:root {
    --bg: #0f172a;
    --bg-alt: #111c34;
    --surface: #15213b;
    --surface-alt: #1b2946;
    --accent: #38bdf8;
    --accent-soft: rgba(56, 189, 248, 0.15);
    --text: #e2e8f0;
    --text-muted: #99a5c2;
    --border: rgba(148, 163, 184, 0.2);
    --font-sans: 'Inter', 'Noto Sans JP', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --max-width: 1120px;
    --shadow-lg: 0 24px 60px rgba(15, 23, 42, 0.45);
    --shadow-md: 0 18px 40px rgba(15, 23, 42, 0.35);
    --shadow-sm: 0 12px 24px rgba(15, 23, 42, 0.3);
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: var(--font-sans);
    background:
        radial-gradient(circle at 18% 12%, rgba(56, 189, 248, 0.16), transparent 45%),
        radial-gradient(circle at 85% 0%, rgba(37, 99, 235, 0.12), transparent 40%),
        var(--bg);
    color: var(--text);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    color: inherit;
    text-decoration: none;
}

a:hover,
a:focus {
    color: var(--accent);
}

:focus-visible {
    outline: 2px solid rgba(56, 189, 248, 0.9);
    outline-offset: 3px;
}

.container {
    width: min(var(--max-width), 92%);
    margin: 0 auto;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 99;
    background: rgba(15, 23, 42, 0.9);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 0;
}

.logo {
    font-weight: 700;
    letter-spacing: 0.08em;
}

.main-nav ul {
    display: flex;
    gap: 1.5rem;
    list-style: none;
    margin: 0;
    padding: 0;
}

.main-nav a {
    font-weight: 500;
    font-size: 0.95rem;
    color: var(--text-muted);
    transition: color 0.3s ease;
}

.main-nav a:hover,
.main-nav a:focus {
    color: var(--accent);
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text);
    display: block;
    margin: 4px 0;
    transition: transform 0.3s ease, opacity 0.3s ease;
}

.hero {
    padding: 6rem 0 4rem;
}

.hero-inner {
    display: flex;
    gap: 3rem;
    align-items: stretch;
}

.hero-text {
    flex: 1.1;
}

.hero-eyebrow {
    letter-spacing: 0.08em;
    font-size: 0.8rem;
    color: var(--accent);
    margin-bottom: 1.5rem;
}

.hero h1 {
    font-size: clamp(2.4rem, 4vw, 3.4rem);
    line-height: 1.15;
    margin: 0 0 1.5rem;
}

.hero h1 span {
    display: block;
    font-size: clamp(1rem, 2vw, 1.2rem);
    font-weight: 400;
    color: var(--text-muted);
    margin-top: 0.5rem;
}

.hero-desc {
    color: var(--text-muted);
    margin-bottom: 2.5rem;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 2rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.6rem;
    padding: 0.85rem 1.6rem;
    border-radius: 999px;
    font-weight: 600;
    font-size: 0.95rem;
    border: 1px solid transparent;
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease, color 0.25s ease;
}

.btn.primary {
    background: linear-gradient(135deg, #38bdf8, #2563eb);
    box-shadow: var(--shadow-md);
}

.btn.primary:hover,
.btn.primary:focus {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn.ghost {
    background: transparent;
    border-color: rgba(226, 232, 240, 0.4);
    color: var(--text);
}

.btn.ghost:hover,
.btn.ghost:focus {
    border-color: var(--accent);
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    gap: 1.2rem;
    margin: 0;
    padding: 0;
}

.hero-stats div {
    padding: 1.2rem;
    border: 1px solid var(--border);
    border-radius: 16px;
    background: var(--surface);
}

.hero-stats dt {
    font-size: 0.85rem;
    letter-spacing: 0.04em;
    color: var(--text-muted);
    margin-bottom: 0.4rem;
}

