:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --text: #111827;
  --text-light: #374151;
  --gray: #6b7280;
  --light: #f8fafc;
  --border: #e5e7eb;
  --white: #ffffff;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.06);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,.1), 0 4px 6px -4px rgba(0,0,0,.1);
}

[data-theme="dark"] {
  --primary: #60a5fa;
  --primary-dark: #3b82f6;
  --text: #f1f5f9;
  --text-light: #cbd5e1;
  --gray: #94a3b8;
  --light: #1e293b;
  --border: #334155;
  --white: #0f172a;
  --shadow: 0 1px 3px rgba(0,0,0,.3), 0 1px 2px rgba(0,0,0,.2);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,.4), 0 4px 6px -4px rgba(0,0,0,.3);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', 'Noto Sans TC', sans-serif;
  color: var(--text);
  line-height: 1.7;
  background: var(--white);
}

.container {
  width: 90%;
  max-width: 1100px;
  margin: auto;
}

section {
  padding: 90px 0;
}

h1, h2, h3, h4 {
  line-height: 1.3;
}

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

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

/* ---- Navbar ---- */
.navbar {
  position: sticky;
  top: 0;
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  z-index: 999;
}

.nav-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 68px;
}

.logo {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -.02em;
}

.logo span {
  color: var(--primary);
}

.nav-links {
  display: flex;
  gap: 28px;
  align-items: center;
}

.nav-links a {
  color: var(--gray);
  font-size: .9rem;
  font-weight: 500;
  transition: color .2s;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--primary);
}

/* ---- Dark Mode Toggle ---- */
.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: 50%;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 1rem;
  transition: background .2s, border-color .2s;
  flex-shrink: 0;
}

.theme-toggle:hover {
  background: var(--light);
}

/* ---- Hamburger ---- */
.hamburger {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
  flex-direction: column;
  gap: 5px;
}

.hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  transition: .3s;
}

.hamburger.open span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.hamburger.open span:nth-child(2) {
  opacity: 0;
}

.hamburger.open span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ---- Buttons ---- */
.btn {
  display: inline-block;
  padding: 13px 26px;
  border-radius: 8px;
  font-weight: 500;
  font-size: .95rem;
  transition: .25s;
  cursor: pointer;
  border: none;
}

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

.btn-primary:hover {
  background: var(--primary-dark);
}

.btn-outline {
  border: 1px solid var(--border);
  color: var(--text);
}

.btn-outline:hover {
  background: var(--light);
}

/* ---- Hero ---- */
.hero {
  padding: 120px 0 100px;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  max-width: 700px;
  margin-bottom: 20px;
}

.hero p {
  font-size: 1.12rem;
  color: var(--gray);
  max-width: 600px;
  margin-bottom: 36px;
}

.hero-buttons {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
}

/* ---- Section Title ---- */
.section-title {
  text-align: center;
  margin-bottom: 56px;
}

.section-title h2 {
  font-size: clamp(1.6rem, 3vw, 2rem);
  margin-bottom: 10px;
}

.section-title p {
  color: var(--gray);
}

/* ---- Featured / Feature Grid (index) ---- */
.featured {
  background: var(--light);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
}

.feature {
  background: var(--white);
  padding: 32px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  transition: box-shadow .25s;
  cursor: pointer;
  display: block;
}

.feature:hover {
  box-shadow: var(--shadow-lg);
}

.feature-icon {
  font-size: 1.8rem;
  margin-bottom: 14px;
}

.feature h3 {
  margin-bottom: 8px;
  font-size: 1.1rem;
}

.feature p {
  color: var(--gray);
  font-size: .95rem;
}

/* ---- Skills Grid (index) ---- */
.skills {
  background: var(--white);
}

.skill-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
}

.skill-item {
  background: var(--light);
  padding: 18px 22px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  font-size: .92rem;
  font-weight: 500;
  text-align: center;
  transition: box-shadow .25s;
}

.skill-item:hover {
  box-shadow: var(--shadow-lg);
}

/* ---- Lab Teaser (index) ---- */
.lab-teaser {
  text-align: center;
  background: var(--light);
}

.lab-teaser h2 {
  font-size: clamp(1.6rem, 3vw, 2rem);
  margin-bottom: 14px;
}

.lab-teaser p {
  color: var(--gray);
  max-width: 600px;
  margin: 0 auto 28px;
}

/* ---- Card Grid ---- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
}

.card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
  transition: box-shadow .25s;
}

.card:hover {
  box-shadow: var(--shadow-lg);
}

.card h3 {
  margin-bottom: 10px;
}

.card p {
  color: var(--gray);
  font-size: .95rem;
}

.card-tag {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: .78rem;
  font-weight: 600;
  background: #eff6ff;
  color: var(--primary);
  margin-bottom: 14px;
}

.card-meta {
  color: var(--gray);
  font-size: .82rem;
  margin-bottom: 6px;
}

/* ---- Cases ---- */
.cases {
  background: var(--light);
}

.case-list {
  display: grid;
  gap: 18px;
}

.case {
  background: var(--white);
  padding: 24px 28px;
  border-left: 4px solid var(--primary);
  border-radius: 0 var(--radius) var(--radius) 0;
  box-shadow: var(--shadow);
}

/* ---- Process ---- */
.process-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.step {
  text-align: center;
}

.step-number {
  width: 48px;
  height: 48px;
  margin: 0 auto 14px;
  border-radius: 50%;
  background: var(--primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.1rem;
}

.step h3 {
  font-size: 1rem;
}

/* ---- CTA ---- */
.cta {
  text-align: center;
  background: var(--light);
}

.cta h2 {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  margin-bottom: 14px;
}

