:root {
  --color-background: #f9fbff;
  --color-surface: #ffffff;
  --color-text: #1f2933;
  --color-muted: #52606d;
  --color-accent: #4f46e5;
  --color-accent-light: #6366f1;
  --color-border: #d2d6dc;
  --color-hero-gradient: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
  --shadow-soft: 0 20px 40px rgba(79, 70, 229, 0.08);
  --shadow-card: 0 14px 38px rgba(15, 23, 42, 0.08);

  --font-sans: "Inter", "Noto Sans JP", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
}

[data-theme="dark"] {
  --color-background: #0f172a;
  --color-surface: #111c30;
  --color-text: #e2e8f0;
  --color-muted: #94a3b8;
  --color-accent: #818cf8;
  --color-accent-light: #a5b4fc;
  --color-border: #1e293b;
  --shadow-soft: 0 20px 40px rgba(15, 23, 42, 0.45);
  --shadow-card: 0 16px 44px rgba(15, 23, 42, 0.35);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-background);
  line-height: 1.6;
}

img,
svg {
  max-width: 100%;
  display: block;
}

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

a:hover {
  text-decoration: underline;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.5rem clamp(1.5rem, 5vw, 4rem);
  position: sticky;
  top: 0;
  background: rgba(249, 251, 255, 0.9);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(210, 214, 220, 0.6);
  z-index: 10;
  transition: background 0.3s ease;
}

[data-theme="dark"] .site-header {
  background: rgba(15, 23, 42, 0.85);
  border-bottom: 1px solid rgba(30, 41, 59, 0.85);
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.brand__logo {
  display: grid;
  place-items: center;
  width: 3rem;
  height: 3rem;
  border-radius: 1rem;
  background: var(--color-hero-gradient);
  color: #fff;
  font-weight: 700;
  font-size: 1.5rem;
  box-shadow: var(--shadow-soft);
}

.brand__name {
  font-weight: 700;
  margin: 0;
}

.brand__role {
  margin: 0;
  color: var(--color-muted);
  font-size: 0.9rem;
}

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

.site-nav a {
  font-weight: 600;
  color: var(--color-muted);
  transition: color 0.2s ease;
}

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

.theme-toggle {
  border: none;
  border-radius: 50%;
  width: 2.8rem;
  height: 2.8rem;
  font-size: 1.2rem;
  cursor: pointer;
  background: var(--color-surface);
  box-shadow: var(--shadow-soft);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.theme-toggle:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-card);
}

.hero {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 3rem;
  padding: clamp(4rem, 8vw, 6rem) clamp(1.5rem, 5vw, 4rem);
}

.hero__content {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.hero__eyebrow {
  margin: 0;
  font-weight: 600;
  color: var(--color-accent);
}

.hero__description {
  margin: 0;
  color: var(--color-muted);
  font-size: 1.02rem;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.hero__image {
  min-height: 320px;
  border-radius: 2rem;
  background: var(--color-hero-gradient);
  box-shadow: var(--shadow-card);
  position: relative;
  overflow: hidden;
}

.hero__image::before,
.hero__image::after {
  content: "";
  position: absolute;
  border-radius: 50%;
  mix-blend-mode: screen;
}

.hero__image::before {
  width: 280px;
  height: 280px;
  background: rgba(255, 255, 255, 0.35);
  top: -60px;
  right: -80px;
}

.hero__image::after {
  width: 220px;
  height: 220px;
  background: rgba(255, 255, 255, 0.2);
  bottom: -80px;
  left: -40px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.6rem;
  border-radius: 999px;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.button--primary {
  background: var(--color-accent);
  color: #fff;
  box-shadow: var(--shadow-soft);
}

.button--primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-card);
}

.button--ghost {
  background: transparent;
  color: var(--color-text);
  border-color: var(--color-border);
}

.section {
  padding: clamp(4rem, 7vw, 6rem) clamp(1.5rem, 7vw, 6rem);
}

.section--alt {
  background: var(--color-surface);
  box-shadow: inset 0 1px 0 rgba(210, 214, 220, 0.3);
}

.section__header {
  max-width: 640px;
  margin-bottom: 2.5rem;
}

.section__header h2 {
  margin: 0 0 0.75rem;
  font-size: clamp(1.8rem, 3vw, 2.2rem);
}

.section__header p {
  margin: 0;
  color: var(--color-muted);
}

.about-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 2rem;
}

.about-grid article {
  background: var(--color-surface);
  padding: 1.8rem;
  border-radius: 1.5rem;
  box-shadow: var(--shadow-soft);
  border: 1px solid rgba(210, 214, 220, 0.4);
}

.about-grid h3 {
  margin-top: 0;
}

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.8rem;
}

.skill-card {
  background: var(--color-background);
  padding: 1.8rem;
  border-radius: 1.5rem;
  border: 1px solid rgba(210, 214, 220, 0.4);
  box-shadow: var(--shadow-soft);
}

.skill-card h3 {
  margin-top: 0;
}

.skill-card ul {
  padding-left: 1.2rem;
  margin: 1rem 0 0;
  color: var(--color-muted);
}

.projects-list {
  display: grid;
  gap: 2rem;
}

.project-card {
  background: var(--color-surface);
  border-radius: 1.6rem;
  padding: 2rem;
  border: 1px solid rgba(210, 214, 220, 0.35);
  box-shadow: var(--shadow-soft);
}

.project-card__tag {
  display: inline-block;
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-accent);
  background: rgba(99, 102, 241, 0.12);
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  margin-bottom: 1rem;
}

.project-card h3 {
  margin: 0 0 0.6rem;
}

.project-card p {
  margin: 0 0 1.1rem;
  color: var(--color-muted);
}

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

.timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  border-left: 2px solid rgba(99, 102, 241, 0.3);
  padding-left: 1.8rem;
}

.timeline__point {
  position: relative;
  padding: 1.5rem 0 1.5rem 1rem;
}

.timeline__point::before {
  content: "";
  position: absolute;
  left: -33px;
  top: 2.1rem;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-accent);
  box-shadow: 0 0 0 6px rgba(99, 102, 241, 0.18);
}

.timeline__time {
  font-weight: 600;
  color: var(--color-accent);
}

.contact-form {
  display: grid;
  gap: 1.5rem;
  max-width: 520px;
}

.form-row {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

label {
  font-weight: 600;
}

input,
textarea {
  padding: 0.85rem 1rem;
  border-radius: 0.9rem;
  border: 1px solid rgba(210, 214, 220, 0.6);
  background: var(--color-surface);
  color: var(--color-text);
  font-size: 1rem;
  transition: box-shadow 0.2s ease, border 0.2s ease;
}

input:focus,
textarea:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.15);
}

.contact-note {
  margin: 0;
  font-size: 0.9rem;
  color: var(--color-muted);
}

.site-footer {
  padding: 2rem clamp(1.5rem, 5vw, 4rem);
  text-align: center;
  color: var(--color-muted);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  border-top: 1px solid rgba(210, 214, 220, 0.5);
}

.to-top {
  color: var(--color-accent);
  font-weight: 600;
}

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

  .site-nav ul {
    flex-wrap: wrap;
    justify-content: center;
  }

  .hero__image {
    min-height: 260px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}