/* ========== 設計 token（亮/暗共用變數）========== */
:root {
  --bg: #f5f0eb;
  --bg-card: #fff;
  --text: #1a1a1a;
  --text-muted: #5c5c5c;
  --accent: #c45c26;
  --accent-soft: rgba(196, 92, 38, 0.15);
  --border: rgba(0, 0, 0, 0.08);
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
  --font-sans: "Noto Sans TC", sans-serif;
  --font-mono: "JetBrains Mono", monospace;
  --radius: 12px;
  --radius-sm: 8px;
  --header-height: 64px;
  --transition: 0.25s ease;
}

[data-theme="dark"] {
  --bg: #0f0f0f;
  --bg-card: #1a1a1a;
  --text: #e8e6e3;
  --text-muted: #9a9a9a;
  --accent: #e07d3c;
  --accent-soft: rgba(224, 125, 60, 0.2);
  --border: rgba(255, 255, 255, 0.08);
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
}

/* ========== Base ========== */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: background var(--transition), color var(--transition);
}

.container {
  width: 100%;
  max-width: 1100px;
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.25rem;
  padding-right: 1.25rem;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ========== Header & Nav ========== */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow);
  transition: background var(--transition), border-color var(--transition);
}

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

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

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--text);
  font-weight: 500;
}
.nav-links a:hover { color: var(--accent); }

.theme-toggle {
  position: relative;
  width: 44px;
  height: 44px;
  border: none;
  border-radius: var(--radius-sm);
  background: var(--accent-soft);
  color: var(--accent);
  cursor: pointer;
  font-size: 1.25rem;
  transition: transform var(--transition), background var(--transition);
}
.theme-toggle:hover { background: var(--accent); color: var(--bg); transform: scale(1.05); }

.icon-moon { display: none; }
[data-theme="dark"] .icon-sun { display: none; }
[data-theme="dark"] .icon-moon { display: inline; }

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  padding: 0;
  border: none;
  background: transparent;
  cursor: pointer;
  color: var(--text);
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: currentColor;
  border-radius: 1px;
  transition: var(--transition);
}

@media (max-width: 768px) {
  .nav-toggle { display: flex; }
  .nav-links {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    flex-direction: column;
    padding: 1.5rem;
    gap: 0;
    background: var(--bg-card);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: transform var(--transition), opacity var(--transition), visibility var(--transition);
  }
  .nav-links.is-open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }
  .nav-links li { width: 100%; }
  .nav-links a, .nav-links .theme-toggle {
    display: block;
    padding: 0.75rem 0;
    text-align: left;
  }
}

/* ========== Hero ========== */
.hero {
  position: relative;
  min-height: calc(100vh - var(--header-height));
  display: flex;
  align-items: center;
  padding: 3rem 0;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}
.hero-bg canvas {
  display: block;
  width: 100%;
  height: 100%;
  min-height: 400px;
  object-fit: cover;
}

.hero-content {
  position: relative;
  z-index: 1;
  text-align: center;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  margin: 0 0 0.75rem;
  letter-spacing: -0.02em;
}

.accent { color: var(--accent); }

.hero-desc {
  font-size: 1.125rem;
  color: var(--text-muted);
  margin: 0 0 1.5rem;
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}

.hero-btns {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  justify-content: center;
}

.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-sm);
  font-weight: 500;
  font-family: var(--font-sans);
  cursor: pointer;
  border: none;
  transition: transform var(--transition), box-shadow var(--transition);
}
.btn-primary {
  background: var(--accent);
  color: #fff;
}
.btn-primary:hover {
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: 0 6px 20px var(--accent-soft);
}
.btn-secondary {
  background: transparent;
  color: var(--accent);
  border: 2px solid var(--accent);
}
.btn-secondary:hover {
  background: var(--accent-soft);
  transform: translateY(-2px);
}

/* ========== Skills (Three.js) ========== */
.skills { padding: 4rem 0; }

.skills-wrap {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  align-items: center;
}
@media (min-width: 768px) {
  .skills-wrap { grid-template-columns: 1fr 1fr; gap: 2rem; }
}

