:root {
    /* デフォルト (ダークテーマ) */
    --bg-gradient: linear-gradient(180deg, #0d1016 0%, #121722 100%);
    --panel-bg: rgba(23, 26, 33, 0.92);
    --bg: #0f1115;
    --panel: #171a21;
    --panel-2: #1f2430;
    --text: #eef2f7;
    --muted: #a7b0c0;
    --accent: #56b6c2;
    --border: #2c3442;
    --success: #7ccf8a;
    --danger: #ff7a90;
    --radius: 14px;
    --shadow: 0 12px 32px rgba(0, 0, 0, 0.28);
    --btn-text: #081014;
}

body.light-theme {
    /* ライトテーマ */
    --bg-gradient: linear-gradient(180deg, #f4f7fa 0%, #e9ecef 100%);
    --panel-bg: rgba(255, 255, 255, 0.92);
    --bg: #f4f7fa;
    --panel: #ffffff;
    --panel-2: #e2e6eb;
    --text: #2c3440;
    --muted: #6c757d;
    --accent: #3a97a5; /* 視認性のため少し濃い色に変更 */
    --border: #d2d6db;
    --success: #28a745;
    --danger: #dc3545;
    --shadow: 0 12px 32px rgba(0, 0, 0, 0.08);
    --btn-text: #ffffff;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic UI", "Yu Gothic", sans-serif;
    background: var(--bg-gradient);
    color: var(--text);
    min-height: 100vh;
    transition: background 0.3s ease, color 0.3s ease;
}

.wrap {
    max-width: 1280px;
    margin: 0 auto;
    padding: 24px;
}

h1 {
    margin: 0 0 8px;
    font-size: clamp(1.8rem, 2.6vw, 2.6rem);
}

.lead {
    margin: 0 0 24px;
    color: var(--muted);
    line-height: 1.7;
}

.toolbar {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 8px;
}

button {
    border: 1px solid var(--border);
    background: var(--panel-2);
    color: var(--text);
    padding: 10px 16px;
    border-radius: 999px;
    cursor: pointer;
    font-size: 0.95rem;
    transition: background 0.3s, color 0.3s, border-color 0.3s;
}

button.primary {
    background: var(--accent);
    color: var(--btn-text);
    border-color: transparent;
    font-weight: 700;
}

button:hover {
    filter: brightness(1.06);
}

.options {
    margin-bottom: 16px;
    color: var(--muted);
    font-size: 0.9rem;
}

.options label {
    margin-right: 16px;
    cursor: pointer;
}

.grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.panel {
    background: var(--panel-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: background 0.3s, border-color 0.3s, box-shadow 0.3s;
}

.panel-header {
    padding: 14px 16px;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
}

.panel-header h2 {
    margin: 0;
    font-size: 1rem;
}

.status {
    font-size: 0.88rem;
    color: var(--muted);
}

textarea {
    width: 100%;
    min-height: 68vh;
    resize: vertical;
    border: 0;
    outline: 0;
    padding: 18px;
    background: transparent;
    color: var(--text);
    font-size: 1rem;
    line-height: 1.9;
    font-family: "Hiragino Mincho ProN", "Yu Mincho", "MS PMincho", serif;
    transition: color 0.3s;
}

.help {
    margin-top: 18px;
    color: var(--muted);
    line-height: 1.8;
    font-size: 0.95rem;
}

.ok { color: var(--success); }
.err { color: var(--danger); }

@media (max-width: 900px) {
    .grid { grid-template-columns: 1fr; }
    textarea { min-height: 40vh; }
}