/* ===========================
   RESET & BASE
=========================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --blue-900: #0c2461;
  --blue-700: #1a56db;
  --blue-600: #1d4ed8;
  --blue-500: #3b82f6;
  --blue-100: #dbeafe;
  --blue-50:  #eff6ff;
  --white:    #ffffff;
  --gray-50:  #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-400: #94a3b8;
  --gray-600: #475569;
  --gray-900: #0f172a;

  --font: 'Helvetica Neue', 'Hiragino Kaku Gothic ProN', 'BIZ UDPGothic', Meiryo, sans-serif;
  --radius: 12px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.05);
  --shadow-md: 0 4px 16px rgba(0,0,0,.10);
  --shadow-lg: 0 12px 40px rgba(0,0,0,.12);
  --transition: 0.3s cubic-bezier(.4,0,.2,1);
}

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

body {
  font-family: var(--font);
  color: var(--gray-900);
  background: var(--white);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

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

.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ===========================
   HEADER
=========================== */
.header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--gray-200);
  transition: box-shadow var(--transition);
}
.header.scrolled {
  box-shadow: var(--shadow-md);
}
.header-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 24px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--blue-700);
  letter-spacing: -.02em;
}
.nav {
  display: flex;
  gap: 2rem;
  align-items: center;
}
.nav a {
  font-size: .9rem;
  font-weight: 500;
  color: var(--gray-600);
  transition: color var(--transition);
}
.nav a:hover { color: var(--blue-700); }
.nav-cta {
  background: var(--blue-700);
  color: var(--white) !important;
  padding: 6px 18px;
  border-radius: 999px;
  transition: background var(--transition), transform var(--transition) !important;
}
.nav-cta:hover {
  background: var(--blue-600) !important;
  transform: translateY(-1px);
}
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--gray-900);
  border-radius: 2px;
  transition: var(--transition);
}

/* ===========================
   HERO
=========================== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  padding-top: 64px;
}
.hero-bg {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, var(--blue-900) 0%, #1e3a8a 40%, #1e40af 70%, var(--blue-500) 100%);
  z-index: 0;
}
.hero-bg::after {
  content: '';
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 60% 50% at 80% 50%, rgba(59,130,246,.25) 0%, transparent 70%),
    url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.03'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
}
.hero-content {
  position: relative;
  z-index: 1;
  color: var(--white);
  padding: 80px 24px;
}
.hero-inner {
  display: flex;
  align-items: center;
  gap: 64px;
}
.hero-text {
  flex: 1;
  min-width: 0;
}
.hero-avatar {
  flex-shrink: 0;
  width: 220px;
  opacity: 0;
}
.hero-avatar img {
  width: 100%;
  filter: drop-shadow(0 16px 40px rgba(0,0,0,.4));
  animation: floatAvatar 4s ease-in-out infinite;
}
@keyframes floatAvatar {
  0%, 100% { transform: translateY(0); }
  50%       { transform: translateY(-12px); }
}
.hero-label {
  font-size: .85rem;
  font-weight: 600;
  letter-spacing: .15em;
  text-transform: uppercase;
  color: var(--blue-100);
  margin-bottom: 1rem;
  opacity: 0;
}
.hero-name {
  font-size: clamp(3rem, 8vw, 5.5rem);
  font-weight: 800;
  letter-spacing: -.04em;
  line-height: 1.05;
  margin-bottom: 1.5rem;
  opacity: 0;
}
.hero-desc {
  font-size: 1.1rem;
  color: var(--blue-100);
  max-width: 560px;
  line-height: 1.8;
  margin-bottom: 2rem;
  opacity: 0;
}
.hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 2.5rem;
  opacity: 0;
}
.tag {
  background: rgba(255,255,255,.15);
  color: var(--white);
  border: 1px solid rgba(255,255,255,.25);
  padding: 4px 14px;
  border-radius: 999px;
  font-size: .82rem;
  font-weight: 500;
  backdrop-filter: blur(4px);
}
.btn {
  display: inline-block;
  background: var(--white);
  color: var(--blue-700);
  font-weight: 700;
  font-size: .95rem;
  padding: 14px 32px;
  border-radius: 999px;
  transition: transform var(--transition), box-shadow var(--transition);
  opacity: 0;
}
.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0,0,0,.2);
}
.btn-outline {
  background: transparent;
  color: var(--blue-700);
  border: 2px solid var(--blue-700);
  opacity: 1;
}
.btn-outline:hover {
  background: var(--blue-700);
  color: var(--white);
  box-shadow: 0 8px 24px rgba(26,86,219,.3);
}
.hero-scroll-hint {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1;
}
.hero-scroll-hint span {
  display: block;
  width: 22px;
  height: 36px;
  border: 2px solid rgba(255,255,255,.4);
  border-radius: 999px;
  position: relative;
}
.hero-scroll-hint span::after {
  content: '';
  position: absolute;
  top: 6px;
  left: 50%;
  transform: translateX(-50%);
  width: 4px;
  height: 8px;
  background: rgba(255,255,255,.7);
  border-radius: 2px;
  animation: scrollDot 1.8s ease-in-out infinite;
}
@keyframes scrollDot {
  0%   { opacity: 1; transform: translateX(-50%) translateY(0); }
  80%  { opacity: 0; transform: translateX(-50%) translateY(12px); }
  100% { opacity: 0; transform: translateX(-50%) translateY(0); }
}

