body {
    font-family: 'Segoe UI', Arial, sans-serif;
    background: #f0f4fa;
    margin: 0;
    padding: 0;
}
.container {
    max-width: 700px;
    margin: 30px auto;
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 2px 12px rgba(0,0,0,0.08);
    padding: 32px 24px 24px 24px;
}
h1 {
    text-align: center;
    color: #2a4d8f;
}
nav {
    display: flex;
    justify-content: center;
    gap: 16px;
    margin-bottom: 32px;
}
nav button {
    background: #2a4d8f;
    color: #fff;
    border: none;
    border-radius: 6px;
    padding: 10px 18px;
    font-size: 1rem;
    cursor: pointer;
    transition: background 0.2s;
}
nav button:hover {
    background: #1b325b;
}
.activity-section {
    min-height: 300px;
}
.flashcard {
    background: #e3eafc;
    border-radius: 8px;
    padding: 32px 24px;
    text-align: center;
    margin-bottom: 16px;
    font-size: 1.5rem;
    color: #2a4d8f;
    box-shadow: 0 1px 4px rgba(42,77,143,0.08);
}
.flashcard img {
    max-width: 120px;
    margin-bottom: 12px;
}
.flashcard-audio {
    margin-top: 8px;
}
.matching-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
    margin-top: 24px;
}
.matching-item {
    background: #e3eafc;
    border-radius: 8px;
    padding: 18px;
    text-align: center;
    cursor: pointer;
    font-size: 1.1rem;
    transition: background 0.2s;
}
.matching-item.selected {
    background: #b6c9f1;
}
.matching-item.matched {
    background: #a2e3b2;
    color: #1b5e20;
}
.conversation-prompt {
    background: #f9fbe7;
    border-radius: 8px;
    padding: 24px 18px;
    font-size: 1.2rem;
    color: #4e5d6c;
    margin-bottom: 16px;
    box-shadow: 0 1px 4px rgba(42,77,143,0.06);
}