/* ═══════════════════════════════════════════════════════════
   APM PORTFOLIO — style.css
   Stack: Bootstrap 5 + vanilla CSS
   ═══════════════════════════════════════════════════════════ */

/* ── Google Fonts ── */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Montserrat:wght@400;700&display=swap');

/* ── Smooth Scroll ── */
html {
  scroll-behavior: smooth;
  scroll-padding-top: 90px;
}

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

/* ── CSS Variables ── */
:root {
  --primary: #2563EB;
  --primary-light: #3B82F6;
  --primary-dark: #1D4ED8;
  --accent: #10B981;
  --surface: #F8FAFC;
  --surface-2: #F1F5F9;
  --surface-light: #ffffff;
  --header-bg: rgba(248, 250, 252, 0.95);
  --border: #E2E8F0;
  --text: #0F172A;
  --text-2: #475569;
  --text-3: #94A3B8;
  --badge-bg: #EFF6FF;
  --success-bg: #F0FDF4;
  --code-bg: #E0E7FF;
  --code-text: #3730A3;
  --card-shadow: 0 1px 3px rgba(0,0,0,.07), 0 4px 12px rgba(0,0,0,.05);
  --card-shadow-hover: 0 4px 16px rgba(37,99,235,.15), 0 8px 24px rgba(0,0,0,.08);
  --radius: 12px;
  --transition: 0.25s cubic-bezier(0.4,0,0.2,1);
}

[data-theme="dark"] {
  --primary: #3B82F6;
  --primary-light: #60A5FA;
  --primary-dark: #2563EB;
  --accent: #10B981;
  --surface: #0F172A;
  --surface-2: #334155;
  --surface-light: #1E293B;
  --header-bg: rgba(15, 23, 42, 0.95);
  --border: #334155;
  --text: #F8FAFC;
  --text-2: #CBD5E1;
  --text-3: #94A3B8;
  --badge-bg: rgba(59, 130, 246, 0.15);
  --success-bg: rgba(16, 185, 129, 0.15);
  --code-bg: rgba(59, 130, 246, 0.2);
  --code-text: #F8FAFC;
  --card-shadow: 0 4px 14px rgba(0,0,0,0.4);
  --card-shadow-hover: 0 10px 25px rgba(0,0,0,0.6);
}

/* ── Base ── */
body {
  padding-top: 80px;
  font-family: 'Inter', sans-serif;
  font-size: 0.97rem;
  line-height: 1.7;
  background-color: var(--surface);
  color: var(--text);
}

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

/* ── Progress Bar ── */
.progress-container {
  width: 100%;
  height: 3px;
  background: transparent;
}
.progress-bar {
  height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  width: 0%;
  transition: width 0.1s linear;
}

/* ══════════════════════════════════════════════════════════
   HEADER / NAV
══════════════════════════════════════════════════════════ */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: var(--header-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 20px;
}

.navbar-brand h1 {
  font-family: 'Montserrat', sans-serif;
  font-size: 1.45rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 1px;
}
.navbar-brand p {
  font-size: 0.78rem;
  color: var(--text-2);
  font-weight: 500;
  letter-spacing: 0.02em;
}

.navbar-toggler { border: none; box-shadow: none; }

.nav-menu a.nav-link {
  color: var(--text-2);
  font-size: 0.875rem;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: 6px;
  transition: background var(--transition), color var(--transition);
}
.nav-menu a.nav-link:hover {
  color: var(--primary);
  background: var(--badge-bg);
  text-decoration: none;
}

/* ══════════════════════════════════════════════════════════
   LAYOUT
══════════════════════════════════════════════════════════ */
.container {
  width: 92%;
  max-width: 1060px;
  margin: 0 auto;
  padding: 20px 16px;
}

main { margin-top: 12px; }

section {
  margin-bottom: 72px;
}

section h2 {
  font-family: 'Montserrat', sans-serif;
  font-size: 1.65rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 6px;
  border-bottom: 3px solid var(--primary);
  display: inline-block;
  padding-bottom: 4px;
}

.section-sub {
  color: var(--text-2);
  font-size: 0.9rem;
  margin-top: 4px;
  margin-bottom: 0;
}