.hero-stats dd {
    margin: 0;
    font-size: 1.15rem;
    font-weight: 600;
}

.hero-card {
    flex: 0.9;
    display: flex;
    align-items: center;
}

.profile-card {
    width: 100%;
    background: linear-gradient(160deg, rgba(56, 189, 248, 0.12), rgba(14, 165, 233, 0.04));
    border-radius: 24px;
    padding: 2rem;
    border: 1px solid rgba(56, 189, 248, 0.25);
    box-shadow: var(--shadow-md);
}

.profile-title {
    font-weight: 600;
    margin-bottom: 1.2rem;
    color: var(--accent);
    letter-spacing: 0.04em;
}

.profile-card ul {
    margin: 0 0 1.6rem;
    padding-left: 1.1rem;
    color: var(--text);
}

.profile-card li + li {
    margin-top: 0.6rem;
}

.profile-footer {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.section {
    padding: 5rem 0;
    background: var(--bg);
    scroll-margin-top: 96px;
}

.section.alt {
    background: var(--bg-alt);
}

.section-header {
    text-align: center;
    margin: 0 auto 2.6rem;
    max-width: 760px;
}

.section-header h2 {
    font-size: clamp(2rem, 3vw, 2.4rem);
    margin: 0 0 0.6rem;
}

.section-header p {
    color: var(--text-muted);
    margin: 0 auto;
    max-width: 62ch;
}

.about-grid {
    display: grid;
    gap: 1.5rem;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.about-card {
    padding: 1.9rem;
    border-radius: 20px;
    background: var(--surface);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
}

.about-card h3 {
    margin-top: 0;
    margin-bottom: 1rem;
}

.about-card ul {
    margin: 0;
    padding-left: 1.2rem;
    color: var(--text);
}

.about-card li + li {
    margin-top: 0.5rem;
}

.skills-wrapper {
    display: grid;
    gap: 1.5rem;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.skill-column {
    padding: 1.8rem;
    border-radius: 20px;
    background: var(--surface);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
}

.skill-column h3 {
    margin-top: 0;
    margin-bottom: 1rem;
}

.skill-column ul {
    margin: 0;
    padding-left: 1.1rem;
    color: var(--text-muted);
}

.skill-column li + li {
    margin-top: 0.5rem;
}

.filter-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    justify-content: center;
    margin-bottom: 2.5rem;
}

.filter-btn {
    padding: 0.65rem 1.4rem;
    border-radius: 999px;
    border: 1px solid var(--border);
    background: transparent;
    color: var(--text-muted);
    font-weight: 500;
    cursor: pointer;
    transition: all 0.25s ease;
}

.filter-btn:hover,
.filter-btn:focus {
    border-color: var(--accent);
    color: var(--accent);
}

.filter-btn.active {
    background: var(--accent);
    color: #0b1120;
    border-color: var(--accent);
    box-shadow: 0 10px 30px rgba(56, 189, 248, 0.35);
}

.experience-list {
    display: grid;
    gap: 1.5rem;
}

.experience-card {
    padding: 2rem;
    border-radius: 22px;
    background: var(--surface);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    display: grid;
    gap: 1.2rem;
}

.experience-header {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: space-between;
    align-items: flex-start;
}

.experience-meta {
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
}

.experience-meta span {
    font-size: 0.9rem;
    color: var(--text-muted);
}

.experience-meta .project-title {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text);
}

.tag-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.45rem;
    align-items: flex-start;
}

.tag {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.35rem 0.9rem;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
    line-height: 1.2;
    white-space: nowrap;
    background: var(--accent-soft);
    color: var(--accent);
}

.tag[data-tag='pm'] {
    background: rgba(167, 139, 250, 0.16);
    color: #a78bfa;
}

.tag[data-tag='dx'] {
    background: rgba(34, 211, 238, 0.16);
    color: #22d3ee;
}

.tag[data-tag='cloud'] {
    background: rgba(56, 189, 248, 0.16);
    color: var(--accent);
}

.tag[data-tag='ai'] {
    background: rgba(74, 222, 128, 0.16);
    color: #4ade80;
}

