/* ========================================
   brent1980.com - Main Stylesheet
   Pure CSS, RWD, Dark/Light Mode
   ======================================== */

/* --- CSS Variables (Light Mode Default) --- */
:root {
  --color-bg: #ffffff;
  --color-bg-alt: #f5f7fa;
  --color-surface: #ffffff;
  --color-border: #e2e8f0;
  --color-text: #1a202c;
  --color-text-secondary: #4a5568;
  --color-text-muted: #718096;
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-primary-light: #dbeafe;
  --color-accent: #0891b2;
  --color-card-shadow: rgba(0, 0, 0, 0.08);
  --color-card-shadow-hover: rgba(0, 0, 0, 0.15);
  --color-overlay: rgba(0, 0, 0, 0.5);
  --color-code-bg: #f1f5f9;
  --color-tag-bg: #e2e8f0;
  --color-tag-text: #475569;
  --max-width: 1200px;
  --header-height: 64px;
  --radius: 8px;
  --radius-lg: 12px;
  --transition: 0.3s ease;
}

/* --- Dark Mode --- */
[data-theme="dark"] {
  --color-bg: #0f172a;
  --color-bg-alt: #1e293b;
  --color-surface: #1e293b;
  --color-border: #334155;
  --color-text: #f1f5f9;
  --color-text-secondary: #cbd5e1;
  --color-text-muted: #94a3b8;
  --color-primary: #3b82f6;
  --color-primary-hover: #60a5fa;
  --color-primary-light: #1e3a5f;
  --color-card-shadow: rgba(0, 0, 0, 0.3);
  --color-card-shadow-hover: rgba(0, 0, 0, 0.5);
  --color-overlay: rgba(0, 0, 0, 0.7);
  --color-code-bg: #1e293b;
  --color-tag-bg: #334155;
  --color-tag-text: #cbd5e1;
}

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

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans TC", sans-serif;
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background-color var(--transition), color var(--transition);
}

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

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

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

ul, ol {
  list-style: none;
}

/* --- Utility --- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 80px 0;
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--color-text);
}

.section-subtitle {
  font-size: 1.1rem;
  color: var(--color-text-secondary);
  margin-bottom: 48px;
}

.text-center {
  text-align: center;
}

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

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  border: 2px solid transparent;
  transition: all var(--transition);
  text-decoration: none;
}

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

.btn-primary:hover {
  background-color: var(--color-primary-hover);
  color: #ffffff;
}

.btn-outline {
  background-color: transparent;
  color: var(--color-primary);
  border-color: var(--color-primary);
}

.btn-outline:hover {
  background-color: var(--color-primary);
  color: #ffffff;
}

.btn-sm {
  padding: 8px 18px;
  font-size: 0.875rem;
}

/* --- Header / Navigation --- */
.header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  height: var(--header-height);
  transition: background-color var(--transition), border-color var(--transition);
}

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

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
}

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

.nav {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-link {
  padding: 8px 16px;
  color: var(--color-text-secondary);
  font-weight: 500;
  border-radius: var(--radius);
  transition: all var(--transition);
  font-size: 0.95rem;
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
}

.theme-toggle {
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 8px;
  cursor: pointer;
  color: var(--color-text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  transition: all var(--transition);
  margin-left: 8px;
}

.theme-toggle:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.theme-toggle svg {
  width: 20px;
  height: 20px;
}

/* Mobile Nav Toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--color-text);
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text);
  margin: 5px 0;
  transition: all var(--transition);
}

/* --- Hero --- */
.hero {
  padding: 100px 0 80px;
  text-align: center;
}

.hero-title {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 16px;
  line-height: 1.2;
}

.hero-title .highlight {
  color: var(--color-primary);
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--color-text-secondary);
  margin-bottom: 40px;
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
}

.hero-actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

/* --- Highlights Grid --- */
.highlights-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 24px;
}

.highlight-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  text-align: center;
  transition: all var(--transition);
}

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

.highlight-icon {
  font-size: 2.5rem;
  margin-bottom: 16px;
}

.highlight-card h3 {
  font-size: 1.15rem;
  margin-bottom: 8px;
  color: var(--color-text);
}

.highlight-card p {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
}

/* --- Works Cards --- */
.works-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 24px;
}

.work-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition);
}

.work-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px var(--color-card-shadow-hover);
}

.work-card-cover {
  width: 100%;
  height: 200px;
  object-fit: cover;
  background-color: var(--color-bg-alt);
}

.work-card-body {
  padding: 24px;
}

.work-card-category {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  padding: 4px 10px;
  border-radius: 4px;
  margin-bottom: 12px;
}

.work-card-title {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--color-text);
}