/* ── Reveal animation ── */
.reveal {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Fade-in for main ── */
.fade-in {
  animation: fadeIn 0.8s ease forwards;
}
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ══════════════════════════════════════════════════════════
   HERO SECTION
══════════════════════════════════════════════════════════ */
.hero-section {
  padding: 60px 0 48px;
  margin-bottom: 60px;
  border-bottom: 1px solid var(--border);
}

.hero-badge {
  display: inline-block;
  background: var(--badge-bg);
  color: var(--primary);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 5px 14px;
  border-radius: 50px;
  margin-bottom: 18px;
  border: 1px solid #BFDBFE;
}

.hero-headline {
  font-family: 'Montserrat', sans-serif;
  font-size: clamp(1.7rem, 4vw, 2.5rem);
  font-weight: 700;
  line-height: 1.25;
  color: var(--text);
  margin-bottom: 18px;
  max-width: 700px;
}

.hero-highlight {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-sub {
  font-size: 1rem;
  color: var(--text-2);
  max-width: 620px;
  margin-bottom: 24px;
  line-height: 1.7;
}

.hero-socials {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 28px;
}
.hero-socials a {
  color: var(--text-2);
  transition: color var(--transition), transform var(--transition);
}
.hero-socials a:hover {
  color: var(--primary);
  transform: translateY(-2px);
}
.hero-socials i { font-size: 28px; }

.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}

.btn-primary-cta {
  background: var(--primary);
  color: #fff;
  padding: 11px 26px;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
  display: inline-block;
}
.btn-primary-cta:hover {
  background: var(--primary-dark);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(37,99,235,0.3);
}

.btn-secondary-cta {
  background: transparent;
  color: var(--primary);
  padding: 11px 26px;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  border: 1.5px solid var(--primary);
  transition: background var(--transition), color var(--transition), transform var(--transition);
  display: inline-block;
}
.btn-secondary-cta:hover {
  background: var(--badge-bg);
  color: var(--primary-dark);
  transform: translateY(-2px);
}

.btn-resume-hero {
  background: transparent;
  color: var(--text-2);
  padding: 11px 22px;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 500;
  border: 1px solid var(--border);
  transition: background var(--transition), color var(--transition);
  display: inline-block;
}
.btn-resume-hero:hover {
  background: var(--surface-2);
  color: var(--text);
}
.btn-resume-hero i { margin-right: 6px; }

/* ══════════════════════════════════════════════════════════
   METRIC CARDS
══════════════════════════════════════════════════════════ */
.metric-card {
  background: var(--surface-light);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 20px 20px;
  text-align: center;
  box-shadow: var(--card-shadow);
  transition: transform var(--transition), box-shadow var(--transition);
  height: 100%;
}
.metric-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--card-shadow-hover);
}
.metric-icon {
  font-size: 1.8rem;
  margin-bottom: 8px;
}
.metric-value {
  font-family: 'Montserrat', sans-serif;
  font-size: 2.2rem;
  font-weight: 700;
  color: var(--primary);
  line-height: 1;
  margin-bottom: 6px;
}
.metric-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 4px;
}
.metric-context {
  font-size: 0.75rem;
  color: var(--text-3);
}

/* ══════════════════════════════════════════════════════════
   CASE STUDY CARDS
══════════════════════════════════════════════════════════ */
.case-card {
  background: var(--surface-light);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--card-shadow);
  overflow: hidden;
  transition: box-shadow var(--transition);
}
.case-card:hover { box-shadow: var(--card-shadow-hover); }

.case-card-header {
  padding: 24px 26px 20px;
}

.case-meta {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 12px;
}
.case-logo {
  width: 44px;
  height: 44px;
  object-fit: contain;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #ffffff !important;
  padding: 4px;
  flex-shrink: 0;
}
.case-company {
  display: block;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.case-period {
  display: block;
  font-size: 0.78rem;
  color: var(--text-3);
  margin-top: 1px;
}

.case-title {
  font-family: 'Montserrat', sans-serif;
  font-size: 1.12rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 12px;
}

