body {
    font-family: Arial, sans-serif;
    margin: 0;
    min-height: 100vh;
    transition: background-color 0.3s, color 0.3s;
}
body.light-mode {
    background-color: #f4f7fa;
    color: #333;
}
body.dark-mode {
    background-color: #2c3e50;
    color: #ecf0f1;
}
nav {
    background-color: #1e90ff;
    padding: 15px;
    text-align: center;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}
nav a, nav button {
    color: white;
    margin: 0 20px;
    text-decoration: none;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 16px;
}
nav a:hover, nav button:hover {
    text-decoration: underline;
}
.container {
    background: white;
    padding: 25px;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.05);
    width: 450px;
    text-align: center;
    margin: 30px auto;
}
body.dark-mode .container {
    background: #34495e;
}
h1, h2 {
    color: #333;
}
body.dark-mode h1, body.dark-mode h2 {
    color: #ecf0f1;
}
input, button, select {
    width: 100%;
    padding: 12px;
    margin: 8px 0;
    box-sizing: border-box;
    border: 1px solid #ccc;
    border-radius: 5px;
}
body.dark-mode input, body.dark-mode select {
    background: #ecf0f1;
    color: #2c3e50;
}
button {
    background-color: #1e90ff; /* Default blue */
    color: white;
    border: none;
    cursor: pointer;
    transition: background-color 0.3s;
    display: block; /* Ensure visibility */
}
button:hover {
    background-color: #187bcd; /* Darker blue on hover */
}
#save-quiz {
    background-color: #1e90ff; /* Explicitly set for Save Quiz */
    color: white;
    margin-top: 20px; /* Spacing */
}
#save-quiz:hover {
    background-color: #187bcd; /* Consistent hover state */
}
.submit-btn {
    display: block;
    margin-top: 20px;
    width: 100%;
    background-color: #27ae60; /* Green for Submit Quiz */
}
.submit-btn:hover {
    background-color: #219653; /* Darker green on hover */
}
.question {
    margin: 25px 0;
    padding: 15px;
    border: 1px solid #e0e0e0;
    border-radius: 5px;
    text-align: left;
    background-color: #fafafa;
}
body.dark-mode .question {
    background-color: #3d566e;
    border-color: #5d7a94;
}
label {
    display: block;
    margin: 12px 0 6px;
    text-align: left;
    font-weight: bold;
}
.quiz-item, .leaderboard-item {
    margin: 20px 0;
    padding: 15px;
    border: 1px solid #e0e0e0;
    border-radius: 5px;
    background-color: #fff;
}
body.dark-mode .quiz-item, body.dark-mode .leaderboard-item {
    background-color: #34495e;
    border-color: #5d7a94;
}
.quiz-item button {
    width: auto;
    padding: 8px 15px;
    margin-top: 10px;
}
#quiz-container {
    text-align: left;
}
#analytics p {
    margin: 8px 0;
    font-size: 14px;
}
#timer {
    font-weight: bold;
    margin: 10px 0;
}
.progress-bar {
    width: 100%;
    height: 20px;
    background-color: #e0e0e0;
    border-radius: 10px;
    margin: 10px 0;
    overflow: hidden;
}
#progress {
    height: 100%;
    background-color: #1e90ff;
    width: 0;
    transition: width 0.3s ease;
}
body.dark-mode .progress-bar {
    background-color: #5d7a94;
}
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}
.container, .quiz-item, .leaderboard-item, #score {
    animation: fadeIn 0.5s ease-in;
}