:root {
    --primary-color: #0078d4;
    --secondary-color: #2b88d8;
    --accent-color: #ffb900;
    --dark-color: #333;
    --light-color: #f8f8f8;
    --text-color: #333;
    --light-text: #fff;
    --border-radius: 8px;
    --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Segoe UI', 'Meiryo UI', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--light-color);
    overflow-x: hidden;
}

header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--light-text);
    padding: 2rem 0;
    text-align: center;
    position: relative;
    box-shadow: var(--box-shadow);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    animation: fadeInDown 1s ease-out;
}

.subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: 2rem;
    animation: fadeInUp 1s ease-out 0.3s both;
}

nav {
    background-color: var(--dark-color);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--box-shadow);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    overflow-x: auto;
    padding: 1rem 0;
    scrollbar-width: none;
}

.nav-menu::-webkit-scrollbar {
    display: none;
}

.nav-menu li {
    margin-right: 1.5rem;
    white-space: nowrap;
}

.nav-menu a {
    color: var(--light-text);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    padding: 0.5rem 0;
    position: relative;
}

.nav-menu a:hover, .nav-menu a.active {
    color: var(--accent-color);
}

.nav-menu a.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 100%;
    height: 3px;
    background-color: var(--accent-color);
    border-radius: 3px;
}

main {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 2rem;
}

.intro {
    background-color: #fff;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    margin-bottom: 2rem;
    animation: fadeIn 1s ease-out;
}

.section {
    background-color: #fff;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    margin-bottom: 2rem;
    overflow: hidden;
    transition: var(--transition);
}

.section-header {
    background-color: var(--primary-color);
    color: var(--light-text);
    padding: 1rem 2rem;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.section-header:hover {
    background-color: var(--secondary-color);
}

.section-header h2 {
    font-size: 1.5rem;
    margin: 0;
}

.section-header .icon {
    transition: var(--transition);
}

.section-content {
    padding: 0;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.5s ease, padding 0.5s ease;
}

.section.active .section-content {
    padding: 2rem;
    max-height: 32768px;
}

.section.active .icon {
    transform: rotate(180deg);
}

.tech-category {
    margin-bottom: 2rem;
}

.tech-category h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: 0.5rem;
}

.tech-list {
    list-style-position: inside;
    padding-left: 1rem;
}

.tech-item {
    margin-bottom: 0.5rem;
}

.tech-name {
    font-weight: bold;
}

footer {
    background-color: var(--dark-color);
    color: var(--light-text);
    text-align: center;
    padding: 2rem 0;
    margin-top: 3rem;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes fadeInDown {
    from { 
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInUp {
    from { 
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    .subtitle {
        font-size: 1rem;
    }
    .nav-menu {
        flex-wrap: nowrap;
    }
    
    /* techStack.html用のレスポンシブ調整 */
    .feature-grid, .solution-grid, .testimonial-grid {
        grid-template-columns: 1fr;
    }
    
    .hero-title {
        font-size: 1.8rem;
    }
    
    .hero-description {
        font-size: 1rem;
    }
}

/* アクセントカラーを各セクションに適用 */
#development-tools .section-header {
    background-color: #0078d4;
}
#languages .section-header {
    background-color: #107c10;
}
#middleware .section-header {
    background-color: #5c2d91;
}
#server-cloud .section-header {
    background-color: #008575;
}
#ai-ml .section-header {
    background-color: #d83b01;
}
#cicd .section-header {
    background-color: #744da9;
}
#web-api .section-header {
    background-color: #8e562e;
}
#development-methods .section-header {
    background-color: #006666;
}

/* カラーが適用されたセクションのホバー効果 */
#development-tools .section-header:hover {
    background-color: #2b88d8;
}
#languages .section-header:hover {
    background-color: #2ea44f;
}
#middleware .section-header:hover {
    background-color: #7951a8;
}
#server-cloud .section-header:hover {
    background-color: #00a99d;
}
#ai-ml .section-header:hover {
    background-color: #ea5c31;
}
#cicd .section-header:hover {
    background-color: #8c6dc4;
}
#web-api .section-header:hover {
    background-color: #b07646;
}
#development-methods .section-header:hover {
    background-color: #00999a;
}