/* ===========================
   SECTIONS COMMON
=========================== */
.section {
  padding: 96px 0;
}
.section-alt {
  background: var(--gray-50);
}
.section-title {
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  font-weight: 800;
  letter-spacing: -.03em;
  margin-bottom: 48px;
  position: relative;
  display: inline-block;
}
.section-title::after {
  content: '';
  position: absolute;
  left: 0; bottom: -10px;
  width: 40px; height: 4px;
  background: var(--blue-500);
  border-radius: 2px;
}
.section-sub {
  color: var(--gray-600);
  margin-top: -32px;
  margin-bottom: 40px;
}

/* ===========================
   ABOUT
=========================== */
.about-grid {
  display: grid;
  grid-template-columns: 180px 1fr 1fr;
  gap: 48px;
  align-items: start;
}
.about-avatar img {
  width: 100%;
  border-radius: 50%;
  border: 4px solid var(--blue-100);
  box-shadow: var(--shadow-md);
}
.about-text p {
  color: var(--gray-600);
  margin-bottom: 1.2rem;
  font-size: 1rem;
}
.about-langs h3 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--gray-900);
  margin-bottom: 16px;
}
.lang-list {
  list-style: none;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}
.lang-list li {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--gray-100);
  padding: 10px 14px;
  border-radius: 8px;
  font-size: .9rem;
  font-weight: 500;
  transition: background var(--transition), transform var(--transition);
}
.lang-list li:hover {
  background: var(--blue-50);
  transform: translateX(4px);
}
.lang-icon {
  font-size: 1.1rem;
}

/* ===========================
   SKILLS
=========================== */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.skill-card {
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 28px 24px;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}
.skill-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--blue-100);
}
.skill-icon {
  font-size: 2rem;
  margin-bottom: 12px;
}
.skill-card h3 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--blue-700);
}
.skill-card p {
  font-size: .875rem;
  color: var(--gray-600);
  line-height: 1.65;
}

/* ===========================
   CERTIFICATIONS
=========================== */
.certs-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
}
.cert-group {
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 28px;
}
.cert-category {
  font-size: .8rem;
  font-weight: 700;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--blue-500);
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--gray-100);
}
.cert-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.cert-list li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: .9rem;
  color: var(--gray-600);
}
.cert-badge {
  display: inline-block;
  font-size: .7rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 4px;
  white-space: nowrap;
  flex-shrink: 0;
}
.cert-badge.blue   { background: #dbeafe; color: #1e40af; }
.cert-badge.orange { background: #ffedd5; color: #c2410c; }
.cert-badge.sky    { background: #e0f2fe; color: #0369a1; }
.cert-badge.dark   { background: #1e293b; color: #f1f5f9; }
.cert-badge.red    { background: #fee2e2; color: #b91c1c; }
.cert-badge.brown  { background: #fef3c7; color: #92400e; }
.cert-badge.purple { background: #f3e8ff; color: #7e22ce; }
.cert-badge.teal   { background: #ccfbf1; color: #0f766e; }
.cert-badge.gray   { background: var(--gray-100); color: var(--gray-600); }