.skills-canvas-wrap {
  position: relative;
  width: 100%;
  height: 280px;
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg);
  border: 1px solid var(--border);
}
.skills-canvas-wrap canvas { display: block; width: 100%; height: 100%; }

.skills-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}
.skills-list li {
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  border: 1px solid var(--border);
  font-weight: 500;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.skills-list li:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow);
}
.skills-list li {
  cursor: pointer;
}
.skills-list li:focus {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.skills-hint {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
  margin: -1rem 0 1rem;
}

/* 技能介紹浮層 */
.skill-modal {
  position: fixed;
  inset: 0;
  z-index: 110;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition), visibility var(--transition);
}
.skill-modal.is-open {
  opacity: 1;
  visibility: visible;
}

.skill-modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
}

.skill-modal-content {
  position: relative;
  width: 100%;
  max-width: 400px;
  max-height: 90vh;
  overflow-y: auto;
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  padding: 1.5rem;
}

.skill-modal-close {
  position: absolute;
  top: 0.75rem;
  right: 0.75rem;
  width: 36px;
  height: 36px;
  border: none;
  border-radius: var(--radius-sm);
  background: var(--bg);
  color: var(--text-muted);
  font-size: 1.5rem;
  line-height: 1;
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
}
.skill-modal-close:hover {
  background: var(--accent-soft);
  color: var(--accent);
}

.skill-modal-title {
  margin: 0 2rem 0.75rem 0;
  font-size: 1.35rem;
}

.skill-modal-image-wrap {
  width: 100%;
  aspect-ratio: 16/9;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--bg);
  margin-bottom: 1rem;
}
.skill-modal-image-wrap img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.skill-modal-desc {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.6;
}

/* ========== Projects / Cards ========== */
.projects { padding: 4rem 0; }

.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin: 0 0 2rem;
  text-align: center;
}

.cards {
  display: grid;
  /* 響應式欄位由 tailwind.css .tw-grid-cards 控制 */
  grid-template-columns: 1fr;
  gap: 1rem;
}
@media (min-width: 640px) {
  .cards { grid-template-columns: repeat(2, 1fr); gap: 1.25rem; }
}
@media (min-width: 1024px) {
  .cards { grid-template-columns: repeat(3, 1fr); gap: 1.5rem; }
}

.card {
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  display: flex;
  flex-direction: column;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.12);
}
[data-theme="dark"] .card:hover {
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.5);
}

.card-image {
  position: relative;
  height: 160px;
  background: linear-gradient(135deg, var(--accent, #6366f1) 0%, transparent 70%);
  opacity: 0.85;
}
.card-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
/* 未提供 img 時仍顯示漸層 */
.card-image:not(:has(img)) { background: linear-gradient(135deg, var(--accent, #6366f1) 0%, transparent 70%); }
.card-image:has(img) { background: none; }

.card-image.card-chart-wrap,
.card-chart-wrap {
  height: 160px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
  opacity: 1;
}
.card-image.card-chart-wrap { background: var(--bg); }
.card-chart-wrap canvas {
  width: 100% !important;
  height: 100% !important;
  display: block;
}

.card-body { padding: 1.25rem; flex: 1; display: flex; flex-direction: column; }

.card h3 {
  font-size: 1.2rem;
  margin: 0 0 0.5rem;
}

.card p {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin: 0 0 1rem;
  flex: 1;
}

.card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1rem;
}
.card-tags span {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.25rem 0.5rem;
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: 4px;
}

.card-link {
  font-weight: 500;
  display: inline-flex;
  align-items: center;
}
.card-link:hover { text-decoration: none; }
.card-demo { font-size: 0.9rem; }

/* 互動卡片 tilt：由 JS 設定 transform */
.card[data-tilt] {
  transform-style: preserve-3d;
  will-change: transform;
}
.card[data-tilt] .card-body { transform: translateZ(12px); }

