:root {
    --background-color: #f0f0f0; /* ライトグレー */
    --container-bg-color: #ffffff;
    --text-color: #333333;
    --secondary-text-color: #757575;
    --accent-color: #d32f2f; /* 落ち着いた赤 */
    --border-color: #e0e0e0;
    --drop-zone-bg-color: #fafafa;
    --drop-zone-border-color: #d9d9d9;
    --shadow-color: rgba(0, 0, 0, 0.08);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
    box-sizing: border-box;
}

.container {
    width: 100%;
    max-width: 700px;
    background-color: var(--container-bg-color);
    border-radius: 8px;
    box-shadow: 0 4px 16px var(--shadow-color);
    padding: 30px 40px;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

header h1 {
    margin: 0 0 8px 0;
    font-size: 1.8em;
    font-weight: 600;
}

header p {
    margin: 0;
    color: var(--secondary-text-color);
    font-size: 1.1em;
}

#drop-zone {
    background-color: var(--drop-zone-bg-color);
    border: 2px dashed var(--drop-zone-border-color);
    border-radius: 8px;
    padding: 40px;
    text-align: center;
    cursor: pointer;
    transition: border-color 0.2s, background-color 0.2s;
}

#drop-zone p {
    color: var(--secondary-text-color);
    margin: 0;
    font-size: 1.1em;
}

#drop-zone.dragover {
    background-color: #f5f5f5;
    border-color: var(--accent-color);
}

#meta-data-container {
    margin-top: 30px;
}

#meta-data-container h2 {
    font-size: 1.4em;
    color: var(--text-color);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 10px;
    margin-bottom: 20px;
}

#meta-data-container pre {
    background-color: #f7f7f7;
    padding: 15px;
    border-radius: 6px;
    white-space: pre-wrap;
    word-break: break-all;
    font-size: 0.95em;
    line-height: 1.6;
    color: #212121;
    max-height: 350px;
    overflow-y: auto;
}