body {
    margin: 0;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    color: #111827;
    background: #f9fafb;
}

.container {
    width: 90%;
    max-width: 1080px;
    margin: 0 auto;
}

/* Header */
.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(249, 250, 251, 0.9);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #e5e7eb;
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    font-size: 18px;
}

.logo-mark {
    width: 28px;
    height: 28px;
    border-radius: 8px;
    background: linear-gradient(135deg, #2563eb, #22c55e);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-weight: 800;
}

.nav {
    display: flex;
    gap: 16px;
    align-items: center;
    font-size: 14px;
}

.nav a {
    text-decoration: none;
    color: #374151;
}

.nav a:hover {
    color: #111827;
}

.nav-login {
    padding: 6px 12px;
    border-radius: 999px;
    border: 1px solid #d1d5db;
}

.nav-register {
    padding: 6px 14px;
    border-radius: 999px;
    background: #111827;
    color: #fff !important;
}

/* Hero */
.hero {
    padding: 64px 0 72px;
}

.hero-inner {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 32px;
}

.hero-text {
    flex: 1 1 320px;
}

.hero-text h1 {
    font-size: 32px;
    line-height: 1.3;
    margin-bottom: 16px;
}

.hero-lead {
    font-size: 15px;
    color: #4b5563;
    margin-bottom: 20px;
}

.hero-buttons {
    display: flex;
    gap: 12px;
    margin-bottom: 8px;
}

.btn-primary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 20px;
    border-radius: 999px;
    background: #111827;
    color: #fff;
    text-decoration: none;
    font-size: 14px;
    font-weight: 600;
}

.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 18px;
    border-radius: 999px;
    border: 1px solid #d1d5db;
    color: #374151;
    text-decoration: none;
    font-size: 14px;
}

.btn-primary:hover {
    background: #000;
}

.btn-secondary:hover {
    background: #f3f4f6;
}

.hero-note {
    font-size: 12px;
    color: #6b7280;
}

.hero-visual {
    flex: 1 1 280px;
    text-align: center;
}

.hero-visual img {
    max-width: 100%;
    height: auto;
    border-radius: 24px;
    box-shadow: 0 18px 45px rgba(15, 23, 42, 0.25);
}

/* Sections */
.section {
    padding: 56px 0;
}

.section-title {
    font-size: 24px;
    margin-bottom: 24px;
    text-align: center;
}

/* Features */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 20px;
}

.feature-item {
    background: #fff;
    border-radius: 16px;
    padding: 18px;
    box-shadow: 0 8px 20px rgba(15, 23, 42, 0.06);
}

.feature-item h3 {
    font-size: 16px;
    margin-bottom: 8px;
}

.feature-item p {
    font-size: 14px;
    color: #4b5563;
}

/* How */
.steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 20px;
}

.step {
    background: #fff;
    border-radius: 16px;
    padding: 18px;
    box-shadow: 0 8px 20px rgba(15, 23, 42, 0.06);
}

.step-number {
    display: inline-flex;
    width: 28px;
    height: 28px;
    border-radius: 999px;
    align-items: center;
    justify-content: center;
    background: #111827;
    color: #fff;
    font-size: 14px;
    margin-bottom: 8px;
}

/* Screens */
.screens-inner {
    display: flex;
    flex-wrap: wrap;
    gap: 32px;
    align-items: center;
}

.screens-text {
    flex: 1 1 320px;
    font-size: 14px;
    color: #4b5563;
}

.screens-visuals {
    flex: 1 1 280px;
    display: flex;
    gap: 12px;
    justify-content: center;
}

.screens-visuals img {
    max-width: 48%;
    border-radius: 20px;
    box-shadow: 0 14px 30px rgba(15, 23, 42, 0.18);
}

/* FAQ */
.faq-item {
    background: #fff;
    border-radius: 12px;
    padding: 14px 16px;
    margin-bottom: 10px;
    box-shadow: 0 6px 16px rgba(15, 23, 42, 0.05);
}

.faq-item h3 {
    font-size: 15px;
    margin-bottom: 4px;
}

.faq-item p {
    font-size: 14px;
    color: #4b5563;
}

/* CTA */
.cta {
    background: #111827;
    color: #f9fafb;
    text-align: center;
}

.cta-inner {
    max-width: 640px;
    margin: 0 auto;
}

.btn-large {
    margin-top: 16px;
    padding: 12px 28px;
    font-size: 15px;
}

/* Footer */
.site-footer {
    border-top: 1px solid #e5e7eb;
    padding: 18px 0 24px;
    background: #f9fafb;
}

.footer-inner {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    font-size: 12px;
    color: #6b7280;
}

.footer-links {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.footer-links a {
    text-decoration: none;
    color: #6b7280;
}

.footer-links a:hover {
    color: #111827;
}

/* Responsive */
@media (max-width: 768px) {
    .hero {
        padding-top: 40px;
    }
    .hero-text h1 {
        font-size: 24px;
    }
    .nav {
        display: none; /* 必要ならハンバーガーメニューにしてもOK */
    }
}