.cta p {
  color: var(--gray);
  margin-bottom: 28px;
}

/* ---- Footer ---- */
footer {
  border-top: 1px solid var(--border);
  padding: 28px 0;
  text-align: center;
  color: var(--gray);
  font-size: .88rem;
}

/* ---- Page Header ---- */
.page-header {
  padding: 80px 0 60px;
  text-align: center;
}

.page-header h1 {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  margin-bottom: 12px;
}

.page-header p {
  color: var(--gray);
  font-size: 1.05rem;
}

/* ---- Projects Page ---- */
.projects-section {
  padding: 60px 0 90px;
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
}

.project-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
  transition: box-shadow .25s;
}

.project-card:hover {
  box-shadow: var(--shadow-lg);
}

.project-icon {
  font-size: 2rem;
  margin-bottom: 14px;
}

.project-card h3 {
  margin-bottom: 8px;
  font-size: 1.1rem;
}

.project-card p {
  color: var(--gray);
  font-size: .95rem;
  margin-bottom: 16px;
}

.project-tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.project-tags span {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: .78rem;
  font-weight: 500;
  background: #eff6ff;
  color: var(--primary);
}

/* ---- Lab Page ---- */
.lab-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.lab-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: box-shadow .25s;
}

.lab-card:hover {
  box-shadow: var(--shadow-lg);
}

.lab-icon {
  font-size: 2.4rem;
  margin-bottom: 14px;
}

.lab-card h3 {
  margin-bottom: 8px;
}

.lab-card p {
  color: var(--gray);
  font-size: .9rem;
}

.status {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 20px;
  font-size: .75rem;
  font-weight: 600;
  margin-top: 12px;
}

.status-active {
  background: #dcfce7;
  color: #16a34a;
}

.status-beta {
  background: #fef3c7;
  color: #d97706;
}

.status-idea {
  background: #f3e8ff;
  color: #9333ea;
}

/* ---- Timeline (Lab) ---- */
.alt-bg {
  background: var(--light);
}

.timeline {
  display: grid;
  gap: 24px;
}

.timeline-item {
  display: flex;
  gap: 24px;
  align-items: flex-start;
}

.timeline-date {
  flex-shrink: 0;
  width: 100px;
  font-weight: 600;
  color: var(--primary);
  font-size: .9rem;
  padding-top: 4px;
}

.timeline-content h3 {
  margin-bottom: 6px;
  font-size: 1.05rem;
}

.timeline-content p {
  color: var(--gray);
  font-size: .92rem;
}

/* ---- Blog Page ---- */
.blog-list {
  display: grid;
  gap: 24px;
  padding: 60px 0 90px;
}

.blog-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 24px;
  box-shadow: var(--shadow);
  transition: box-shadow .25s;
}

.blog-card:hover {
  box-shadow: var(--shadow-lg);
}

.blog-meta {
  color: var(--gray);
  font-size: .82rem;
  margin-bottom: 6px;
}

.blog-card h3 {
  margin-bottom: 6px;
  font-size: 1.15rem;
}

.blog-card p {
  color: var(--gray);
  font-size: .92rem;
}

.blog-tag {
  flex-shrink: 0;
}

/* ---- Stack Page ---- */
.stack-section {
  padding: 60px 0 90px;
}

.stack-category {
  margin-bottom: 48px;
}

.stack-category h2 {
  font-size: 1.2rem;
  margin-bottom: 20px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--primary);
  display: inline-block;
}

.stack-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 16px;
}

.stack-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 16px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: box-shadow .25s;
}

.stack-card:hover {
  box-shadow: var(--shadow-lg);
}

.stack-card h3 {
  font-size: .9rem;
  margin-bottom: 4px;
}

.stack-card p {
  color: var(--gray);
  font-size: .78rem;
}

/* ---- Contact Page ---- */
.contact-section {
  padding: 60px 0 90px;
}

.contact-form-wrap {
  background: var(--light);
  padding: 32px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
}

.contact-info h2 {
  font-size: clamp(1.4rem, 2.5vw, 1.8rem);
  margin-bottom: 12px;
}

.contact-info p {
  color: var(--gray);
  margin-bottom: 24px;
}

.contact-methods {
  display: grid;
  gap: 16px;
}

.contact-item h3 {
  font-size: .95rem;
  margin-bottom: 4px;
}

.contact-item a {
  color: var(--primary);
}

.contact-item a:hover {
  text-decoration: underline;
}

.contact-form-wrap {
  background: var(--light);
  padding: 32px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.contact-form label {
  display: block;
  font-weight: 500;
  margin-bottom: 6px;
  font-size: .92rem;
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-family: inherit;
  font-size: .95rem;
  margin-bottom: 18px;
  transition: border-color .2s;
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: none;
  border-color: var(--primary);
}

.contact-form textarea {
  height: 140px;
  resize: vertical;
}

.form-note {
  color: var(--gray);
  font-size: .82rem;
  margin-top: 12px;
}

/* ---- Tags ---- */
.tag {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: .78rem;
  font-weight: 500;
  background: #eff6ff;
  color: var(--primary);
  margin-right: 6px;
}

/* ---- Responsive ---- */
@media (max-width: 768px) {
  .feature-grid,
  .card-grid,
  .process-grid,
  .lab-grid,
  .projects-grid {
    grid-template-columns: 1fr;
  }

  .stack-grid {
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
  }

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

  .hamburger {
    display: flex;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: var(--white);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 16px 5%;
    gap: 16px;
    box-shadow: var(--shadow-lg);
  }

  .nav-links.open {
    display: flex;
  }

  .blog-card {
    flex-direction: column;
    align-items: flex-start;
  }

  .timeline-item {
    flex-direction: column;
    gap: 8px;
  }
}