/* --- GLOBAL LAYOUT --- */
body {
    font-family: 'Segoe UI', Arial, sans-serif;
    background-color: #f4f7f9;
    margin: 0;
    padding-bottom: 80px; /* Space for the sticky blue menu */
}

#wrapper {
    max-width: 1050px; /* Limits width on desktop */
    margin: 0 auto;
    background: #fff;
    min-height: 100vh;
    box-shadow: 0 0 20px rgba(0,0,0,0.1);
}

/* --- HEADER --- */
.stem-header {
    background: #2c3e50;
    color: white;
    padding: 20px 40px;
    border-bottom: 4px solid #3498db;
}
.logo { font-size: 2rem; font-weight: bold; }
.logo span { color: #3498db; }

/* --- VIDEO SIZE FIX --- */
.video-container {
    max-width: 750px;
    margin: 30px auto;
    aspect-ratio: 16 / 9;
    background: #000;
    border-radius: 8px;
    overflow: hidden;
}
.video-container iframe { width: 100%; height: 100%; border: none; }

/* --- THE BLUE STICKY MENU --- */
.sticky-blue-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    background: #3498db; /* Blue background to match header */
    display: flex;
    justify-content: space-around;
    padding: 12px 0;
    z-index: 9999;
}

.sticky-blue-nav a {
    color: #ffffff;
    text-decoration: none;
    font-size: 0.8rem;
    font-weight: bold;
    text-align: center;
}

/* Desktop Centering for the Sticky Menu */
@media (min-width: 1050px) {
    .sticky-blue-nav {
        width: 450px;
        left: 50%;
        transform: translateX(-50%);
        border-radius: 15px 15px 0 0;
    }
}
.teacher-corner {
    background-color: #fff9eb; /* Light, warm background */
    border-left: 6px solid #3498db; /* Distinct Blue border (Header Color) */
    padding: 25px;
    margin: 35px 0;
    border-radius: 4px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.teacher-corner h3 {
    margin-top: 0;
    color: #2c3e50;
    font-size: 1.4rem;
}
/* --- CONTENT AREA SPACING --- */
.content-area {
    padding: 10px 20px; /* Top/Bottom: 30px | Left/Right: 50px */
    box-sizing: border-box; /* Ensures padding doesn't break layout width */
}

/* Ensure the wrapper handles content correctly */
#wrapper {
    max-width: 1050px;
    margin: 0 auto;
    background: #fff;
    overflow-x: hidden; /* Prevents horizontal scroll on small screens */
}
/* --- QUIZ BOX STYLING --- */
.quiz-container {
    background-color: #f0f7ff; /* Very light blue distinct from Teacher Tips */
    border: 1px solid #d1e3f8;
    border-radius: 12px;
    padding: 30px;
    margin: 40px 0;
    box-shadow: 0 4px 15px rgba(0,0,0,0.05);
}

.quiz-container h2 {
    margin-top: 0;
    color: #2c3e50;
    border-bottom: 2px solid #3498db;
    padding-bottom: 10px;
    margin-bottom: 20px;
}

.quiz-item {
    background: #ffffff; /* White background for the actual questions */
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 15px;
    border: 1px solid #e1e8ed;
}