/* ========== ML 專區（課程報告圖表互動版）========== */
.ml-showcase {
  padding: 3.5rem 0 4rem;
  background: linear-gradient(180deg, var(--bg) 0%, var(--bg-card) 8%, var(--bg) 100%);
  border-top: 1px solid var(--border);
}

.ml-showcase-title {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
}

.ml-showcase-badge {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.6rem;
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: 999px;
  letter-spacing: 0.02em;
}

.ml-showcase-desc {
  color: var(--text-muted);
  margin: 0 0 1.5rem;
  font-size: 0.95rem;
  max-width: 42rem;
}

.ml-narrative {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  margin-bottom: 2rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  opacity: 0.85;
  transition: opacity 0.3s ease, box-shadow 0.3s ease;
}

.ml-narrative.ml-narrative-active {
  opacity: 1;
  box-shadow: 0 4px 24px var(--accent-soft);
}

.ml-narrative-avatar {
  flex-shrink: 0;
  font-size: 1.5rem;
  line-height: 1;
}

.ml-narrative-text {
  margin: 0;
  font-size: 0.9rem;
  color: var(--text);
  line-height: 1.5;
}

.ml-charts {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
}

@media (min-width: 640px) {
  .ml-charts {
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem 1.5rem;
  }
  .ml-chart-block.full-width { grid-column: 1 / -1; }
}

@media (min-width: 1024px) {
  .ml-charts { gap: 2.5rem 2rem; }
}

.ml-chart-block {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  box-shadow: var(--shadow);
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.5s ease;
}

.ml-chart-block.ml-visible {
  opacity: 1;
  transform: translateY(0);
}

.ml-chart-block.ml-animate:nth-child(1) { transition-delay: 0.05s; }
.ml-chart-block.ml-animate:nth-child(2) { transition-delay: 0.1s; }
.ml-chart-block.ml-animate:nth-child(3) { transition-delay: 0.15s; }
.ml-chart-block.ml-animate:nth-child(4) { transition-delay: 0.2s; }
.ml-chart-block.ml-animate:nth-child(5) { transition-delay: 0.25s; }
.ml-chart-block.ml-animate:nth-child(6) { transition-delay: 0.3s; }

.ml-chart-title {
  margin: 0 0 1rem;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
}

.ml-chart-wrap {
  position: relative;
  min-height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.ml-chart-wrap canvas {
  max-width: 100%;
  height: auto !important;
}

.ml-chart-confusion .ml-chart-wrap { min-height: 220px; }
.ml-chart-curves .ml-chart-wrap { min-height: 220px; }
.ml-chart-feature .ml-chart-wrap { min-height: 260px; }
.ml-chart-heatmap .ml-chart-wrap { min-height: 260px; }
.ml-chart-pca .ml-chart-wrap { min-height: 260px; }

.ml-chart-caption {
  margin: 0.75rem 0 0;
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ========== GPU 專區（CUDA 學習 + 作品集）========== */
.gpu-showcase {
  padding: 3.5rem 0 4rem;
  background: linear-gradient(180deg, var(--bg) 0%, var(--bg-card) 8%, var(--bg) 100%);
  border-top: 1px solid var(--border);
}

.gpu-showcase-title {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
}

.gpu-showcase-badge {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.6rem;
  background: rgba(118, 185, 0, 0.2);
  color: #76b900;
  border-radius: 999px;
  letter-spacing: 0.02em;
}

[data-theme="dark"] .gpu-showcase-badge {
  background: rgba(118, 185, 0, 0.25);
  color: #9ade2e;
}

.gpu-showcase-desc {
  color: var(--text-muted);
  margin: 0 0 1.5rem;
  font-size: 0.95rem;
  max-width: 42rem;
}

.gpu-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.gpu-stack-item {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  padding: 0.3rem 0.6rem;
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: 6px;
}

.gpu-table-wrap {
  overflow-x: auto;
  margin-bottom: 1.5rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}

