body {
    font-family: "Kaiti", "STKaiti", "SimKai", serif; /* 使用楷体更有文化感 */
    background-color: #f0f4f8;
    background-image: linear-gradient(to bottom, #eef2f3, #8e9eab);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    color: #333;
}

.container {
    background: rgba(255, 255, 255, 0.95);
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    width: 90%;
    max-width: 500px;
    text-align: center;
    border: 2px solid #7f8c8d;
}

h1 { color: #c0392b; margin-bottom: 10px; }
h2 { color: #2c3e50; }

button {
    background-color: #2980b9;
    color: white;
    border: none;
    padding: 12px 25px;
    font-size: 18px;
    border-radius: 5px;
    cursor: pointer;
    margin-top: 20px;
    font-family: inherit;
    transition: background 0.3s;
}

button:hover { background-color: #1a5276; }

.screen { display: none; }
.screen.active { display: block; }

.options button {
    display: block;
    width: 100%;
    margin: 10px 0;
    background-color: #ecf0f1;
    color: #2c3e50;
    border: 1px solid #bdc3c7;
}

.options button:hover { background-color: #d5dbdb; }

.options button.correct { background-color: #27ae60; color: white; }
.options button.wrong { background-color: #c0392b; color: white; }

.hidden { display: none; }
.progress { font-size: 14px; color: #7f8c8d; margin-bottom: 15px; }