body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f7f9;
    color: #333;
}

#app {
    width: 95%;
    max-width: 1200px;
    margin: 20px auto;
    background-color: #fff;
    border-radius: 8px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

header {
    background: linear-gradient(45deg, #007bff, #0056b3);
    color: #fff;
    padding: 20px 25px;
    text-align: center;
    border-top-left-radius: 8px;
    border-top-right-radius: 8px;
}
header h1 { margin: 0; font-size: 1.8rem; }
header p { margin: 5px 0 0; opacity: 0.9; }

#mode-selector {
    display: flex;
    justify-content: center;
    padding: 15px;
    background-color: #f8f9fa;
    border-bottom: 1px solid #dee2e6;
}

#mode-selector button {
    font-size: 1rem;
    padding: 10px 20px;
    margin: 0 5px;
    border: 1px solid #dee2e6;
    border-radius: 5px;
    cursor: pointer;
    background-color: #fff;
    color: #007bff;
    transition: all 0.3s ease;
    font-weight: 500;
}
#mode-selector button:hover { background-color: #e9ecef; }
#mode-selector button.active {
    background-color: #007bff;
    color: #fff;
    border-color: #007bff;
}

#workspace { padding: 20px; }

/* --- ▼▼▼ 新しいスタイル ▼▼▼ --- */
#view-controls {
    margin-bottom: 20px;
}
.view-panel {
    display: none;
    border: 1px solid #007bff;
    background-color: #f0f8ff;
    border-radius: 5px;
    padding: 15px;
}
.view-panel.active {
    display: block;
}
.view-panel fieldset {
    border: none;
    padding: 0;
    margin: 0;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}
.view-panel legend {
    font-weight: bold;
    color: #0056b3;
    padding: 0;
    margin-bottom: 10px;
    width: 100%;
    font-size: 1.1em;
}
.range-inputs {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}
.range-inputs label {
    display: flex;
    align-items: center;
    gap: 5px;
    font-size: 0.95em;
}
.range-inputs input[type="number"] {
    width: 80px;
    padding: 6px 8px;
    border: 1px solid #ccc;
    border-radius: 4px;
}
.range-inputs input[type="number"]:disabled {
    background-color: #e9ecef;
    opacity: 0.7;
}
.autoscale-label {
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 5px;
}
/* --- ▲▲▲ ここまで ▲▲▲ --- */

#panel-container {
    /* このコンテナは削除しても良いですが、構造の互換性のため残します */
}

.control-panel {
    display: none;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-top: 20px; /* view-controlsとの間にマージンを追加 */
}
.control-panel.active { display: grid; }

.input-section {
    border: 1px solid #e0e0e0;
    border-radius: 5px;
    padding: 15px;
    background-color: #fdfdfd;
}
.input-section h3 {
    margin-top: 0;
    font-size: 1.1rem;
    color: #333;
    border-bottom: 1px solid #e9ecef;
    padding-bottom: 10px;
    margin-bottom: 15px;
}

.item-list {
    max-height: 200px; /* 少し高さを調整 */
    overflow-y: auto;
    padding: 5px;
    background-color: #f8f9fa;
    border-radius: 4px;
    border: 1px solid #e9ecef;
}

.input-item {
    display: flex;
    align-items: center;
    margin-bottom: 8px;
    background: white;
    padding: 5px;
    border-radius: 4px;
    border: 1px solid #ddd;
}
.input-item input {
    flex-grow: 1;
    font-size: 1rem;
    padding: 8px;
    border: 1px solid #ccc;
    border-radius: 4px;
}
.input-item .delete-btn {
    background: #dc3545;
    color: white;
    border: none;
    border-radius: 50%;
    width: 24px;
    height: 24px;
    font-weight: bold;
    cursor: pointer;
    margin-left: 8px;
    flex-shrink: 0;
    line-height: 24px;
    text-align: center;
}

.add-btn {
    margin-top: 10px;
    padding: 8px 12px;
    border: 1px solid #007bff;
    background: #e7f1ff;
    color: #007bff;
    cursor: pointer;
    border-radius: 4px;
    width: 100%;
}
.add-btn:hover { background: #d0e3ff; }

.formula-item-3d {
    display: block; padding: 10px;
}
.formula-item-3d .main-formula {
    display: flex; align-items: center; width: 100%;
}
.formula-item-3d .main-formula span {
    margin-right: 5px; font-weight: bold;
}
.formula-item-3d .options-panel {
    display: none; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 10px; padding: 10px; border-top: 1px dashed #ccc;
}
.formula-item-3d .options-panel.visible { display: grid; }
.formula-item-3d .options-panel fieldset {
    border: 1px solid #ddd;
    border-radius: 4px;
    padding: 8px;
}
.formula-item-3d .options-panel legend {
    font-size: 0.9em;
    padding: 0 5px;
    color: #555;
}
.formula-item-3d .options-panel input {
    width: 100%;
    box-sizing: border-box;
    margin-top: 5px;
    font-size: 0.9rem;
}

.formula-item-3d .options-panel .axis-inputs {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 5px;
}

.toggle-options-btn {
    background: #6c757d; color: white; border: none; border-radius: 4px; padding: 4px 8px; font-size: 0.8em; cursor: pointer; margin: 0 5px;
}

#action-bar {
    text-align: center; margin-top: 20px;
}
#draw-btn {
    font-size: 1.2rem; padding: 12px 30px; border: none; border-radius: 5px; cursor: pointer; background-color: #28a745; color: white; font-weight: bold; transition: background-color 0.3s ease;
}
#draw-btn:hover { background-color: #218838; }

#plot-container {
    position: relative; width: 100%; height: 600px; border: 1px solid #ddd; border-radius: 5px; margin-top: 20px;
}
#plot { width: 100%; height: 100%; }

#error-message {
    position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); background-color: rgba(255, 0, 0, 0.85); color: white; padding: 20px; border-radius: 8px; z-index: 10; text-align: center; max-width: 80%;
}
.hidden { display: none; }

footer {
    text-align: center; padding: 15px; font-size: 0.9rem; color: #777; background-color: #f8f9fa; border-bottom-left-radius: 8px; border-bottom-right-radius: 8px;
}

@media (max-width: 992px) {
    .control-panel, .formula-item-3d .options-panel { grid-template-columns: 1fr; }
    .view-panel fieldset { flex-direction: column; align-items: flex-start; }
    .range-inputs { flex-direction: column; width: 100%; }
    .autoscale-label { margin-top: 10px; }
}