/* ===================================
   CSS Variables & Reset
   =================================== */
:root {
    /* Colors */
    --color-primary: #2563eb;
    --color-primary-dark: #1e40af;
    --color-secondary: #64748b;
    --color-text: #1e293b;
    --color-text-light: #64748b;
    --color-text-lighter: #94a3b8;
    --color-bg: #ffffff;
    --color-bg-alt: #f8fafc;
    --color-border: #e2e8f0;
    --color-shadow: rgba(0, 0, 0, 0.1);
    --color-shadow-medium: rgba(0, 0, 0, 0.15);

    /* Typography */
    --font-family-base: 'Noto Sans JP', 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-family-code: 'Monaco', 'Consolas', monospace;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;

    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;

    /* Container */
    --container-max-width: 1100px;
    --container-padding: 2rem;
}

/* Dark Mode Support */
@media (prefers-color-scheme: dark) {
    :root {
        --color-text: #f1f5f9;
        --color-text-light: #94a3b8;
        --color-text-lighter: #64748b;
        --color-bg: #0f172a;
        --color-bg-alt: #1e293b;
        --color-border: #334155;
        --color-shadow: rgba(0, 0, 0, 0.3);
        --color-shadow-medium: rgba(0, 0, 0, 0.5);
    }
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family-base);
    color: var(--color-text);
    background-color: var(--color-bg);
    line-height: 1.75;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ===================================
   Typography
   =================================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.25;
    color: var(--color-text);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

p {
    margin-bottom: 1rem;
}

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

a:hover {
    color: var(--color-primary-dark);
}

ul, ol {
    list-style: none;
}

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

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

.section {
    padding: var(--spacing-3xl) 0;
}

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

.section__header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.section__subtitle {
    display: inline-block;
    font-size: 0.875rem;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
}

.section__title {
    font-size: 2rem;
    font-weight: 700;
}

/* ===================================
   Header & Navigation
   =================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    transition: background-color var(--transition-base);
}

.header.scrolled {
    background-color: rgba(255, 255, 255, 0.95);
    box-shadow: 0 2px 10px var(--color-shadow);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
    padding: 0 var(--container-padding);
    max-width: var(--container-max-width);
    margin: 0 auto;
}

.nav__logo-text {
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--color-text);
}

.nav__menu {
    display: flex;
    gap: var(--spacing-md);
}

.nav__link {
    font-size: 0.9375rem;
    color: var(--color-text-light);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav__link:hover {
    color: var(--color-primary);
    background-color: var(--color-bg-alt);
}

.nav__toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    padding: var(--spacing-xs);
    background: none;
    border: none;
    cursor: pointer;
}

.nav__toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--color-text);
    border-radius: 2px;
    transition: all var(--transition-base);
}

.nav__toggle.active span:nth-child(1) {
    transform: translateY(6px) rotate(45deg);
}

.nav__toggle.active span:nth-child(2) {
    opacity: 0;
}

.nav__toggle.active span:nth-child(3) {
    transform: translateY(-6px) rotate(-45deg);
}

/* ===================================
   Buttons
   =================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.875rem 1.75rem;
    font-size: 0.9375rem;
    font-weight: 500;
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    cursor: pointer;
    border: 2px solid transparent;
}

.btn--primary {
    background-color: var(--color-primary);
    color: white;
}

.btn--primary:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.btn--secondary {
    background-color: transparent;
    color: var(--color-text);
    border-color: var(--color-border);
}

.btn--secondary:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
}

/* ===================================
   Hero Section
   =================================== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding: calc(64px + var(--spacing-2xl)) 0 var(--spacing-2xl);
}

.hero__container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
    align-items: center;
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

.hero__content {
    animation: fadeInUp 0.6s ease-out;
}

.hero__greeting {
    font-size: 1.125rem;
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
}

.hero__title-line {
    display: block;
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 700;
    line-height: 1.2;
}

.hero__description {
    font-size: 1.125rem;
    color: var(--color-text-light);
    margin: var(--spacing-md) 0 var(--spacing-lg);
}

.hero__actions {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.hero__visual {
    animation: fadeIn 0.8s ease-out 0.2s both;
}

.hero__code-block {
    background-color: #1e293b;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.2);
}

.code-block__header {
    display: flex;
    gap: 8px;
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: #334155;
}

.code-block__dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.code-block__dot--red { background-color: #ef4444; }
.code-block__dot--yellow { background-color: #f59e0b; }
.code-block__dot--green { background-color: #22c55e; }

.code-block__content {
    padding: var(--spacing-md);
    font-family: var(--font-family-code);
    font-size: 0.8125rem;
    line-height: 1.6;
    overflow-x: auto;
}

