@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@300;400;700&display=swap');

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

body {
    font-family: 'Poppins', sans-serif;
    background-color: #0d1117;
    color: #fff;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.chapter-container {
    width: 100%;
    max-width: 900px;
}

.back-link {
    display: inline-block;
    color: #7FDBFF;
    text-decoration: none;
    margin-bottom: 30px;
    font-size: 0.9em;
    transition: color 0.3s ease;
}
.back-link i { margin-right: 8px; }
.back-link:hover { color: #fff; }

.chapter-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
    margin-bottom: 20px;
}
.chapter-header h1 { font-size: 2.5em; }

/* MUDANÇA PRINCIPAL AQUI */
.video-player-wrapper {
    width: 100%;
    aspect-ratio: 16 / 9;
    border-radius: 16px;
    overflow: hidden;
    background-color: #000;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
}

/* O iframe gerado pelo JS deve preencher o wrapper */
.video-player-wrapper iframe {
    width: 100%;
    height: 100%;
    border: 0;
}

.description {
    text-align: center;
    margin-top: 20px;
    color: #a9c1d9;
    font-size: 0.9em;
}

.language-switcher { display: flex; gap: 10px; }
.lang-switch-btn { background-color: rgba(255, 255, 255, 0.1); color: #fff; border: 1px solid rgba(255, 255, 255, 0.2); padding: 8px 15px; border-radius: 5px; cursor: pointer; font-family: 'Poppins', sans-serif; transition: background-color 0.3s ease; }
.lang-switch-btn:hover { background-color: rgba(255, 255, 255, 0.2); }
.lang-switch-btn.active { background-color: #7FDBFF; color: #0d1117; font-weight: bold; }

@media (max-width: 600px) {
    .chapter-header { flex-direction: column; align-items: flex-start; }
    .chapter-header h1 { font-size: 2em; }
}