body {
    background: linear-gradient(to bottom, #e0f7ff, #ffffff) no-repeat;
    background-size: cover;
    font-family: 'Yu Mincho', serif;
    color: #333;
    margin: 0;
    padding: 0;
    min-height: 100vh; /* ページ全体をカバー */
}

header {
    background-color: #b0c4de; /* 冬らしい淡いブルーグレー */
    padding: 20px 0;
    color: white;
    text-align: center;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
}

header h1 {
    font-size: 2.5rem;
    margin: 0;
    text-shadow: 1px 1px 3px rgba(0, 0, 0, 0.2);
}

.container {
    display: flex;
    justify-content: space-between;
    margin-top: 20px;
    width: 100%;
    max-width: 2000px;
    margin-left: auto;
    margin-right: auto;
    padding: 20px;
    background: rgba(255, 255, 255, 0.8);
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.left-container {
    width: 40%;
    margin-right: 20px;
}

.right-container {
    width: 55%;
    text-align: left;
}

h4 {
    margin-bottom: 10px;
    font-size: 1.2rem;
    font-weight: bold;
}

.button-group {
    display: flex;
    align-items: center;
    margin-right: 10px;
    margin-bottom: 20px;
}

.button-group div {
    margin-bottom: 20px;
}

.button-group button {
    margin-right: 10px;
    margin-bottom: 5px;
}

button {
    background-color: #a0d8ef;
    color: white;
    border: none;
    padding: 10px 20px;
    font-size: 1rem;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s ease;
    margin-bottom: 20px;
}

button:disabled {
    background-color: #c0c0c0;
    cursor: not-allowed;
}

button:hover:enabled {
    background-color: #5ebfd6;
}

input[type="file"] {
    margin: 20px 0;
}

#imageSizeInfo {
    color: #005f80;
    margin-bottom: 10px;
}

canvas {
    border: 1px solid #5ebfd6;
    border-radius: 10px;
    margin-top: 20px;
}