:root {
    --primary-color: #002b5b; /* 紺色 */
    --accent-color: #d4af37;  /* 金色 */
    --text-color: #333;
    --bg-color: #f9f9f9;
    --white: #ffffff;
}

body {
    font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
    margin: 0;
    padding: 0;
}

header {
    background-color: var(--white);
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
}

.logo img {
    height: 40px;
    margin-right: 10px;
}

.nav-links {
    list-style: none;
    display: flex;
}

.nav-links li {
    margin-left: 20px;
}

.nav-links a {
    text-decoration: none;
    color: var(--primary-color);
    font-weight: 500;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: var(--accent-color);
}

.hero {
    background: linear-gradient(rgba(0,43,91,0.7), rgba(0,43,91,0.7)), url('https://images.unsplash.com/photo-1523275335684-37898b6baf30?ixlib=rb-1.2.1&auto=format&fit=crop&w=1350&q=80');
    background-size: cover;
    background-position: center;
    height: 500px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: var(--white);
}

.hero-content h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.hero-content p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
}

.btn-links {
    display: flex;
    gap: 20px;
    justify-content: center;
    margin-top: 30px;
}

.btn {
    display: inline-block;
    padding: 15px 40px;
    text-decoration: none;
    border-radius: 50px;
    font-weight: bold;
    font-size: 1.2rem;
    transition: transform 0.3s, box-shadow 0.3s;
}

.btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.btn-yahoo {
    background-color: #ff0033;
    color: var(--white);
}

.btn-mercari {
    background-color: #ff0021;
    color: var(--white);
    background: linear-gradient(45deg, #ff0021, #ff4d4d);
}

section {
    padding: 80px 0;
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 50px;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 50px;
    height: 3px;
    background-color: var(--accent-color);
    margin: 15px auto 0;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.card {
    background-color: var(--white);
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    text-align: center;
}

.card i {
    font-size: 3rem;
    color: var(--accent-color);
    margin-bottom: 20px;
}

footer {
    background-color: var(--primary-color);
    color: var(--white);
    padding: 40px 0;
    text-align: center;
}

.footer-links {
    margin-bottom: 20px;
}

.footer-links a {
    color: var(--white);
    margin: 0 10px;
    text-decoration: none;
}

@media (max-width: 768px) {
    .hero-content h1 {
        font-size: 2rem;
    }
    .btn-links {
        flex-direction: column;
    }
}