.tool-container {
    background: #fff;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    border: 1px solid #eee;
}

.main-input {
    width: 100%;
    height: 350px; /* JSONは見やすいよう少し高めに */
    padding: 15px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-family: 'Courier New', Courier, monospace;
    font-size: 0.95rem;
    box-sizing: border-box;
    margin-bottom: 15px;
}

.control-panel {
    display: flex;
    gap: 20px;
    margin-bottom: 15px;
    flex-wrap: wrap;
    align-items: flex-end;
}

.btn-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.btn-label {
    font-size: 0.75rem;
    font-weight: bold;
    color: #999;
    text-transform: uppercase;
}

.btn {
    padding: 10px 18px;
    background: #333f47;
    color: #fff;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-weight: bold;
    font-size: 0.9rem;
}

.btn-secondary { background: #55acee; }
.btn-accent { background: #27ae60; } /* エスケープ系は色を変えて視認性アップ */
.btn-clear { background: #999; margin-left: auto; align-self: flex-end; }

.error-msg {
    color: #e74c3c;
    font-size: 0.9rem;
    margin-top: 15px;
    min-height: 1.2em;
}