.work-card-summary {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  margin-bottom: 16px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.work-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 16px;
}

.tag {
  font-size: 0.75rem;
  padding: 4px 10px;
  background-color: var(--color-tag-bg);
  color: var(--color-tag-text);
  border-radius: 4px;
  font-weight: 500;
}

.work-card-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.work-card-date {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.work-card-links {
  display: flex;
  gap: 8px;
}

/* --- Works Filter & Search --- */
.works-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: center;
  margin-bottom: 40px;
}

.filter-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.filter-btn {
  padding: 8px 20px;
  border: 1px solid var(--color-border);
  border-radius: 24px;
  background-color: transparent;
  color: var(--color-text-secondary);
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
}

.filter-btn:hover,
.filter-btn.active {
  background-color: var(--color-primary);
  color: #ffffff;
  border-color: var(--color-primary);
}

.search-box {
  flex: 1;
  min-width: 200px;
  max-width: 320px;
  position: relative;
  margin-left: auto;
}

.search-box input {
  width: 100%;
  padding: 10px 16px 10px 40px;
  border: 1px solid var(--color-border);
  border-radius: 24px;
  background-color: var(--color-surface);
  color: var(--color-text);
  font-size: 0.95rem;
  outline: none;
  transition: border-color var(--transition);
}

.search-box input:focus {
  border-color: var(--color-primary);
}

.search-box svg {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  width: 18px;
  height: 18px;
  color: var(--color-text-muted);
}

/* --- Work Detail --- */
.work-detail-header {
  padding: 60px 0 40px;
}

.work-detail-header .work-card-category {
  margin-bottom: 16px;
}

.work-detail-title {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 16px;
}

.work-detail-summary {
  font-size: 1.15rem;
  color: var(--color-text-secondary);
  margin-bottom: 24px;
  max-width: 720px;
}

.work-detail-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: center;
  margin-bottom: 16px;
}

.work-detail-gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 16px;
  margin-bottom: 48px;
}

.work-detail-gallery img {
  width: 100%;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  cursor: pointer;
  transition: transform var(--transition);
}

.work-detail-gallery img:hover {
  transform: scale(1.02);
}

.work-detail-content {
  max-width: 800px;
}

.work-detail-content h2 {
  font-size: 1.5rem;
  margin-top: 40px;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--color-border);
}

.work-detail-content ul,
.work-detail-content ol {
  padding-left: 24px;
  margin-bottom: 16px;
}

.work-detail-content ul {
  list-style: disc;
}

.work-detail-content ol {
  list-style: decimal;
}

.work-detail-content li {
  margin-bottom: 8px;
  color: var(--color-text-secondary);
}

.work-detail-content p {
  margin-bottom: 16px;
  color: var(--color-text-secondary);
}

.work-detail-content strong {
  color: var(--color-text);
}

.work-detail-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 32px;
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
}

.work-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 60px;
  padding-top: 32px;
  border-top: 1px solid var(--color-border);
}

.work-nav a {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--color-text-secondary);
  font-weight: 500;
}

.work-nav a:hover {
  color: var(--color-primary);
}

/* --- Services --- */
.services-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.service-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  transition: all var(--transition);
}

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

.service-icon {
  font-size: 2.5rem;
  margin-bottom: 16px;
}

.service-card h3 {
  font-size: 1.2rem;
  margin-bottom: 12px;
  color: var(--color-text);
}

.service-card p {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
}

/* --- Process Steps --- */
.process-steps {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 24px;
  counter-reset: step;
}

.process-step {
  flex: 1;
  min-width: 180px;
  max-width: 220px;
  text-align: center;
  position: relative;
}

.process-step::before {
  counter-increment: step;
  content: counter(step);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background-color: var(--color-primary);
  color: #ffffff;
  font-size: 1.25rem;
  font-weight: 700;
  margin: 0 auto 16px;
}

.process-step h4 {
  font-size: 1rem;
  margin-bottom: 8px;
  color: var(--color-text);
}

.process-step p {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

/* --- FAQ --- */
.faq-list {
  max-width: 720px;
  margin: 0 auto;
}

.faq-item {
  border-bottom: 1px solid var(--color-border);
  padding: 20px 0;
}

.faq-question {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  background: none;
  border: none;
  width: 100%;
  text-align: left;
}

.faq-question::after {
  content: "+";
  font-size: 1.5rem;
  font-weight: 300;
  color: var(--color-text-muted);
  flex-shrink: 0;
  transition: transform var(--transition);
}

.faq-item.open .faq-question::after {
  transform: rotate(45deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.4s ease;
}