.case-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin-bottom: 16px;
}
.tag {
  background: var(--badge-bg);
  color: var(--primary);
  border: 1px solid #BFDBFE;
  font-size: 0.72rem;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 50px;
}

.case-toggle-btn {
  background: transparent;
  border: 1.5px solid var(--primary);
  color: var(--primary);
  font-size: 0.84rem;
  font-weight: 600;
  padding: 8px 38px 8px 18px;
  border-radius: 7px;
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  position: relative;
  min-width: 172px;
}
.case-toggle-btn:hover {
  background: var(--primary);
  color: #fff;
}
.case-toggle-btn .fa {
  position: absolute;
  right: 14px;
  transition: transform var(--transition);
  font-size: 0.8rem;
}
.case-toggle-btn.open .fa { transform: rotate(180deg); }

/* ── Case body (expandable content) ── */
.case-body {
  padding: 0 26px 26px;
  border-top: 1px solid var(--border);
  margin-top: 4px;
  padding-top: 22px;
}

.case-section {
  margin-bottom: 22px;
}
.case-section h4 {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.case-section-icon { font-size: 1rem; }

.case-section p,
.case-section li {
  font-size: 0.9rem;
  color: var(--text-2);
}
.case-section ul { padding-left: 18px; }
.case-section ul li { margin-bottom: 5px; }

.impact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(110px, 1fr));
  gap: 12px;
  margin-top: 6px;
}
.impact-item {
  background: linear-gradient(135deg, var(--badge-bg), var(--success-bg));
  border: 1px solid #BFDBFE;
  border-radius: 8px;
  padding: 14px 10px;
  text-align: center;
}
.impact-item strong {
  display: block;
  font-family: 'Montserrat', sans-serif;
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--primary);
}
.impact-item span {
  font-size: 0.75rem;
  color: var(--text-2);
  font-weight: 500;
}

/* ══════════════════════════════════════════════════════════
   FEATURED PROJECT CARDS
══════════════════════════════════════════════════════════ */
.project-card {
  background: var(--surface-light);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--card-shadow);
  transition: transform var(--transition), box-shadow var(--transition);
  height: 100%;
  display: flex;
  flex-direction: column;
}
.project-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--card-shadow-hover);
}

.project-card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 12px;
}
.project-icon {
  font-size: 1.8rem;
  line-height: 1;
}
.project-metric-badge {
  background: var(--success-bg);
  border: 1px solid #A7F3D0;
  color: #059669;
  font-size: 0.7rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 50px;
  text-align: right;
  max-width: 60%;
}

.project-title {
  font-family: 'Montserrat', sans-serif;
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 7px;
}
.project-problem {
  font-size: 0.83rem;
  color: var(--text-2);
  font-style: italic;
  margin-bottom: 14px;
  flex: 1;
}

.project-toggle-btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-2);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 7px 34px 7px 14px;
  border-radius: 6px;
  cursor: pointer;
  transition: all var(--transition);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  position: relative;
  min-width: 148px;
  align-self: flex-start;
}
.project-toggle-btn:hover {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}
.project-toggle-btn .fa {
  position: absolute;
  right: 11px;
  transition: transform var(--transition);
  font-size: 0.75rem;
}
.project-toggle-btn.open .fa { transform: rotate(180deg); }

.nested-toggle-btn {
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 0.85rem;
  font-weight: 600;
  padding: 10px 14px;
  cursor: pointer;
  transition: all var(--transition);
}
.nested-toggle-btn:hover {
  background: var(--surface-2);
  color: var(--primary);
}
.nested-toggle-btn .fa {
  transition: transform var(--transition);
  color: var(--text-3);
}
.nested-toggle-btn.open {
  background: var(--surface-2);
  border-bottom-left-radius: 0;
  border-bottom-right-radius: 0;
}
.nested-toggle-btn.open .fa {
  transform: rotate(180deg);
}

.project-detail {
  margin-top: 0;
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--text);
}

.nested-detail-box {
  background: var(--surface-2);
  border: 1px solid var(--border) !important;
  border-top: none !important;
  border-radius: 0 0 8px 8px;
}
.project-detail p { margin-bottom: 8px; }