.gpu-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.gpu-table th,
.gpu-table td {
  padding: 0.75rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.gpu-table th {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 600;
}

.gpu-table tbody tr:last-child td {
  border-bottom: none;
}

.gpu-table tbody tr:hover {
  background: var(--accent-soft);
}

.gpu-table-caption {
  margin: 0.5rem 1rem 0.75rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.gpu-reproduce-hint {
  margin: 0 0 1rem;
  font-size: 0.875rem;
  color: var(--text-muted);
}

.gpu-reproduce-hint code {
  font-family: var(--font-mono);
  font-size: 0.8em;
  padding: 0.15rem 0.4rem;
  background: var(--bg-card);
  border-radius: 4px;
  border: 1px solid var(--border);
}

.gpu-actions {
  margin-top: 1rem;
}

.gpu-actions .btn {
  display: inline-block;
}

/* ========== ML 專區（人工智慧 × 資料科學 互動圖表）========== */
.ml-showcase {
  padding: 3.5rem 0 4rem;
  background: var(--bg);
  position: relative;
  overflow: hidden;
}
.ml-showcase-title {
  position: relative;
  display: inline-flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 0.75rem;
}
.ml-showcase-badge {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.25rem 0.6rem;
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: 999px;
  animation: ml-badge-pulse 2s ease-in-out infinite;
}
@keyframes ml-badge-pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.9; transform: scale(1.02); }
}
.ml-showcase-desc {
  color: var(--text-muted);
  margin: 0.5rem 0 1.5rem;
  max-width: 42rem;
  line-height: 1.6;
}
.ml-narrative {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  margin-bottom: 2rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  transition: opacity 0.35s ease, transform 0.35s ease;
}
.ml-narrative-avatar {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent-soft) 0%, rgba(99, 102, 241, 0.2) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
}
.ml-narrative-text {
  margin: 0;
  font-size: 0.95rem;
  color: var(--text);
  line-height: 1.5;
}
.ml-charts {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}
@media (min-width: 640px) {
  .ml-charts { grid-template-columns: repeat(2, 1fr); gap: 1.75rem; }
}
@media (min-width: 1024px) {
  .ml-charts { grid-template-columns: repeat(2, 1fr); gap: 2rem; }
}
.ml-chart-block.full-width {
  grid-column: 1 / -1;
}
.ml-chart-block {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}
.ml-chart-block:hover {
  box-shadow: 0 8px 28px rgba(0, 0, 0, 0.1);
  border-color: var(--accent);
}
[data-theme="dark"] .ml-chart-block:hover {
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.35);
}
.ml-chart-title {
  font-size: 1.05rem;
  margin: 0 0 0.75rem;
  color: var(--text);
  font-weight: 600;
}
.ml-chart-wrap {
  position: relative;
  width: 100%;
  min-height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.ml-chart-wrap canvas {
  max-width: 100%;
  height: auto;
}
.ml-chart-confusion { min-height: 240px; aspect-ratio: 1.2; }
.ml-chart-curves { min-height: 220px; height: 220px; }
.ml-chart-feature { min-height: 280px; height: 280px; }
.ml-chart-heatmap { min-height: 260px; aspect-ratio: 1; }
.ml-chart-pca { min-height: 260px; height: 260px; }
.ml-chart-caption {
  margin: 0.75rem 0 0;
  font-size: 0.8rem;
  color: var(--text-muted);
}
/* 捲動進入視窗時淡入＋上移 */
.ml-chart-block.ml-animate {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.5s ease, transform 0.5s ease, box-shadow var(--transition), border-color var(--transition);
}
.ml-chart-block.ml-animate.is-visible {
  opacity: 1;
  transform: translateY(0);
}
.ml-chart-block.ml-animate:nth-child(1) { transition-delay: 0s; }
.ml-chart-block.ml-animate:nth-child(2) { transition-delay: 0.08s; }
.ml-chart-block.ml-animate:nth-child(3) { transition-delay: 0.16s; }
.ml-chart-block.ml-animate:nth-child(4) { transition-delay: 0.24s; }
.ml-chart-block.ml-animate:nth-child(5) { transition-delay: 0.32s; }
.ml-chart-block.ml-animate:nth-child(6) { transition-delay: 0.4s; }

