/* 基础样式 */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f5f5f5;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

header {
    background-color: #2c3e50;
    color: white;
    padding: 1rem 0;
    text-align: center;
    position: relative;
}

.back-btn {
    position: absolute;
    left: 20px;
    top: 50%;
    transform: translateY(-50%);
    color: white;
    text-decoration: none;
}

main {
    padding: 20px 0;
}

.card, .download-card {
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    padding: 20px;
    margin-bottom: 20px;
}

.btn {
    display: inline-block;
    background: #3498db;
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
    font-size: 16px;
    transition: background 0.3s;
}

.btn:hover {
    background: #2980b9;
}

.input-group {
    display: flex;
    margin: 20px 0;
}

.input-group input {
    flex: 1;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px 0 0 4px;
    font-size: 16px;
}

.input-group button {
    border-radius: 0 4px 4px 0;
}

.result-area {
    padding: 15px;
    background: #f8f9fa;
    border-radius: 4px;
    min-height: 50px;
}

footer {
    text-align: center;
    padding: 20px 0;
    color: #7f8c8d;
}

/* 响应式设计 */
@media (min-width: 768px) {
    main {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
        gap: 20px;
    }
}

@media (max-width: 767px) {
    .input-group {
        flex-direction: column;
    }

    .input-group input {
        border-radius: 4px;
        margin-bottom: 10px;
    }

    .input-group button {
        border-radius: 4px;
        width: 100%;
    }
}