:root {
    --bg-color: #f0e9ff;
    --text-color: #1f2937;
    --main-bg: rgba(255, 255, 255, 0.9);
    --btn-bg: #fdaaaa;
    --btn-hover-bg: #7c3aed;
    --card-shadow: rgba(0,0,0,0.1);
}

body.dark-theme {
    --bg-color: #1a202c;
    --text-color: #f3f4f6;
    --main-bg: rgba(45, 55, 72, 0.9);
    --btn-bg: #bd86fc;
    --btn-hover-bg: #a78bfa;
    --card-shadow: rgba(0,0,0,0.4);
}

body {
    font-family: 'Poppins', sans-serif;
    background: var(--bg-color);
    margin: 0;
    padding: 40px 20px;
    color: var(--text-color);
    transition: background 0.3s, color 0.3s;
}

.main-container {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    gap: 30px;
}

.sidebar {
    flex: 0 0 250px;
    background: var(--main-bg);
    border-radius: 20px;
    box-shadow: 0 10px 30px var(--card-shadow);
    padding: 30px;
}

.content-area {
    flex-grow: 1;
    background: var(--main-bg);
    border-radius: 20px;
    box-shadow: 0 10px 30px var(--card-shadow);
    padding: 30px;
}

h1 { 
    color: var(--btn-bg);
    font-weight: 600;
    margin-bottom: 5px;
    text-align: center;
}

p {
    color: var(--text-color);
    opacity: 0.8;
    text-align: center;
}

.section-title { 
    margin-top: 20px; 
    color: var(--text-color);
    font-weight: 600;
    font-size: 20px;
    border-bottom: 2px solid var(--btn-bg);
    padding-bottom: 5px;
    margin-bottom: 15px;
}

.btn-container { 
    display: flex;
    flex-direction: column;
    gap: 10px;
}

button {
    padding: 12px 24px;
    border: none;
    border-radius: 50px;
    background: var(--btn-bg);
    color: white;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s, background 0.3s;
    font-size: 16px;
    font-weight: 500;
    box-shadow: 0 4px 6px var(--card-shadow);
    text-align: left;
}

button:hover {
    background: var(--btn-hover-bg);
    transform: translateY(-2px);
    box-shadow: 0 6px 10px var(--card-shadow);
}

.videos { 
    display: flex; 
    flex-wrap: wrap; 
    justify-content: center; 
    gap: 20px;
    margin-top: 20px;
}

.video-card {
    width: 100%;
    max-width: 350px;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 8px 16px var(--card-shadow);
    background: var(--main-bg);
    transition: transform 0.3s;
}

.video-card:hover {
    transform: scale(1.03);
}

.video-card iframe { 
    width: 100%; 
    height: 200px; 
    display: block;
}

.video-card h3 {
    font-size: 18px;
    padding: 15px;
    color: var(--text-color);
    font-weight: 500;
    text-align: left;
}

#theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--btn-bg);
    color: white;
    box-shadow: 0 4px 8px var(--card-shadow);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    z-index: 100;
}

@media (max-width: 768px) {
    .main-container {
        flex-direction: column;
    }
    .sidebar {
        flex: none;
        width: 100%;
    }
}