/* ==========================================
   CSS Custom Properties (Design Tokens)
   ========================================== */
:root {
    /* Colors */
    --color-bg: #0a0a0f;
    --color-bg-alt: #12121a;
    --color-text: #e8e8ec;
    --color-text-muted: #8b8b9a;
    --color-accent: #6366f1;
    --color-accent-light: #818cf8;
    --color-accent-glow: rgba(99, 102, 241, 0.3);
    --color-border: rgba(255, 255, 255, 0.08);
    --color-card-bg: rgba(255, 255, 255, 0.03);

    /* Typography */
    --font-sans: 'Noto Sans JP', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Consolas', monospace;

    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 2rem;
    --space-lg: 4rem;
    --space-xl: 6rem;
    --space-2xl: 10rem;

    /* Layout */
    --max-width: 1100px;
    --header-height: 70px;

    /* Animation */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* ==========================================
   Reset & Base Styles
   ========================================== */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: auto;
    /* JS handles smooth scroll */
}

body {
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.8;
    color: var(--color-text);
    background-color: var(--color-bg);
    letter-spacing: 0.02em;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color var(--transition-fast);
}

ul {
    list-style: none;
}

img {
    max-width: 100%;
    height: auto;
}

/* ==========================================
   Layout
   ========================================== */
.container {
    width: 90%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--space-sm);
}

/* ==========================================
   Header
   ========================================== */
header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: rgba(10, 10, 15, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    display: flex;
    align-items: center;
}

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

.logo {
    font-family: var(--font-mono);
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--color-accent-light);
    letter-spacing: -0.02em;
}

.cursor {
    animation: blink 1s step-end infinite;
    color: var(--color-accent);
}

@keyframes blink {

    0%,
    100% {
        opacity: 1;
    }

    50% {
        opacity: 0;
    }
}

header nav ul {
    display: flex;
    gap: var(--space-md);
}

header nav a {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-muted);
    padding: var(--space-xs) 0;
    position: relative;
}

header nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--color-accent);
    transition: width var(--transition-base);
}

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

header nav a:hover::after {
    width: 100%;
}

/* Mobile Menu Button */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 8px;
    background: none;
    border: none;
    cursor: pointer;
}

.mobile-menu-btn span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--color-text);
    transition: var(--transition-fast);
}

/* ==========================================
   Hero Section
   ========================================== */
.hero-section {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding-top: var(--header-height);
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 20%;
    left: 50%;
    transform: translateX(-50%);
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, var(--color-accent-glow) 0%, transparent 70%);
    pointer-events: none;
    opacity: 0.5;
}

.hero-content {
    text-align: center;
    position: relative;
    z-index: 1;
}

.hero-greeting {
    font-family: var(--font-mono);
    font-size: 1rem;
    color: var(--color-accent-light);
    margin-bottom: var(--space-sm);
    letter-spacing: 0.1em;
}

.hero-name {
    font-size: clamp(3rem, 10vw, 6rem);
    font-weight: 700;
    margin-bottom: var(--space-sm);
    background: linear-gradient(135deg, var(--color-text) 0%, var(--color-accent-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-tagline {
    font-family: var(--font-mono);
    font-size: 1.1rem;
    color: var(--color-text-muted);
    margin-bottom: var(--space-lg);
}

.hero-status {
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--color-text-muted);
    padding: var(--space-xs) var(--space-md);
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 50px;
}

.status-indicator {
    width: 8px;
    height: 8px;
    background: #22c55e;
    border-radius: 50%;
    animation: pulse 2s infinite;
}

@keyframes pulse {

    0%,
    100% {
        opacity: 1;
        transform: scale(1);
    }

    50% {
        opacity: 0.6;
        transform: scale(1.1);
    }
}

/* ==========================================
   Sections
   ========================================== */
.section {
    padding: var(--space-2xl) 0;
}

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

.section-title {
    font-family: var(--font-mono);
    font-size: 2rem;
    font-weight: 600;
    text-align: center;
    margin-bottom: var(--space-xl);
    position: relative;
    color: var(--color-text);
}

.section-title::after {
    content: '';
    display: block;
    width: 40px;
    height: 3px;
    background: var(--color-accent);
    margin: var(--space-sm) auto 0;
}

/* ==========================================
   About Section
   ========================================== */
.about-card {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: var(--space-lg);
    align-items: start;
}

.about-text {
    padding-right: var(--space-lg);
}

.about-lead {
    font-size: 1.25rem;
    font-weight: 500;
    margin-bottom: var(--space-md);
    color: var(--color-text);
}

.about-text p {
    color: var(--color-text-muted);
    margin-bottom: var(--space-md);
}

.about-text p:last-child {
    margin-bottom: 0;
}

.about-meta {
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 16px;
    padding: var(--space-md);
}

.meta-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.meta-item {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
}

.meta-item dt {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--color-accent-light);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.meta-item dd {
    font-family: var(--font-mono);
    font-size: 1rem;
    color: var(--color-text);
}

/* ==========================================
   Skills Section
   ========================================== */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-md);
}

.skill-card {
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 16px;
    padding: var(--space-lg);
    transition: transform var(--transition-base), border-color var(--transition-base);
}

.skill-card:hover {
    transform: translateY(-4px);
    border-color: var(--color-accent);
}