.faq-item.open .faq-answer {
  max-height: 500px;
  padding-top: 12px;
}

.faq-answer p {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* --- Contact Form --- */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: start;
}

.contact-info h3 {
  font-size: 1.25rem;
  margin-bottom: 24px;
}

.contact-info-item {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
  color: var(--color-text-secondary);
}

.contact-info-item svg {
  width: 20px;
  height: 20px;
  color: var(--color-primary);
  flex-shrink: 0;
}

.contact-form {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 8px;
  font-size: 0.95rem;
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background-color: var(--color-bg);
  color: var(--color-text);
  font-size: 1rem;
  font-family: inherit;
  transition: border-color var(--transition);
}

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

.form-group textarea {
  resize: vertical;
  min-height: 120px;
}

/* --- About Page --- */
.about-content {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 48px;
  align-items: start;
}

.about-avatar {
  width: 100%;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
}

.about-text h2 {
  font-size: 1.5rem;
  margin-top: 32px;
  margin-bottom: 16px;
}

.about-text h2:first-child {
  margin-top: 0;
}

.about-text p {
  color: var(--color-text-secondary);
  margin-bottom: 16px;
}

.skills-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 24px;
}

.skill-badge {
  display: inline-block;
  padding: 6px 14px;
  background-color: var(--color-primary-light);
  color: var(--color-primary);
  border-radius: 24px;
  font-size: 0.85rem;
  font-weight: 600;
}

.tech-stack {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 12px;
  margin-bottom: 24px;
}

.tech-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  background-color: var(--color-bg-alt);
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 500;
}

/* --- Footer --- */
.footer {
  margin-top: auto;
  background-color: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
  padding: 40px 0;
  transition: background-color var(--transition), border-color var(--transition);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-copy {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.footer-links {
  display: flex;
  gap: 16px;
  align-items: center;
}

.footer-links a {
  color: var(--color-text-muted);
  transition: color var(--transition);
}

.footer-links a:hover {
  color: var(--color-primary);
}

.footer-links svg {
  width: 20px;
  height: 20px;
}

/* --- Page Header --- */
.page-header {
  padding: 60px 0 40px;
  text-align: center;
  background-color: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border);
}

.page-header h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 12px;
}

.page-header p {
  font-size: 1.1rem;
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* --- 404 Page --- */
.error-page {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  min-height: 60vh;
}

.error-code {
  font-size: 8rem;
  font-weight: 800;
  color: var(--color-primary);
  line-height: 1;
  margin-bottom: 16px;
}

.error-page p {
  font-size: 1.2rem;
  color: var(--color-text-secondary);
  margin-bottom: 32px;
}

/* --- Animations --- */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- No Results --- */
.no-results {
  text-align: center;
  padding: 60px 24px;
  color: var(--color-text-muted);
  font-size: 1.1rem;
  display: none;
}

/* --- Responsive --- */
@media (max-width: 1024px) {
  .about-content {
    grid-template-columns: 200px 1fr;
  }
}

@media (max-width: 768px) {
  .nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-bg);
    flex-direction: column;
    padding: 24px;
    gap: 4px;
    transform: translateX(100%);
    transition: transform var(--transition);
    z-index: 999;
  }

  .nav.open {
    transform: translateX(0);
  }

  .nav-toggle {
    display: block;
  }

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

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

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

  .nav-link {
    display: block;
    padding: 12px 16px;
    font-size: 1.1rem;
  }

  .theme-toggle {
    margin-left: 0;
    margin-top: 16px;
  }

  .hero-title {
    font-size: 2rem;
  }

  .hero-subtitle {
    font-size: 1.05rem;
  }

  .section {
    padding: 48px 0;
  }

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

  .page-header {
    padding: 40px 0 24px;
  }

  .page-header h1 {
    font-size: 1.75rem;
  }

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

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

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

  .about-avatar {
    max-width: 200px;
    margin: 0 auto;
  }

  .skills-list {
    justify-content: center;
  }

  .tech-stack {
    grid-template-columns: 1fr 1fr;
  }

  .work-detail-title {
    font-size: 1.75rem;
  }

  .work-detail-gallery {
    grid-template-columns: 1fr;
  }

  .footer-content {
    flex-direction: column;
    text-align: center;
  }

  .works-toolbar {
    flex-direction: column;
    align-items: stretch;
  }

  .search-box {
    max-width: 100%;
    margin-left: 0;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 1.65rem;
  }

  .hero-actions {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    width: 100%;
    justify-content: center;
  }

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

  .process-steps {
    flex-direction: column;
    align-items: center;
  }

  .tech-stack {
    grid-template-columns: 1fr;
  }

  .error-code {
    font-size: 5rem;
  }
}