/* ========== Contact ========== */
.contact { padding: 3rem 0; text-align: center; }
.contact-desc { color: var(--text-muted); margin: 0; }

/* ========== Footer ========== */
.footer {
  padding: 1.5rem;
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* ========== Chat FAB ========== */
.chat-fab {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  z-index: 90;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  border: none;
  background: var(--accent);
  color: #fff;
  font-size: 1.5rem;
  cursor: pointer;
  box-shadow: 0 4px 20px var(--accent-soft);
  transition: transform var(--transition), box-shadow var(--transition);
}
.chat-fab:hover {
  transform: scale(1.08);
  box-shadow: 0 6px 24px var(--accent-soft);
}

.chat-fab-icon { display: block; line-height: 1; }

/* ========== Chat Panel ========== */
.chat-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  z-index: 95;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition), visibility var(--transition);
}
.chat-overlay.is-open {
  opacity: 1;
  visibility: visible;
}

.chat-panel {
  position: fixed;
  bottom: 0;
  right: 0;
  z-index: 99;
  width: 100%;
  max-width: 400px;
  height: 500px;
  max-height: 85vh;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius) var(--radius) 0 0;
  box-shadow: 0 -4px 32px rgba(0, 0, 0, 0.15);
  display: flex;
  flex-direction: column;
  transform: translateY(100%);
  opacity: 0;
  visibility: hidden;
  transition: transform var(--transition), opacity var(--transition), visibility var(--transition);
}
.chat-panel.is-open {
  transform: translateY(0);
  opacity: 1;
  visibility: visible;
}

.chat-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
}
.chat-header h3 { margin: 0; font-size: 1rem; }

.chat-close {
  width: 36px;
  height: 36px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-muted);
  font-size: 1.5rem;
  line-height: 1;
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
}
.chat-close:hover { background: var(--accent-soft); color: var(--accent); }

.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.msg {
  display: flex;
  gap: 0.75rem;
  max-width: 90%;
  align-items: flex-start;
}
.msg-user { align-self: flex-end; flex-direction: row-reverse; }
.msg-user p {
  background: var(--accent);
  color: #fff;
  border-radius: var(--radius-sm) var(--radius-sm) 0 var(--radius-sm);
}
.msg-bot p {
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm) var(--radius-sm) var(--radius-sm) 0;
}
.msg-typing p { color: var(--text-muted); }
.msg-typing p::after { content: '…'; animation: typing 1s steps(3) infinite; }
@keyframes typing { 0%, 100% { opacity: 0.3; } 50% { opacity: 1; } }

.msg-avatar {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}

.msg p {
  margin: 0;
  padding: 0.75rem 1rem;
  font-size: 0.9rem;
  line-height: 1.5;
}

.chat-form {
  display: flex;
  gap: 0.5rem;
  padding: 1rem;
  border-top: 1px solid var(--border);
  background: var(--bg-card);
}

.chat-input {
  flex: 1;
  padding: 0.75rem 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  background: var(--bg);
  color: var(--text);
  transition: border-color var(--transition);
}
.chat-input::placeholder { color: var(--text-muted); }
.chat-input:focus {
  outline: none;
  border-color: var(--accent);
}

.chat-send {
  padding: 0.75rem 1rem;
  border: none;
  border-radius: var(--radius-sm);
  background: var(--accent);
  color: #fff;
  font-weight: 500;
  cursor: pointer;
  transition: opacity var(--transition), transform var(--transition);
}
.chat-send:hover { opacity: 0.9; transform: scale(1.02); }

@media (min-width: 769px) {
  .chat-panel {
    bottom: 1.5rem;
    right: 1.5rem;
    border-radius: var(--radius);
    height: 520px;
  }
  .chat-panel.is-open { transform: translateY(0) translateX(0); }
}