/* ===========================
   WORKS
=========================== */
.works-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}
.work-card {
  display: flex;
  flex-direction: column;
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 28px;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  cursor: pointer;
}
.work-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: var(--blue-500);
}
.work-card:hover .work-link {
  color: var(--blue-700);
  transform: translateX(4px);
}
.work-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}
.work-num {
  font-size: 2rem;
  font-weight: 800;
  color: var(--blue-100);
  line-height: 1;
}
.work-tags {
  display: flex;
  gap: 6px;
}
.tag-sm {
  background: var(--blue-50);
  color: var(--blue-700);
  font-size: .72rem;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 4px;
}
.work-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--gray-900);
}
.work-card p {
  font-size: .88rem;
  color: var(--gray-600);
  line-height: 1.65;
  flex: 1;
  margin-bottom: 16px;
}
.work-link {
  font-size: .85rem;
  font-weight: 600;
  color: var(--gray-400);
  display: inline-block;
  transition: color var(--transition), transform var(--transition);
}

/* ===========================
   CONTACT
=========================== */
.contact-section {
  background: var(--blue-900);
  color: var(--white);
  text-align: center;
}
.contact-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
}
.contact-links {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  justify-content: center;
}
.contact-section .section-title {
  color: var(--white);
}
.contact-section .section-title::after {
  background: var(--blue-100);
}
.contact-section p {
  color: var(--blue-100);
  font-size: 1rem;
  margin-bottom: 8px;
}

/* ===========================
   FOOTER
=========================== */
.footer {
  background: var(--gray-900);
  color: var(--gray-400);
  padding: 24px 0;
  font-size: .85rem;
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
}
.footer-credit {
  font-size: .75rem;
  color: var(--gray-600);
}
.footer-credit a {
  color: var(--gray-600);
  text-decoration: underline;
  text-underline-offset: 2px;
}
.footer-credit a:hover {
  color: var(--gray-400);
}

/* ===========================
   BACK TO TOP
=========================== */
.back-to-top {
  position: fixed;
  bottom: 36px;
  right: 36px;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--blue-500), var(--blue-700));
  color: var(--white);
  font-size: 1.4rem;
  font-weight: bold;
  border: none;
  cursor: pointer;
  box-shadow: 0 6px 24px rgba(59,130,246,.5);
  opacity: 0;
  visibility: hidden;
  transform: translateY(16px) scale(.9);
  transition: opacity .3s ease, visibility .3s ease, transform .3s ease, box-shadow .2s ease;
  z-index: 900;
  display: flex;
  align-items: center;
  justify-content: center;
}
.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
}
.back-to-top:hover {
  transform: translateY(-3px) scale(1.08);
  box-shadow: 0 10px 32px rgba(59,130,246,.6);
}
.back-to-top:active {
  transform: scale(.96);
}

@media (max-width: 768px) {
  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 48px;
    height: 48px;
    font-size: 1.2rem;
  }
}

/* ===========================
   ANIMATIONS
=========================== */
.fade-up {
  opacity: 0;
  transform: translateY(30px);
}
.fade-up.animated {
  animation: fadeUp .8s var(--transition) forwards;
}

.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity .6s ease, transform .6s ease;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

.delay-1 { transition-delay: .1s; }
.delay-2 { transition-delay: .2s; }
.delay-3 { transition-delay: .3s; }
.delay-4 { transition-delay: .4s; }

/* hero delays via animation-delay */
.hero .delay-1 { animation-delay: .15s; }
.hero .delay-2 { animation-delay: .3s; }
.hero .delay-3 { animation-delay: .45s; }
.hero .delay-4 { animation-delay: .6s; }

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(30px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ===========================
   RESPONSIVE
=========================== */
@media (max-width: 768px) {
  .nav {
    display: none;
    position: absolute;
    top: 64px; left: 0; right: 0;
    background: var(--white);
    flex-direction: column;
    gap: 0;
    border-bottom: 1px solid var(--gray-200);
    box-shadow: var(--shadow-md);
  }
  .nav.open {
    display: flex;
  }
  .nav a {
    padding: 14px 24px;
    border-bottom: 1px solid var(--gray-100);
    width: 100%;
  }
  .nav-cta {
    margin: 12px 24px;
    width: auto;
    text-align: center;
    border-radius: 999px;
  }
  .hamburger { display: flex; }

  .about-grid { grid-template-columns: 1fr; gap: 32px; }
  .about-avatar { width: 120px; margin: 0 auto; }
  .hero-inner { flex-direction: column-reverse; gap: 32px; }
  .hero-avatar { width: 160px; margin: 0 auto; }
  .skills-grid { grid-template-columns: repeat(2, 1fr); }
  .certs-grid  { grid-template-columns: 1fr; }
  .works-grid  { grid-template-columns: 1fr; }
  .section { padding: 64px 0; }
}

@media (max-width: 480px) {
  .skills-grid { grid-template-columns: 1fr; }
  .lang-list   { grid-template-columns: 1fr; }
}