:root {
    --primary-color: #3498db;
    --secondary-color: #2c3e50;
    --background-color: #f0f2f5;
    --sidebar-bg: #ffffff;
    --card-bg: #ffffff;
    --text-color: #333333;
    --light-text-color: #7f8c8d;
    --border-color: #e0e0e0;
    --shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    --transition-speed: 0.3s;
}

*, *::before, *::after {
    box-sizing: border-box;
}

body {
    font-family: 'Roboto', 'Noto Sans JP', sans-serif;
    margin: 0;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.7;
}

.container {
    display: flex;
    max-width: 1400px;
    margin: 0 auto;
}

/* --- サイドバー --- */
.sidebar {
    width: 280px;
    background-color: var(--sidebar-bg);
    padding: 40px 20px;
    position: sticky;
    top: 0;
    height: 100vh;
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

.sidebar-inner {
    width: 100%;
}

.profile-image {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    overflow: hidden;
    margin: 0 auto 20px;
    border: 4px solid var(--primary-color);
}

.profile-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.sidebar h2 {
    margin: 0;
    font-family: 'Roboto', sans-serif;
    font-size: 1.5rem;
    color: var(--secondary-color);
}

.username {
    color: var(--light-text-color);
    margin-top: 5px;
    margin-bottom: 30px;
}

.main-nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.main-nav a {
    display: flex;
    align-items: center;
    padding: 12px 20px;
    margin-bottom: 10px;
    color: var(--secondary-color);
    text-decoration: none;
    border-radius: 8px;
    transition: background-color var(--transition-speed), color var(--transition-speed);
}

.main-nav a:hover, .main-nav a.active {
    background-color: var(--primary-color);
    color: #fff;
}

.main-nav i {
    width: 20px;
    margin-right: 15px;
    text-align: center;
}

.social-links {
    margin-top: 40px;
}

.social-links a {
    color: var(--light-text-color);
    font-size: 1.5rem;
    margin: 0 12px;
    transition: color var(--transition-speed);
}

.social-links a:hover {
    color: var(--primary-color);
}

/* --- メインコンテンツ --- */
.main-content {
    flex: 1;
    padding: 40px;
}

.content-section {
    margin-bottom: 60px;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.5s ease-out, transform 0.5s ease-out;
}

.content-section.visible {
    opacity: 1;
    transform: translateY(0);
}

.section-title {
    font-size: 2.5rem;
    color: var(--secondary-color);
    margin-bottom: 30px;
    position: relative;
    padding-bottom: 10px;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 4px;
    background-color: var(--primary-color);
}

.card {
    background-color: var(--card-bg);
    padding: 30px;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.card-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.skill-card {
    text-align: center;
}

.skill-icon {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.work-card {
    display: flex;
    flex-direction: column;
}

.work-image {
    width: 100%;
    height: 180px;
    overflow: hidden;
    border-radius: 8px 8px 0 0;
}

.work-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-speed);
}

.work-card:hover .work-image img {
    transform: scale(1.05);
}

.work-card h3 {
    margin-top: 20px;
}

.work-card p {
    flex-grow: 1;
}

.btn {
    display: inline-block;
    background-color: var(--primary-color);
    color: #fff;
    padding: 10px 20px;
    border-radius: 5px;
    text-decoration: none;
    transition: background-color var(--transition-speed);
    margin-top: 15px;
    text-align: center;
}

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

.btn i {
    margin-right: 8px;
}

/* --- フッター --- */
footer {
    text-align: center;
    margin-top: 40px;
    color: var(--light-text-color);
    font-size: 0.9rem;
}

#visitor-count {
    font-weight: bold;
    color: var(--primary-color);
}

/* --- レスポンシブ対応 --- */
@media (max-width: 992px) {
    .container {
        flex-direction: column;
    }
    .sidebar {
        width: 100%;
        height: auto;
        position: static;
        box-shadow: none;
        border-bottom: 1px solid var(--border-color);
    }
    .main-nav ul {
        display: flex;
        justify-content: center;
        flex-wrap: wrap;
    }
    .main-nav a {
        margin: 5px;
    }
    .main-nav span {
        display: none; /* スマホではアイコンのみ表示 */
    }
    .main-nav i {
        margin-right: 0;
    }
}