.tag[data-tag='public'] {
    background: rgba(251, 191, 36, 0.16);
    color: #fbbf24;
}

.experience-body ul {
    margin: 0;
    padding-left: 1.15rem;
    color: var(--text-muted);
}

.experience-body li + li {
    margin-top: 0.5rem;
}

.experience-outcome {
    padding: 1.2rem;
    border-radius: 18px;
    background: rgba(56, 189, 248, 0.1);
    border: 1px solid rgba(56, 189, 248, 0.25);
}

.experience-outcome strong {
    display: block;
    margin-bottom: 0.6rem;
    color: var(--accent);
}

.strength-grid {
    display: grid;
    gap: 1.5rem;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.strength-card {
    padding: 2rem;
    border-radius: 20px;
    background: var(--surface);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
}

.vision-content {
    display: grid;
    gap: 1.5rem;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.vision-card {
    padding: 2rem;
    border-radius: 20px;
    background: var(--surface);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
}

.about-card,
.skill-column,
.experience-card,
.strength-card,
.vision-card {
    transition: transform 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
}

.vision-card ul {
    margin: 0;
    padding-left: 1.15rem;
    color: var(--text-muted);
}

.contact-card {
    padding: 2.4rem;
    border-radius: 24px;
    background: linear-gradient(145deg, rgba(56, 189, 248, 0.15), rgba(14, 165, 233, 0.05));
    border: 1px solid rgba(56, 189, 248, 0.3);
    box-shadow: var(--shadow-md);
    text-align: center;
    max-width: 680px;
    margin: 0 auto;
}

.contact-note {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.site-footer {
    padding: 2rem 0;
    border-top: 1px solid var(--border);
    background: #0b1120;
}

.footer-inner {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: space-between;
    align-items: center;
    color: var(--text-muted);
}

.back-to-top {
    font-size: 0.9rem;
    color: var(--accent);
}

/* Animation */
.section {
    position: relative;
}

.section::before {
    content: '';
    position: absolute;
    inset: 0;
    pointer-events: none;
    opacity: 0.08;
    background: radial-gradient(circle at top right, rgba(56, 189, 248, 0.25), transparent 55%);
}

@media (hover: hover) {
    .about-card:hover,
    .skill-column:hover,
    .experience-card:hover,
    .strength-card:hover,
    .vision-card:hover {
        transform: translateY(-3px);
        border-color: rgba(56, 189, 248, 0.35);
        box-shadow: var(--shadow-md);
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        transition-duration: 0.001ms !important;
        animation-duration: 0.001ms !important;
        animation-iteration-count: 1 !important;
    }
}

/* Responsive */
@media (max-width: 992px) {
    .hero-inner {
        flex-direction: column;
    }

    .hero-card {
        order: -1;
    }

    .hero-text {
        text-align: center;
    }

    .hero-actions {
        justify-content: center;
    }

    .hero-stats div {
        text-align: center;
    }
}

@media (max-width: 768px) {
    .header-inner {
        flex-wrap: wrap;
        gap: 1rem;
    }

    .nav-toggle {
        display: block;
    }

    .main-nav {
        width: 100%;
    }

    .main-nav ul {
        flex-direction: column;
        padding: 0;
        margin-top: 0.5rem;
        background: rgba(15, 23, 42, 0.95);
        border: 1px solid var(--border);
        border-radius: 14px;
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s ease;
    }

    .main-nav ul.open {
        max-height: min(70vh, 420px);
        overflow-y: auto;
    }

    .main-nav li {
        border-bottom: 1px solid rgba(148, 163, 184, 0.14);
    }

    .main-nav li:last-child {
        border-bottom: none;
    }

    .main-nav a {
        display: block;
        padding: 0.85rem 1.2rem;
    }
}

@media (max-width: 576px) {
    .hero {
        padding: 5rem 0 3rem;
    }

    .hero-stats {
        grid-template-columns: 1fr;
    }

    .experience-card {
        padding: 1.6rem;
    }

    .contact-card {
        padding: 2rem;
    }
}