 88%;

    object-fit: contain;

    border-radius: 10px;
}

.close {
    position: absolute;

    top: 15px;
    right: 30px;

    border: none;

    background: transparent;

    color: white;

    font-size: 4rem;

    cursor: pointer;

    z-index: 10001;
}

.fleche {
    position: absolute;

    top: 50%;

    transform: translateY(-50%);

    border: none;

    background: rgba(255, 255, 255, 0.1);

    color: white;

    width: 60px;
    height: 60px;

    border-radius: 50%;

    font-size: 2rem;

    cursor: pointer;

    z-index: 10001;

    transition: 0.3s;
}

.fleche:hover {
    background: #63d5ff;
    color: #03111f;
}

.gauche {
    left: 30px;
}

.droite {
    right: 30px;
}


/* =========================
   CONCLUSION
========================= */

.conclusion {
    text-align: center;

    color: white;

    background:
        radial-gradient(
            circle at center,
            #123d5d,
            #030914
        );
}

.phrase-finale {
    max-width: 850px;

    margin: 40px auto;

    color: #63d5ff;

    font-size: 1.4rem;
}


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

footer {
    padding: 30px;

    text-align: center;

    background: #02060d;

    color: #aaa;
}


/* =========================
   RESPONSIVE
========================= */

@media (max-width: 800px) {

    .navbar {
        flex-direction: column;

        gap: 15px;
    }

    .menu {
        justify-content: center;

        gap: 10px;
    }

    .hero {
        min-height: 80vh;
    }

    .hero-overlay {
        min-height: 80vh;
    }

    .timeline::before {
        left: 15px;
    }

    .timeline-item,
    .timeline-item:nth-child(even) {
        width: 100%;

        margin-left: 0;

        padding-left: 45px;

        text-align: left;
    }

    #imageGrande {
        max-width: 92%;
    }

    .fleche {
        width: 45px;
        height: 45px;

        font-size: 1.4rem;
    }

    .gauche {
        left: 10px;
    }

    .droite {
        right: 10px;
    }

}