body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background: #f5f6fa;
    margin: 0;
    padding: 0;
}

.container {
    max-width: 720px;
    margin: 40px auto;
    background: #ffffff;
    padding: 24px 28px 32px;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.06);
}

h1 {
    margin-top: 0;
    font-size: 24px;
    text-align: center;
}

.desc {
    font-size: 14px;
    color: #555;
    line-height: 1.6;
}

fieldset {
    border: 1px solid #ddd;
    border-radius: 8px;
    margin-top: 18px;
    padding: 16px 18px 12px;
}

legend {
    padding: 0 8px;
    font-size: 14px;
    font-weight: 600;
}

label {
    display: block;
    margin-top: 10px;
    font-size: 14px;
}

input[type="text"],
input[type="file"] {
    display: block;
    margin-top: 6px;
    padding: 6px 8px;
    width: 100%;
    max-width: 380px;
    border-radius: 6px;
    border: 1px solid #ccc;
    font-size: 14px;
    box-sizing: border-box;
}

.mode {
    margin-top: 6px;
    font-size: 14px;
}

.mode label {
    display: inline-block;
    margin-right: 16px;
}

.options {
    margin-top: 10px;
    font-size: 14px;
}

.hidden {
    display: none;
}

.formula {
    background: #f7f7ff;
    border-radius: 6px;
    padding: 6px 8px;
    font-size: 13px;
    margin: 8px 0;
}

.tip {
    font-size: 12px;
    color: #888;
}

code {
    background: #f0f0f0;
    padding: 1px 4px;
    border-radius: 4px;
}

.submit-btn {
    margin-top: 20px;
    width: 100%;
    padding: 10px 16px;
    border-radius: 8px;
    border: none;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    background: #4c6fff;
    color: #ffffff;
}

.submit-btn:hover {
    background: #3c59d4;
}

.footer {
    margin-top: 16px;
    font-size: 12px;
    text-align: center;
    color: #888;
}