.project-link {
  color: var(--primary);
  font-weight: 600;
  font-size: 0.83rem;
}
.project-link:hover { text-decoration: underline; }

/* ══════════════════════════════════════════════════════════
   EXPERIMENTATION CARDS
══════════════════════════════════════════════════════════ */
.exp-card {
  background: var(--surface-light);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--card-shadow);
  transition: transform var(--transition), box-shadow var(--transition);
  height: 100%;
}
.exp-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--card-shadow-hover);
}
.exp-icon {
  font-size: 1.8rem;
  margin-bottom: 10px;
}
.exp-card h5 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 8px;
}
.exp-card p {
  font-size: 0.85rem;
  color: var(--text-2);
  margin-bottom: 14px;
}

.exp-toggle-btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-2);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 7px 34px 7px 14px;
  border-radius: 6px;
  cursor: pointer;
  transition: all var(--transition);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  position: relative;
  min-width: 125px;
}
.exp-toggle-btn .fa {
  position: absolute;
  right: 12px;
}
.exp-toggle-btn:hover {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}
.exp-toggle-btn .fa {
  font-size: 0.8rem;
}

.exp-detail {
  margin-top: 14px;
  padding: 14px;
  background: var(--surface-2);
  border-radius: 8px;
  font-size: 0.84rem;
  color: var(--text-2);
}
.exp-detail ol, .exp-detail ul {
  padding-left: 17px;
}
.exp-detail li { margin-bottom: 6px; }
.exp-detail p { margin-bottom: 8px; }
.exp-detail code {
  background: var(--code-bg);
  color: var(--code-text);
  padding: 4px 10px;
  border-radius: 5px;
  font-size: 0.82rem;
  display: block;
  overflow-x: auto;
}

/* ══════════════════════════════════════════════════════════
   EXPERIENCE ROLE CARDS
══════════════════════════════════════════════════════════ */
.exp-role-card {
  background: var(--surface-light);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--card-shadow);
  margin-bottom: 24px;
  overflow: hidden;
  transition: box-shadow var(--transition);
}
.exp-role-card:hover { box-shadow: var(--card-shadow-hover); }

.exp-role-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 24px;
  background: var(--surface-2);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
  gap: 10px;
}

.exp-role-left {
  display: flex;
  align-items: center;
  gap: 14px;
}

.exp-role-logo {
  width: 44px;
  height: 44px;
  object-fit: contain;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #ffffff !important;
  padding: 4px;
  flex-shrink: 0;
}

.exp-role-title {
  font-size: 0.97rem;
  font-weight: 700;
  color: var(--text);
}

.exp-role-company {
  font-size: 0.8rem;
  color: var(--primary);
  font-weight: 600;
  margin-top: 1px;
}

.exp-role-period {
  font-size: 0.78rem;
  color: var(--text-3);
  font-weight: 500;
  white-space: nowrap;
}

/* ── Role body ── */
.exp-role-body {
  padding: 22px 24px 20px;
}

.exp-role-summary {
  font-size: 0.9rem;
  color: var(--text-2);
  margin-bottom: 20px;
  line-height: 1.65;
}

/* ── 3-column layout ── */
.exp-role-cols {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-bottom: 20px;
}

.exp-role-col-title {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 8px;
  letter-spacing: 0.01em;
}

.exp-role-col ul {
  padding-left: 16px;
  margin: 0;
}

.exp-role-col li {
  font-size: 0.83rem;
  color: var(--text-2);
  margin-bottom: 7px;
  line-height: 1.55;
}

/* ── Stack tags (tech pills) ── */
.exp-role-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin-bottom: 16px;
  padding-top: 14px;
  border-top: 1px solid var(--border);
}

.exp-stack-tag {
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text-2);
  font-size: 0.72rem;
  font-weight: 600;
  padding: 4px 11px;
  border-radius: 50px;
}

