body {
    font-family: Arial, sans-serif;
    background: #1e1e2f;
    color: #f0f0f0;
    text-align: center;
}

header h1 {
    margin-bottom: 20px;
}

section {
    margin: 20px auto;
    padding: 10px;
    max-width: 500px;
    border: 1px solid #555;
    border-radius: 8px;
    background-color: #2b2b3f;
}

.xp-bar {
    width: 100%;
    height: 20px;
    background: #555;
    border-radius: 10px;
    margin: 10px 0;
}

#xpProgress {
    height: 100%;
    background: gold;
    width: 0%;
    border-radius: 10px;
    transition: width 0.5s;
}

button {
    margin-top: 10px;
    padding: 5px 15px;
    cursor: pointer;
}

ul {
    list-style: none;
    padding-left: 0;
}

li {
    margin: 5px 0;
    padding: 5px;
    border: 1px solid #888;
    border-radius: 5px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: #3a3a50;
}

.completed {
    text-decoration: line-through;
    opacity: 0.6;
}