.layout {
    max-width: 1300px;
    margin: 24px auto 60px;
    padding: 0 16px;
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    align-items: start;
}

.panel.controls {
    flex: 1 1 420px;
    min-width: 320px;
}

.panel.preview {
    flex: 1 1 420px;
    min-width: 320px;
    display: flex;
    flex-direction: column;
    min-height: 400px;
}

.file-label {
    display: block;
    font-size: 14px;
    color: #4b4b4b;
    margin-bottom: 4px;
}

.caption {
    margin: 0 0 12px;
    font-size: 12px;
    color: #9a9a9a;
}

#source-input {
    width: 100%;
    min-height: 320px;
    font-family: 'Courier New', Courier, monospace;
    font-size: 12px;
    padding: 10px;
    border: 1px solid gainsboro;
    border-radius: 4px;
    background-color: white;
    color: #4b4b4b;
    resize: vertical;
}

.warning {
    margin-top: 12px;
    color: #8a5a00;
    background-color: whitesmoke;
    border-left: 4px solid #d99a00;
    border-radius: 4px;
    padding: 10px 14px;
    font-size: 14px;
}

.preview-heading {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
    margin-bottom: 4px;
}

.preview-heading h2 {
    margin: 0;
    font-size: 16px;
    font-family: "游ゴシック", 'ヒラギノ角ゴ ProN W3', sans-serif;
    color: #4b4b4b;
}

button#copy-btn {
    background-color: whitesmoke;
    color: #4b4b4b;
    border: 1px solid gainsboro;
    padding: 6px 14px;
    border-radius: 6px;
    font-size: 13px;
    cursor: pointer;
}

button#copy-btn:hover:not(:disabled) {
    background-color: #e6e6e6;
}

button#copy-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

#output {
    flex: 1;
    margin: 12px 0 0;
    padding: 12px;
    min-height: 320px;
    border: 1px solid gainsboro;
    border-radius: 4px;
    background-color: white;
    color: #4b4b4b;
    font-family: 'Courier New', Courier, monospace;
    font-size: 13px;
    white-space: pre-wrap;
    word-break: break-word;
    overflow: auto;
}