body {
    font-family: sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding-top: 50px;
    background-color: #ffffff;
    margin: 0;
}

#main-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
}

/* 見出し */
h2 {
    text-align: center;
    font-size: 1.6em;
    margin-bottom: 10px;
}

/* pタグ：暗証番号のメッセージ */
.sub-message {
    font-size: 1.1em;
    color: #555;
    font-weight: bold;
    margin: 5px 0;
}

/* pタグ：許可ファイル形式の表示 */
.file-info {
    font-size: 0.9em;
    color: #888;
    margin-bottom: 20px;
}

/* ドロップエリア */
#drop-area {
    border: 3px dashed #007bff;
    padding: 60px 20px;
    text-align: center;
    background-color: #f0f8ff;
    margin: 10px auto;
    width: 90%;
    max-width: 500px;
    border-radius: 15px;
    color: #007bff;
    font-weight: bold;
    font-size: 1.2em;
    cursor: pointer;
    transition: all 0.3s;
    box-sizing: border-box;
}

#drop-area:hover {
    background-color: #e1f0ff;
}

#drop-area.dragover {
    background-color: #d0e7ff;
    border-color: #0056b3;
    transform: scale(1.03);
}

/* 戻るボタン */
.btn-back {
    padding: 10px 20px;
    background-color: #f0f8ff;
    border: 2px solid #007bff;
    color: #007bff;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    transition: 0.3s;
}

.btn-back:hover {
    background-color: #007bff;
    color: #ffffff;
}

/* アップロードボタン */
.upload-btn-container {
    cursor: pointer;
    margin-bottom: 25px;
}

.upload-btn {
    display: inline-block;
    padding: 8px 18px;
    background-color: #6c757d; /* 控えめなグレー */
    color: #fff !important;
    text-decoration: none;
    border-radius: 5px;
    font-size: 0.85em;
    transition: 0.3s;
}

.upload-btn:hover {
    background-color: #495057;
}

/* スライドコメント */
.slide-info {
  width: 90%;
  max-width: 500px;
  margin-top: 32px;
  margin-bottom: 32px;
}

.slide-info-tr {
  display: block;
  position: relative;
  width: 100%;
}

.slide-info-label {
  width: 40%;
  max-width: 100px;
  display: inline-block;
  position: relative;
  text-align: right;
}

.slide-info-input {
  width: 60%;
  max-width: 400px;
  display: inline-block;
  position: relative;
  text-align: left;
}

.info-input {
  width: 100%;
}