:root {
    /* ライトモード (デフォルト) */
    --primary: #27ae60;
    --accent: #2980b9;
    --bg: #f0f2f5;
    --container-bg: #ffffff;
    --card-bg: #f8f9fa;
    --text: #2c3e50;
    --text-muted: #7f8c8d;
    --border: #dddddd;
    --input-bg: #ffffff;
    --formula-bg: #eeeeee;
    --error: #e74c3c;
}

@media (prefers-color-scheme: dark) {
    :root {
        /* ダークモード */
        --bg: #121212;
        --container-bg: #1e1e1e;
        --card-bg: #2d2d2d;
        --text: #e0e0e0;
        --text-muted: #b0b0b0;
        --border: #444444;
        --input-bg: #252525;
        --formula-bg: #2d2d2d;
        --error: #ff6b6b;
    }
}

body {
    font-family: 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg);
    color: var(--text);
    display: flex;
    justify-content: center;
    padding: 20px;
    margin: 0;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    background: var(--container-bg);
    padding: 25px;
    border-radius: 16px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
    width: 100%;
    max-width: 700px;
}

h1 {
    text-align: center;
    font-size: 1.4rem;
    margin-bottom: 25px;
}

.input-card {
    background: var(--card-bg);
    padding: 20px;
    border-radius: 12px;
    margin-bottom: 20px;
}

.field {
    margin-bottom: 15px;
}

label {
    display: block;
    font-weight: bold;
    margin-bottom: 5px;
    font-size: 0.9rem;
}

input[type="number"] {
    width: 100%;
    padding: 10px;
    border: 2px solid var(--border);
    border-radius: 8px;
    box-sizing: border-box;
    font-size: 1rem;
    background-color: var(--input-bg);
    color: var(--text);
}

.checkbox-field {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: bold;
    cursor: pointer;
    user-select: none;
    margin-top: 10px;
}

button {
    width: 100%;
    padding: 15px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: filter 0.2s;
}

button:hover {
    filter: brightness(1.1);
}

button:disabled {
    background: #777;
    cursor: not-allowed;
}

.error-display {
    color: var(--error);
    font-size: 0.85rem;
    font-weight: bold;
    margin-top: 10px;
    min-height: 1.2em;
    text-align: center;
}

.warning-text {
    color: var(--text-muted);
    font-size: 0.75rem;
    text-align: center;
    margin-top: 10px;
    line-height: 1.4;
}

.result-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
    margin-top: 25px;
    display: none;
}

.result-card {
    background: var(--container-bg);
    border: 2px solid var(--border);
    padding: 15px;
    border-radius: 10px;
}

.result-card.best { border-color: var(--primary); }
.result-card.over { border-color: var(--accent); }

.card-title {
    font-size: 0.8rem;
    font-weight: bold;
    margin-bottom: 10px;
    display: block;
    color: var(--text-muted);
}

.res-val {
    font-size: 1.4rem;
    font-weight: bold;
    display: block;
    margin-bottom: 5px;
}

.best .res-val { color: var(--primary); }
.over .res-val { color: var(--accent); }

.error-text {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.details {
    font-size: 0.85rem;
    line-height: 1.5;
    border-top: 1px solid var(--border);
    padding-top: 8px;
    margin-top: 8px;
}

.status {
    font-size: 0.8rem;
    color: var(--text-muted);
    text-align: center;
    margin-top: 5px;
    min-height: 1.2em;
}

.formula-info {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 15px;
    background: var(--formula-bg);
    padding: 10px;
    border-radius: 6px;
}

.footer {
    margin-top: 30px;
    padding-top: 15px;
    border-top: 1px solid var(--border);
    text-align: center;
    font-size: 0.75rem;
    color: var(--text-muted);
}

.footer a {
    color: var(--accent);
    text-decoration: none;
    font-weight: bold;
}

.footer a:hover {
    text-decoration: underline;
}

@media (max-width: 480px) {
    .result-grid {
        grid-template-columns: 1fr;
    }
}