/* リセットとベーススタイル */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f8f9fa;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ヘッダー */
header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

header p {
    font-size: 1.2rem;
    opacity: 0.9;
}

/* ナビゲーション */
nav {
    background: #2c3e50;
    padding: 1rem 0;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
}

nav li {
    margin: 0 1rem;
}

nav a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    transition: background-color 0.3s;
}

nav a:hover {
    background-color: #34495e;
}

/* メインコンテンツ */
main {
    padding: 2rem 0;
}

.hero {
    text-align: center;
    margin-bottom: 3rem;
    padding: 2rem;
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.hero h2 {
    font-size: 2rem;
    color: #2c3e50;
    margin-bottom: 1rem;
}

.hero p {
    font-size: 1.2rem;
    color: #7f8c8d;
}

/* 計算機グリッド */
.calculator-grid, .category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.calculator-card, .category-card {
    background: white;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s, box-shadow 0.3s;
}

.calculator-card:hover, .category-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px rgba(0,0,0,0.15);
}

.calculator-card h3, .category-card h3 {
    color: #2c3e50;
    margin-bottom: 1rem;
}

.calculator-card p, .category-card p {
    color: #7f8c8d;
    margin-bottom: 1.5rem;
}

/* ボタン */
.btn {
    display: inline-block;
    background: #3498db;
    color: white;
    padding: 0.75rem 1.5rem;
    text-decoration: none;
    border-radius: 4px;
    font-weight: 500;
    transition: background-color 0.3s;
}

.btn:hover {
    background: #2980b9;
}

/* 計算機フォーム */
.calculator-form {
    background: white;
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: #2c3e50;
}

.form-group input, .form-group select {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid #e0e0e0;
    border-radius: 4px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.form-group input:focus, .form-group select:focus {
    outline: none;
    border-color: #3498db;
}

.calculate-btn {
    background: #27ae60;
    color: white;
    border: none;
    padding: 1rem 2rem;
    font-size: 1.1rem;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s;
    width: 100%;
}

.calculate-btn:hover {
    background: #219a52;
}

/* 結果表示 */
.result {
    background: white;
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    margin-top: 2rem;
}

.result h3 {
    color: #2c3e50;
    margin-bottom: 1rem;
}

.result-content {
    font-size: 1.2rem;
    line-height: 1.8;
}

.step-by-step {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 4px;
    margin-top: 1rem;
}

.step {
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid #e0e0e0;
}

.step:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

/* フッター */
footer {
    background: #2c3e50;
    color: white;
    text-align: center;
    padding: 2rem 0;
    margin-top: 3rem;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }
    
    nav ul {
        flex-direction: column;
        align-items: center;
    }
    
    nav li {
        margin: 0.5rem 0;
    }
    
    .calculator-grid, .category-grid {
        grid-template-columns: 1fr;
    }
    
    .calculator-form, .result {
        padding: 1rem;
    }
}

/* 分数表示用スタイル */
.fraction {
    display: inline-block;
    text-align: center;
    vertical-align: middle;
}

.fraction span {
    display: block;
}

.fraction .numerator {
    border-bottom: 1px solid;
    padding: 0 0.5em;
}

.fraction .denominator {
    padding: 0 0.5em;
}

/* 数式表示用 */
.math-expression {
    font-family: 'Times New Roman', serif;
    font-style: italic;
}

.highlight {
    background-color: #fff3cd;
    padding: 2px 4px;
    border-radius: 2px;
}