.skill-icon {
    font-size: 2rem;
    margin-bottom: var(--space-md);
    color: var(--color-accent-light);
}

.skill-card h3 {
    font-family: var(--font-mono);
    font-size: 1.1rem;
    margin-bottom: var(--space-sm);
    color: var(--color-text);
}

.skill-card p {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    line-height: 1.7;
}

/* ==========================================
   Interests Section
   ========================================== */
.interests-content {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-lg);
}

.interest-item {
    padding: var(--space-lg);
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 16px;
}

.interest-item h3 {
    font-family: var(--font-mono);
    font-size: 1.2rem;
    margin-bottom: var(--space-sm);
    color: var(--color-accent-light);
}

.interest-item p {
    color: var(--color-text-muted);
    margin-bottom: var(--space-md);
    line-height: 1.8;
}

.tag-list {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-xs);
}

.tag {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--color-accent-light);
    background: rgba(99, 102, 241, 0.1);
    padding: 4px 12px;
    border-radius: 20px;
    border: 1px solid rgba(99, 102, 241, 0.2);
}

/* ==========================================
   Contact Section
   ========================================== */
.contact-card {
    max-width: 500px;
    margin: 0 auto;
    text-align: center;
    padding: var(--space-xl);
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 24px;
}

.contact-handle {
    font-family: var(--font-mono);
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: var(--space-sm);
    color: var(--color-text);
}

.contact-note {
    color: var(--color-text-muted);
    margin-bottom: var(--space-md);
}

.contact-links {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
    margin-bottom: var(--space-md);
}

.contact-link {
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    font-family: var(--font-mono);
    font-size: 0.9rem;
    color: var(--color-text-muted);
    padding: var(--space-xs) var(--space-sm);
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    transition: all var(--transition-fast);
}

.contact-link:hover {
    color: var(--color-accent-light);
    border-color: var(--color-accent);
    background: rgba(99, 102, 241, 0.05);
}

.link-icon {
    font-size: 1rem;
}

.contact-status {
    margin-top: var(--space-md);
}

.status-badge {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    padding: var(--space-xs) var(--space-md);
    background: rgba(34, 197, 94, 0.1);
    color: #22c55e;
    border: 1px solid rgba(34, 197, 94, 0.3);
    border-radius: 50px;
}

/* Salary Range */
.salary-range {
    margin-top: var(--space-md);
    padding: var(--space-md);
    background: rgba(99, 102, 241, 0.05);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: 12px;
}

.salary-label {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--color-accent-light);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: var(--space-xs);
}

.salary-value {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--color-text);
}

.salary-note {
    font-size: 0.8rem;
    color: var(--color-text-muted);
    margin-top: var(--space-xs);
}

/* ==========================================
   Environment Section
   ========================================== */
.env-content {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-lg);
}

.env-block {
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 16px;
    padding: var(--space-lg);
}

.env-block h3 {
    font-family: var(--font-mono);
    font-size: 1.1rem;
    color: var(--color-accent-light);
    margin-bottom: var(--space-md);
    padding-bottom: var(--space-xs);
    border-bottom: 1px solid var(--color-border);
}

.env-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.env-list li {
    font-size: 0.95rem;
    color: var(--color-text-muted);
    line-height: 1.6;
}

.env-list li strong {
    color: var(--color-text);
    font-weight: 500;
}

/* ==========================================
   Footer
   ========================================== */
footer {
    padding: var(--space-lg) 0;
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.footer-text {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    margin-bottom: var(--space-sm);
}

.back-to-top {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--color-accent-light);
    transition: color var(--transition-fast);
}

.back-to-top:hover {
    color: var(--color-accent);
}

/* ==========================================
   Responsive Design
   ========================================== */
@media (max-width: 1024px) {
    .skills-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .env-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    :root {
        --space-lg: 3rem;
        --space-xl: 4rem;
        --space-2xl: 6rem;
    }

    /* Header Mobile */
    header nav {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        background: var(--color-bg);
        border-bottom: 1px solid var(--color-border);
        padding: var(--space-md);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: transform var(--transition-base), opacity var(--transition-base);
    }

    header nav.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    header nav ul {
        flex-direction: column;
        align-items: center;
        gap: var(--space-md);
    }

    .mobile-menu-btn {
        display: flex;
    }

    .mobile-menu-btn.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .mobile-menu-btn.active span:nth-child(2) {
        opacity: 0;
    }

    .mobile-menu-btn.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }

    /* About */
    .about-card {
        grid-template-columns: 1fr;
    }

    .about-text {
        padding-right: 0;
    }

    /* Skills */
    .skills-grid {
        grid-template-columns: 1fr;
    }

    /* Interests */
    .interests-content {
        grid-template-columns: 1fr;
    }

    /* Environment */
    .env-content {
        grid-template-columns: 1fr;
    }

    /* Hero */
    .hero-name {
        font-size: 3rem;
    }

    .section-title {
        font-size: 1.5rem;
    }
}

@media (max-width: 480px) {
    .container {
        width: 95%;
    }

    .hero-tagline {
        font-size: 0.9rem;
    }

    .contact-card {
        padding: var(--space-lg);
    }

    .contact-handle {
        font-size: 1.5rem;
    }

    .salary-value {
        font-size: 1.25rem;
    }
}