* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: #f5f5f5;
    color: #333;
    line-height: 1.6;
}

/* ログイン画面 */
.login-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.login-box {
    background: white;
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    text-align: center;
    max-width: 360px;
    width: 100%;
}

.login-box h1 {
    font-size: 24px;
    margin-bottom: 8px;
    color: #2c3e50;
}

.login-box .subtitle {
    color: #666;
    margin-bottom: 30px;
    font-size: 14px;
}

.login-box input[type="password"] {
    width: 100%;
    padding: 14px;
    font-size: 18px;
    text-align: center;
    border: 2px solid #ddd;
    border-radius: 8px;
    margin-bottom: 16px;
    letter-spacing: 8px;
}

.login-box input[type="password"]:focus {
    outline: none;
    border-color: #3498db;
}

.login-box button {
    width: 100%;
    padding: 14px;
    font-size: 16px;
    background: #3498db;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.3s;
}

.login-box button:hover {
    background: #2980b9;
}

.error-message {
    color: #e74c3c;
    font-size: 14px;
    margin-top: 12px;
    display: none;
}

/* メインレイアウト */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

header {
    background: white;
    padding: 16px 20px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    margin-bottom: 0;
}

header .header-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

header h1 {
    font-size: 20px;
    color: #2c3e50;
}

.logout-btn {
    padding: 8px 16px;
    font-size: 14px;
    background: #e74c3c;
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
}

.logout-btn:hover {
    background: #c0392b;
}

/* ナビゲーション */
.nav-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.nav-card {
    background: white;
    padding: 24px;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
    text-decoration: none;
    color: inherit;
    transition: transform 0.2s, box-shadow 0.2s;
}

.nav-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.nav-card h2 {
    font-size: 18px;
    margin-bottom: 8px;
    color: #2c3e50;
}

.nav-card p {
    font-size: 14px;
    color: #666;
}

/* カレンダーセクション */
.calendar-section {
    background: white;
    border-radius: 12px;
    padding: 24px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}

.calendar-section h2 {
    font-size: 20px;
    margin-bottom: 20px;
    color: #2c3e50;
}

/* レスポンシブ */
@media (max-width: 768px) {
    .container {
        padding: 15px 12px; /* Reduced padding on mobile */
    }
    
    header {
        padding: 12px 15px;
    }
    
    header h1 {
        font-size: 18px;
    }
}

@media (max-width: 600px) {
    .login-box {
        padding: 30px 20px;
    }
    
    header h1 {
        font-size: 16px;
    }
    
    .nav-cards {
        grid-template-columns: 1fr;
    }
    
    .container {
        padding: 12px 10px; /* Even less padding on small mobile */
    }
}