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

body {
    font-family: 'Roboto', sans-serif;
    background-color: rgba(255, 243, 222, 0.884);
    color: #333;
}

/* Ana Düzen (Layout) */
.video-container {
    display: flex;
    min-height: 100vh;
}

.back-link {
    margin-bottom: 20px;
    text-align: center;
    border-bottom: 1px solid orange;
    padding-bottom: 10px;
    border: 0caps;
    font-size: 18px;
    font-weight: bold;
}

/* Sol Menü / Sidebar */
.sidebar {
    width: 280px;
    background-color: rgba(245, 222, 183, 0.884);
    border-right: 1px solid #e9ecef;
    padding: 24px 16px;
    flex-shrink: 0;
}

.sidebar h2 {
    font-size: 1.25rem;
    margin-bottom: 20px;
    color: #1a1a1a;
    padding-bottom: 10px;
    border-bottom: 2px solid #f1f3f5;
}

.menu-list {
    list-style: none;
}

/* Video Butonları Stil Hazırlığı */
.video-btn {
    width: 100%;
    display: flex;
    align-items: center;
    padding: 12px 16px;
    background: transparent;
    background-color: #ff922b;
    border: none;
    border-bottom: 4px solid #ff0000;
    border-radius: 20px;
    font-size: 0.95rem;
    font-weight: 500;
    color: #ffffff;
    text-align: left;
    cursor: pointer;
    margin-bottom: 10px;

}

.video-btn:hover {
    background-color: #ff922b;
    color: #ffffff;
    transform: scale(1.02);
}

.video-btn.active {
    background-color: #ff4d00;
    border-bottom: 4px solid #ff922b;
    /* Tema renginize göre değiştirebilirsiniz */
}

/* Sağ / Orta Video Alanı */
.main-content {
    flex: 1;
    padding: 32px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
}

.player-wrapper {
    width: 100%;
    max-width: 900px;
    aspect-ratio: 16 / 9;
    background-color: #000;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
}

.player-wrapper iframe {
    width: 100%;
    height: 100%;
    border: 0;
}

/* Masaüstünde gizli mobil yardımcı elemanlar */
.playlist-toggle-btn,
.playlist-backdrop,
.drawer-header-mobile {
    display: none;
}

/* Mobil / Responsive Düzen (Bottom Sheet Drawer Tasarımı) */
@media (max-width: 768px) {
    .video-container {
        flex-direction: column;
        padding-bottom: 70px;
    }

    .main-content {
        padding: 16px 12px;
        width: 100%;
    }

    /* Sol Menüyü Mobil Açılır Çekmeceye (Bottom Sheet) Dönüştür */
    .sidebar {
        position: fixed;
        bottom: 0;
        left: 0;
        right: 0;
        width: 100%;
        max-height: 75vh;
        background-color: rgba(255, 245, 230, 0.98);
        border-radius: 24px 24px 0 0;
        box-shadow: 0 -10px 30px rgba(0, 0, 0, 0.25);
        z-index: 1000;
        transform: translateY(100%);
        transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        overflow-y: auto;
        padding: 16px 20px 30px;
        border-right: none;
        border-top: 1px solid rgba(255, 165, 0, 0.3);
    }

    .sidebar.open {
        transform: translateY(0);
    }

    /* Mobil Çekmece Başlığı ve Tutamaç */
    .drawer-header-mobile {
        display: flex;
        align-items: center;
        justify-content: center;
        margin-bottom: 16px;
        position: relative;
    }

    .sheet-handle {
        width: 44px;
        height: 5px;
        background-color: #d1d5db;
        border-radius: 10px;
    }

    .close-drawer-btn {
        position: absolute;
        right: 0;
        top: -4px;
        background: transparent;
        border: none;
        font-size: 1.4rem;
        color: #4b5563;
        cursor: pointer;
        padding: 4px 8px;
    }

    /* Ekran Karartma Arka Planı (Backdrop) */
    .playlist-backdrop {
        display: block;
        position: fixed;
        inset: 0;
        background-color: rgba(0, 0, 0, 0.55);
        backdrop-filter: blur(2px);
        z-index: 999;
        opacity: 0;
        pointer-events: none;
        transition: opacity 0.3s ease;
    }

    .playlist-backdrop.open {
        opacity: 1;
        pointer-events: auto;
    }

    /* Mobil Sağ Alt Yüzen "Ders Listesi" Butonu */
    .playlist-toggle-btn {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        gap: 10px;
        position: fixed;
        bottom: 20px;
        background: linear-gradient(135deg, #ff922b, #ff6b00);
        color: #ffffff;
        border: none;
        border-radius: 50px;
        padding: 14px 22px;
        font-size: 0.95rem;
        font-weight: 700;
        box-shadow: 0 8px 20px rgba(255, 107, 0, 0.4);
        z-index: 990;
        cursor: pointer;
        transition: transform 0.2s ease, box-shadow 0.2s ease;
    }

    .playlist-toggle-btn:hover {
        transform: translateY(-2px);
        box-shadow: 0 10px 24px rgba(255, 107, 0, 0.5);
    }

    .playlist-toggle-btn:active {
        transform: scale(0.95);
    }
}

.placeholder-box {
    width: 100%;
    height: 250%;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background-color: #1a1a1a;
    /* Oynatıcı arka planı */
    color: #ffffff;
    padding: 24px;
}

.placeholder-content h3 {
    font-size: 1.2rem;
    margin-bottom: 8px;
    color: #f8f9fa;
}

.placeholder-content p {
    font-size: 0.9rem;
    color: #adb5bd;
}