.code-block__content code {
    color: #e2e8f0;
}

.code-keyword { color: #c084fc; }
.code-class { color: #60a5fa; }
.code-string { color: #4ade80; }
.code-method { color: #fbbf24; }
.code-comment { color: #64748b; }

.hero__scroll {
    position: absolute;
    bottom: var(--spacing-xl);
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--color-text-lighter);
    font-size: 0.75rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

.hero__scroll-line {
    width: 1px;
    height: 40px;
    background: linear-gradient(to bottom, var(--color-text-lighter), transparent);
    animation: scrollBounce 2s infinite;
}

/* ===================================
   Profile Section
   =================================== */
.profile {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: var(--spacing-2xl);
}

.profile__content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.profile__main {
    padding: var(--spacing-lg);
    background-color: var(--color-bg-alt);
    border-radius: var(--radius-lg);
}

.profile__name {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
}

.profile__title {
    font-size: 1.125rem;
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: var(--spacing-md);
}

.profile__description {
    color: var(--color-text-light);
    line-height: 2;
}

.profile__details {
    display: grid;
    gap: var(--spacing-sm);
}

.profile__detail-item {
    display: flex;
    justify-content: space-between;
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid var(--color-border);
}

.profile__detail-label {
    font-weight: 500;
    color: var(--color-text-light);
}

.profile__detail-value {
    font-weight: 500;
}

.profile__stats {
    display: grid;
    grid-template-rows: repeat(3, 1fr);
    gap: var(--spacing-md);
}

.stat-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md);
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    min-width: 120px;
    text-align: center;
}

.stat-card__number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1;
}

.stat-card__label {
    font-size: 0.875rem;
    color: var(--color-text-light);
    margin-top: var(--spacing-xs);
}

/* ===================================
   Skills Section
   =================================== */
.skills {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-lg);
}

.skill-category {
    background-color: var(--color-bg);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border);
}

.skill-category__header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.skill-category__icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background-color: var(--color-bg-alt);
    border-radius: var(--radius-md);
    color: var(--color-primary);
}

.skill-category__title {
    font-size: 1.125rem;
    font-weight: 600;
}

.skill-item {
    margin-bottom: var(--spacing-md);
}

.skill-item:last-child {
    margin-bottom: 0;
}

.skill-item__header {
    display: flex;
    justify-content: space-between;
    margin-bottom: var(--spacing-xs);
}

.skill-item__name {
    font-weight: 500;
}

.skill-item__level {
    font-size: 0.875rem;
    color: var(--color-text-light);
}

.skill-item__bar {
    height: 6px;
    background-color: var(--color-bg-alt);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.skill-item__progress {
    height: 100%;
    background-color: var(--color-primary);
    border-radius: var(--radius-full);
    transition: width 0.6s ease-out;
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.skill-tag {
    padding: 0.5rem 1rem;
    background-color: var(--color-bg-alt);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    font-weight: 500;
}

/* ===================================
   Timeline (Experience)
   =================================== */
.timeline {
    position: relative;
    max-width: 900px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 20px;
    width: 2px;
    background-color: var(--color-border);
}

.timeline__item {
    position: relative;
    padding-left: 60px;
    padding-bottom: var(--spacing-xl);
}

.timeline__item:last-child {
    padding-bottom: 0;
}

.timeline__dot {
    position: absolute;
    top: 4px;
    left: 11px;
    width: 20px;
    height: 20px;
    background-color: var(--color-primary);
    border: 4px solid var(--color-bg);
    border-radius: 50%;
    box-shadow: 0 0 0 2px var(--color-primary);
}

.timeline__date {
    font-size: 0.875rem;
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: var(--spacing-xs);
}

.timeline__title {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-xs);
}

.timeline__position {
    color: var(--color-text-light);
    margin-bottom: var(--spacing-sm);
}

.timeline__description {
    color: var(--color-text);
}

.timeline__section-title {
    font-size: 0.9375rem;
    font-weight: 600;
    margin-top: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
}

.timeline__detail {
    color: var(--color-text);
    font-size: 0.9375rem;
    line-height: 1.8;
}

.timeline__list {
    list-style: disc;
    padding-left: 1.25rem;
    margin-bottom: var(--spacing-sm);
}

.timeline__list li {
    margin-bottom: var(--spacing-xs);
}

.timeline__tech {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.tech-tag {
    padding: 0.25rem 0.75rem;
    background-color: var(--color-bg-alt);
    border-radius: var(--radius-full);
    font-size: 0.8125rem;
}

/* Project Card in Timeline */
.project-card {
    padding: var(--spacing-md);
    background-color: var(--color-bg-alt);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
}

.project-card:last-child {
    margin-bottom: 0;
}

.project-card__header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.project-card__title {
    font-size: 1rem;
    font-weight: 600;
}

.project-card__role {
    padding: 0.25rem 0.75rem;
    background-color: var(--color-primary);
    color: white;
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 500;
    flex-shrink: 0;
}