/* ── Impact chips ── */
.exp-role-impact {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.exp-impact-chip {
  background: linear-gradient(135deg, var(--badge-bg), var(--success-bg));
  border: 1px solid #BFDBFE;
  color: var(--primary-dark);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 5px 13px;
  border-radius: 50px;
}

a.exp-impact-chip {
  text-decoration: none;
  display: inline-block;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
a.exp-impact-chip:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  color: var(--primary-dark);
}

/* ══════════════════════════════════════════════════════════
   PRINCIPLE CARDS
══════════════════════════════════════════════════════════ */
.principle-card {
  background: var(--surface-light);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--card-shadow);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  height: 100%;
  position: relative;
}
.principle-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--card-shadow-hover);
  border-color: #BFDBFE;
}

.principle-num {
  font-family: 'Montserrat', sans-serif;
  font-size: 2rem;
  font-weight: 700;
  color: #BFDBFE;
  line-height: 1;
  margin-bottom: 8px;
}

.principle-card h5 {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 8px;
}
.principle-card p {
  font-size: 0.84rem;
  color: var(--text-2);
  margin: 0;
}

/* ══════════════════════════════════════════════════════════
   EDUCATION / GENERIC CARDS
══════════════════════════════════════════════════════════ */
.education-logo {
  max-width: 8rem;
  height: 8rem;
  display: block;
  margin: 15px auto 10px;
  object-fit: contain;
  background: #ffffff !important;
  border-radius: 8px;
  padding: 8px;
  border: 1px solid var(--border);
}

.card {
  background: var(--surface-light);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: transform var(--transition), box-shadow var(--transition);
  box-shadow: var(--card-shadow);
  color: var(--text);
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--card-shadow-hover);
}

.list-group-item {
  background: var(--surface-light);
  border-color: var(--border);
  color: var(--text);
}

.text-muted {
  color: var(--text-3) !important;
}

/* ── Btn-resume (legacy, keep for resume page) ── */
.btn-resume {
  background: var(--surface-light);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 9px 20px;
  border-radius: 7px;
  font-size: 0.9rem;
  transition: background var(--transition), transform var(--transition);
  display: inline-block;
}
.btn-resume:hover {
  background: var(--surface-2);
  transform: translateY(-2px);
}
.btn-resume i { margin-right: 7px; }

/* ══════════════════════════════════════════════════════════
   FOOTER
══════════════════════════════════════════════════════════ */
footer {
  background: var(--surface-light);
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: 0.875rem;
  color: var(--text-2);
  padding: 28px 0;
}

/* ── Theme Toggle ── */
.theme-toggle {
  background: transparent;
  border: none;
  color: var(--text-2);
  font-size: 1.25rem;
  cursor: pointer;
  padding: 6px;
  border-radius: 50px;
  transition: transform var(--transition), color var(--transition), background var(--transition);
}
.theme-toggle:hover {
  color: var(--primary);
  background: var(--surface-2);
  transform: scale(1.05);
}

/* ── Copy Tooltip ── */
.copy-trigger {
  position: relative;
  transition: color var(--transition);
  cursor: pointer;
}
.copy-trigger:hover { color: var(--primary) !important; }
.copy-trigger::after {
  content: "Copied!";
  position: absolute;
  bottom: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(5px);
  background: #10B981;
  color: #fff;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 4px 8px;
  border-radius: 4px;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s ease, transform 0.3s ease, visibility 0.3s ease;
  pointer-events: none;
  white-space: nowrap;
}
.copy-trigger.copied::after {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(-5px);
}

/* ── Read Meta Data ── */
.read-metadata {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text-3);
  background: var(--surface-2);
  padding: 3px 8px;
  border-radius: 50px;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  white-space: nowrap;
}
footer p { margin-bottom: 6px; }
.copyright { margin-bottom: 0; color: var(--text-3); font-size: 0.8rem; }

/* ══════════════════════════════════════════════════════════
   BACK TO TOP
══════════════════════════════════════════════════════════ */
#backToTop {
  position: fixed;
  bottom: 28px;
  right: 28px;
  width: 42px;
  height: 42px;
  background: var(--primary);
  border: none;
  border-radius: 10px;
  color: #fff;
  font-size: 22px;
  line-height: 42px;
  text-align: center;
  cursor: pointer;
  box-shadow: 0 4px 14px rgba(37,99,235,0.35);
  transition: opacity 0.4s ease, visibility 0.4s ease, transform var(--transition);
  opacity: 0;
  visibility: hidden;
  z-index: 999;
}
#backToTop.show { opacity: 1; visibility: visible; }
#backToTop:hover { transform: scale(1.08); }

