:root {
    --primary-color: #0d4a68;
    --secondary-color: #0b828e;
    --text-color: #333;
    --bg-light-color: #f4f7f9;
}

body {
    font-family: 'Helvetica Neue', 'Arial', 'Hiragino Sans', 'Meiryo', 'sans-serif';
    line-height: 1.8;
    color: var(--text-color);
    margin: 0;
    padding-top: 70px; /* 固定ヘッダーの高さ分 */
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
header {
    background-color: #fff;
    border-bottom: 1px solid #eee;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    height: 70px;
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.logo {
    height: 50px;
}

header nav ul {
    margin: 0;
    padding: 0;
    list-style: none;
    display: flex;
}

header nav li {
    margin-left: 30px;
}

header nav a {
    text-decoration: none;
    color: var(--primary-color);
    font-weight: bold;
    transition: color 0.3s;
}

header nav a:hover {
    color: var(--secondary-color);
}

/* Hero Section */
.hero {
    background-color: var(--primary-color);
    color: #fff;
    text-align: center;
    padding: 100px 0;
    background-image: linear-gradient(rgba(13, 74, 104, 0.8), rgba(13, 74, 104, 0.8)), url('https://source.unsplash.com/random/1600x900/?business,technology');
    background-size: cover;
    background-position: center;
}

.hero h1 {
    font-size: 2.8rem;
    margin-bottom: 20px;
}

/* Content Sections */
.content-section {
    padding: 80px 0;
    text-align: center;
}

.content-section h2 {
    font-size: 2.2rem;
    margin-bottom: 40px;
    position: relative;
    display: inline-block;
}

.content-section h2::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: var(--secondary-color);
    margin: 10px auto 0;
}

.bg-light {
    background-color: var(--bg-light-color);
}

/* Service Section */
.service-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
    text-align: left;
}

.service-item {
    background: #fff;
    padding: 30px;
    border: 1px solid #eee;
    border-radius: 8px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.05);
}

.service-item h3 {
    color: var(--primary-color);
}

/* About Section */
#about p {
    max-width: 800px;
    margin: 0 auto 40px;
    text-align: left;
}

.company-profile {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    text-align: left;
    border-collapse: collapse;
}

.company-profile th, .company-profile td {
    border: 1px solid #ddd;
    padding: 15px;
}

.company-profile th {
    background-color: var(--bg-light-color);
    width: 30%;
    font-weight: bold;
}

/* Contact Section */
.btn {
    display: inline-block;
    background: linear-gradient(45deg, var(--secondary-color), var(--primary-color));
    color: #fff;
    padding: 15px 40px;
    text-decoration: none;
    border-radius: 50px;
    font-weight: bold;
    transition: transform 0.3s;
}

.btn:hover {
    transform: scale(1.05);
}

/* Footer */
footer {
    background-color: var(--text-color);
    color: #fff;
    text-align: center;
    padding: 20px 0;
}

/* Responsive */
@media (max-width: 768px) {
    body {
        padding-top: 60px;
    }
    header {
        height: 60px;
    }
    .logo {
        height: 40px;
    }
    header nav {
        display: none; /* Simplification for mobile */
    }
    .hero h1 {
        font-size: 2rem;
    }
    .service-grid {
        grid-template-columns: 1fr;
    }
}