.project-card__description {
    font-size: 0.9375rem;
    color: var(--color-text);
    margin-bottom: var(--spacing-sm);
    line-height: 1.8;
}

.project-card__metrics {
    display: flex;
    gap: var(--spacing-md);
}

.metric {
    text-align: center;
}

.metric__value {
    display: block;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-primary);
}

.metric__label {
    font-size: 0.75rem;
    color: var(--color-text-lighter);
}

/* ===================================
   Projects Section
   =================================== */
.projects {
    display: grid;
    gap: var(--spacing-lg);
}

.project {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: var(--spacing-lg);
    background-color: var(--color-bg);
    border-radius: var(--radius-lg);
    overflow: hidden;
    border: 1px solid var(--color-border);
    transition: all var(--transition-base);
}

.project:hover {
    box-shadow: 0 8px 24px var(--color-shadow);
    transform: translateY(-4px);
}

.project__image {
    background-color: var(--color-bg-alt);
    display: flex;
    align-items: center;
    justify-content: center;
}

.project__placeholder {
    color: var(--color-text-lighter);
}

.project__content {
    padding: var(--spacing-lg);
}

.project__tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-sm);
}

.project__tag {
    padding: 0.25rem 0.75rem;
    background-color: var(--color-primary);
    color: white;
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 500;
}

.project__title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.project__description {
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
}

.project__features {
    list-style: none;
}

.project__features li {
    position: relative;
    padding-left: 1.5rem;
    margin-bottom: var(--spacing-xs);
    color: var(--color-text-light);
    font-size: 0.9375rem;
}

.project__features li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--color-primary);
    font-weight: 700;
}

/* ===================================
   Contact Section
   =================================== */
.contact {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    max-width: 900px;
    margin: 0 auto;
}

.contact__content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.contact__text {
    font-size: 1.125rem;
    color: var(--color-text-light);
    line-height: 2;
}

.contact__info {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.contact-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.contact-item__icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    background-color: var(--color-bg-alt);
    border-radius: var(--radius-md);
    color: var(--color-primary);
    flex-shrink: 0;
}

.contact-item__content {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.contact-item__label {
    font-size: 0.75rem;
    color: var(--color-text-lighter);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.contact-item__value {
    font-weight: 500;
    color: var(--color-text);
}

.contact__message {
    display: flex;
    align-items: center;
}

.message-card {
    padding: var(--spacing-lg);
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    border-radius: var(--radius-lg);
    color: white;
}

.message-card__text {
    line-height: 2;
}

/* ===================================
   Footer
   =================================== */
.footer {
    padding: var(--spacing-lg) 0;
    background-color: var(--color-bg);
    border-top: 1px solid var(--color-border);
}

.footer__container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--container-padding);
    text-align: center;
}

.footer__copyright {
    font-size: 0.875rem;
    color: var(--color-text-lighter);
}

/* ===================================
   Animations
   =================================== */
@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes scrollBounce {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(10px);
    }
}

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 968px) {
    :root {
        --container-padding: 1.5rem;
    }

    .hero__container {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero__actions {
        justify-content: center;
    }

    .hero__visual {
        display: none;
    }

    .profile {
        grid-template-columns: 1fr;
    }

    .profile__stats {
        grid-template-columns: repeat(3, 1fr);
        grid-template-rows: 1fr;
    }

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

    .project {
        grid-template-columns: 1fr;
    }

    .project__image {
        height: 200px;
    }

    .contact {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav__menu {
        position: fixed;
        top: 64px;
        left: 0;
        right: 0;
        flex-direction: column;
        padding: var(--spacing-md);
        background-color: var(--color-bg);
        border-bottom: 1px solid var(--color-border);
        gap: 0;
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
    }

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

    .nav__item {
        width: 100%;
    }

    .nav__link {
        display: block;
        padding: var(--spacing-sm);
        border-radius: var(--radius-md);
    }

    .nav__toggle {
        display: flex;
    }

    .section {
        padding: var(--spacing-xl) 0;
    }

    .section__title {
        font-size: 1.5rem;
    }

    .profile__stats {
        grid-template-columns: 1fr;
    }

    .timeline::before {
        left: 10px;
    }

    .timeline__item {
        padding-left: 40px;
    }

    .timeline__dot {
        left: 1px;
    }
}

@media (max-width: 480px) {
    :root {
        --container-padding: 1rem;
    }

    h1 { font-size: 2rem; }
    h2 { font-size: 1.5rem; }
    h3 { font-size: 1.25rem; }

    .btn {
        width: 100%;
    }

    .hero__actions {
        flex-direction: column;
    }

    .br--sp {
        display: none;
    }
}

/* Utility Classes */
.hidden {
    display: none !important;
}

.visible {
    visibility: visible !important;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}