body {
    font-family: Arial, sans-serif;
    margin: 20px;
}

h1, h2 {
    color: #333;
}

#intro-page, #d2-test-container, #stroop-test-container, #results-page, #stroop-transition {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin: auto;
}

.buttons-container {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 10px;
    margin-top: 20px;
}
#buttons-container{
    display: flex;
    justify-content: center;
}
button {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
}

.stroop-box {
    margin: auto;
    font-size: 2em;
    font-weight: bold;
    padding: 20px;
    border: 2px solid #333;
    text-align: center;
    width: 150px;
    height: 100px;
}

.selected-correct {
    background-color: red;
}

.selected-incorrect {
    background-color: darkred;
}

.RoodKnop{
    background-color: red;
}

.GroenKnop{
    background-color: green;
}
.BlauwKnop{
    background-color: blue;
}
.GeelKnop{
    background-color: yellow;
}