/* ── Return to Context Button ── */
.return-context-wrapper {
  position: fixed;
  bottom: 24px;
  left: 24px;
  display: flex;
  align-items: center;
  background: var(--surface-light);
  border: 1px solid var(--border);
  border-radius: 50px;
  box-shadow: 0 4px 14px rgba(0,0,0,0.08);
  transition: opacity 0.4s ease, visibility 0.4s ease, transform 0.3s ease;
  z-index: 999;
  opacity: 0;
  visibility: hidden;
  transform: translateY(15px);
}
.return-context-wrapper.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.return-context-wrapper.hide-anim {
  opacity: 0;
  visibility: hidden;
  transform: translateY(15px);
  pointer-events: none;
}
.return-context-main {
  background: transparent;
  border: none;
  color: var(--text-2);
  font-size: 0.82rem;
  font-weight: 600;
  padding: 8px 14px 8px 16px;
  border-radius: 50px 0 0 50px;
  cursor: pointer;
  transition: color var(--transition), background var(--transition);
}
.return-context-main:hover {
  color: var(--primary-dark);
  background: var(--surface-2);
}
.return-context-close {
  background: transparent;
  border: none;
  border-left: 1px solid var(--border);
  color: var(--text-3);
  font-size: 1.2rem;
  padding: 6px 14px;
  cursor: pointer;
  border-radius: 0 50px 50px 0;
  transition: color var(--transition), background var(--transition);
  display: flex;
  align-items: center;
}
.return-context-close:hover {
  color: #ef4444;
  background: var(--surface-2);
}

/* ══════════════════════════════════════════════════════════
   SOCIAL ICONS
══════════════════════════════════════════════════════════ */
.social {
  margin: 10px 0;
  padding: 8px 0;
}

/* ══════════════════════════════════════════════════════════
   RESPONSIVE
══════════════════════════════════════════════════════════ */
@media (max-width: 992px) {
  .exp-role-cols { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  body { padding-top: 100px; }

  .hero-section { padding: 36px 0 32px; }
  .hero-headline { font-size: 1.55rem; }

  .hero-ctas { gap: 10px; }
  .btn-primary-cta, .btn-secondary-cta, .btn-resume-hero {
    padding: 9px 18px;
    font-size: 0.84rem;
  }

  .metric-value { font-size: 1.8rem; }

  .case-card-header { padding: 18px 18px 16px; }
  .case-body { padding: 0 18px 20px; padding-top: 18px; }

  .impact-grid { grid-template-columns: repeat(3, 1fr); }

  .principle-card { margin-bottom: 0; }

  .header-container { padding: 10px 16px; }

  .exp-role-cols { grid-template-columns: 1fr; }
  .exp-role-header { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 480px) {
  .impact-grid { grid-template-columns: repeat(2, 1fr); }
  section h2 { font-size: 1.4rem; }
}
/* Accordion Expand Animation */
@keyframes slideDownFade {
  from {
    opacity: 0;
    transform: translateY(-8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideUpFade {
  from {
    opacity: 1;
    transform: translateY(0);
  }
  to {
    opacity: 0;
    transform: translateY(-8px);
  }
}

.project-detail, .case-body, .exp-detail {
  animation: slideDownFade 0.35s ease-out forwards;
}
.closing {
  animation: slideUpFade 0.34s ease-out forwards !important;
}

/* ── Target Highlight Pulse ── */
@keyframes targetHighlightPulse {
  0% { box-shadow: var(--card-shadow); border-color: var(--border); }
  35% { box-shadow: 0 0 0 6px rgba(59, 130, 246, 0.4); border-color: var(--primary); }
  100% { box-shadow: var(--card-shadow); border-color: var(--border); }
}

.highlight-target {
  animation: targetHighlightPulse 1.8s ease-out;
}