* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    margin: 0;
    padding: 20px 0;
    color: #333;
}
.page-wrapper {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
}
#container {
    width: 100%;
    background: #ffffff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
    margin-bottom: 30px;
}
h1 {
    text-align: center;
    color: #2c3e50;
    margin-top: 0;
    margin-bottom: 10px;
    font-size: 28px;
}
.subtitle {
    text-align: center;
    color: #7f8c8d;
    font-size: 14px;
    margin-bottom: 25px;
}
.form-group { margin-bottom: 20px; }
label {
    display: block;
    margin-bottom: 8px;
    font-weight: bold;
    font-size: 16px;
}
input[type="file"], select {
    width: 100%;
    padding: 12px;
    border: 1px solid #ccc;
    border-radius: 8px;
    box-sizing: border-box;
    font-size: 16px;
    background-color: #fafafa;
}
input[type="file"] { padding: 9px; }
button {
    width: 100%;
    padding: 14px;
    background-color: #3498db;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 18px;
    font-weight: bold;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}
button:hover {
    background-color: #2980b9;
    box-shadow: 0 4px 8px rgba(52, 152, 219, 0.3);
}
button:disabled {
    background-color: #bdc3c7;
    cursor: not-allowed;
    box-shadow: none;
}
#status {
    text-align: center;
    margin-top: 20px;
    font-size: 15px;
    min-height: 1.2em;
}
#status.success { color: #2ecc71; }
#status.error { color: #e74c3c; }
#status.processing { color: #3498db; }

/* --- 预览区域 --- */
#previewArea {
    display: none; /* 默认隐藏 */
    flex-direction: column;
    gap: 20px;
    margin-top: 25px;
    border-top: 1px dashed #ccc;
    padding-top: 25px;
}
@media (min-width: 500px) {
    #previewArea {
        flex-direction: row;
        justify-content: space-between;
        align-items: flex-start;
    }
}
.preview-box {
    flex: 1;
    text-align: center;
    min-width: 0;
}

/* --- CSS 修改点 --- */
/* 默认隐藏 "转换后" 的面板 */
#convertedBox {
    display: none;
}
/* --- CSS 修改结束 --- */

h3 {
    margin-top: 0;
    color: #555;
    font-weight: 600;
}
img {
    max-width: 100%;
    height: auto;
    max-height: 250px;
    min-height: 150px;
    border: 2px solid #ecf0f1;
    border-radius: 8px;
    background: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20"><path fill="%23eee" d="M0 0h10v10H0zM10 10h10v10H10z"/></svg>');
    background-size: 10px 10px;
    background-color: #f7f7f7;
    display: block;
    margin: 0 auto;
}
#downloadLink {
    display: none;
    margin-top: 15px;
    padding: 12px;
    background-color: #2ecc71;
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: bold;
    transition: background-color 0.3s ease;
    text-align: center;
}
#downloadLink:hover {
    background-color: #27ae60;
}

/* 功能介绍区域 */
.info-section {
    background: #ffffff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
    margin-bottom: 30px;
}
.info-section h2 {
    color: #2c3e50;
    margin-bottom: 20px;
    font-size: 22px;
    border-bottom: 3px solid #3498db;
    padding-bottom: 10px;
}
.formats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
    margin-top: 20px;
}
.format-item {
    background: #f8f9fa;
    padding: 15px;
    border-radius: 8px;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.format-item:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}
.format-item strong {
    color: #2c3e50;
    font-size: 16px;
}
.format-item p {
    color: #7f8c8d;
    font-size: 13px;
    margin-top: 5px;
}
.advantages-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-top: 20px;
}
.advantage-item {
    text-align: center;
    padding: 20px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 10px;
    color: white;
    transition: transform 0.3s ease;
}
.advantage-item:hover {
    transform: scale(1.05);
}
.advantage-icon {
    font-size: 40px;
    margin-bottom: 10px;
}
.advantage-item h3 {
    font-size: 18px;
    margin-bottom: 10px;
    color: white;
}
.advantage-item p {
    font-size: 14px;
    opacity: 0.95;
    color: white;
}

/* 友情链接 */
.footer-section {
    background: #ffffff;
    padding: 25px 30px;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
    margin-bottom: 30px;
}
.footer-section h3 {
    color: #2c3e50;
    margin-bottom: 15px;
    font-size: 18px;
}
.links-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
}
.link-item {
    padding: 8px 16px;
    background: #ecf0f1;
    border-radius: 20px;
    text-decoration: none;
    color: #34495e;
    font-size: 14px;
    transition: all 0.3s ease;
    display: inline-block;
}
.link-item:hover {
    background: #3498db;
    color: white;
    transform: translateY(-2px);
}
.copyright {
    text-align: center;
    color: white;
    font-size: 13px;
    padding: 20px;
    opacity: 0.9;
}