/* ---------- Design tokens ---------- */
:root {
  --bg: #0b0f19;
  --bg-alt: #10151f;
  --surface: #141a26;
  --surface-2: #1b2231;
  --border: #232b3d;
  --text: #eef1f7;
  --text-dim: #a3adc2;
  --text-faint: #6b7488;
  --accent: #4fd1c5;
  --accent-2: #7c9cff;
  --accent-contrast: #06110f;
  --success: #4fd18a;
  --danger: #ff6b6b;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;
  --shadow: 0 20px 50px -20px rgba(0,0,0,0.5);
  --header-h: 72px;
  --max-w: 1120px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
}

:root[data-theme="light"] {
  --bg: #f7f8fb;
  --bg-alt: #ffffff;
  --surface: #ffffff;
  --surface-2: #f0f2f7;
  --border: #e3e7ef;
  --text: #131826;
  --text-dim: #4d5567;
  --text-faint: #8991a5;
  --accent: #0f9c8f;
  --accent-2: #4c63d2;
  --accent-contrast: #ffffff;
  --shadow: 0 20px 50px -20px rgba(20,30,60,0.18);
}

@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) {
    --bg: #f7f8fb;
    --bg-alt: #ffffff;
    --surface: #ffffff;
    --surface-2: #f0f2f7;
    --border: #e3e7ef;
    --text: #131826;
    --text-dim: #4d5567;
    --text-faint: #8991a5;
    --accent: #0f9c8f;
    --accent-2: #4c63d2;
    --accent-contrast: #ffffff;
    --shadow: 0 20px 50px -20px rgba(20,30,60,0.18);
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

/* ---------- Accessibility ---------- */
.skip-link {
  position: fixed;
  top: -60px;
  left: 16px;
  z-index: 2000;
  background: var(--accent);
  color: var(--accent-contrast);
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 0.9rem;
  transition: top 0.2s ease;
}
.skip-link:focus { top: 16px; }

a:focus-visible,
button:focus-visible,
input:focus-visible,
textarea:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background 0.25s ease, color 0.25s ease;
}

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

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

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

/* ---------- Progress bar ---------- */
.progress-bar {
  position: fixed;
  top: 0; left: 0;
  height: 3px;
  width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  z-index: 1000;
  transition: width 0.1s ease-out;
}

/* ---------- Header ---------- */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-h);
  z-index: 900;
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  backdrop-filter: blur(14px) saturate(140%);
  border-bottom: 1px solid transparent;
  transition: border-color 0.25s ease, background 0.25s ease;
}
.site-header.scrolled { border-bottom-color: var(--border); }

.nav {
  height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.logo {
  font-size: 1.3rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.logo-dot { color: var(--accent); }

.nav-links {
  list-style: none;
  display: flex;
  align-items: center;
  gap: 30px;
  margin: 0;
  padding: 0;
}
.nav-links a {
  font-size: 0.94rem;
  color: var(--text-dim);
  font-weight: 500;
  transition: color 0.2s ease;
  position: relative;
}
.nav-links a:hover { color: var(--text); }
.nav-links a[data-nav-link]::after {
  content: "";
  position: absolute;
  left: 0; bottom: -6px;
  width: 100%;
  height: 2px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.25s ease;
}
.nav-links a[data-nav-link].active { color: var(--text); }
.nav-links a[data-nav-link].active::after { transform: scaleX(1); }
.nav-links a.nav-cta {
  color: var(--accent-contrast);
  background: var(--accent);
  padding: 9px 18px;
  border-radius: 100px;
  font-weight: 600;
}
.nav-links a.nav-cta:hover { opacity: 0.9; color: var(--accent-contrast); }
.nav-links a.nav-cta::after { display: none; }

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  background: none;
  border: none;
  cursor: pointer;
}
.nav-toggle span {
  display: block;
  height: 2px;
  width: 22px;
  background: var(--text);
  margin: 0 auto;
  transition: transform 0.25s ease, opacity 0.25s ease;
}

.theme-toggle {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  flex-shrink: 0;
  transition: border-color 0.2s ease, transform 0.2s ease;
}
.theme-toggle:hover { border-color: var(--accent); transform: translateY(-1px); }
.theme-toggle svg { width: 18px; height: 18px; }
.theme-toggle .icon-moon { display: none; }
:root[data-theme="light"] .theme-toggle .icon-sun { display: none; }
:root[data-theme="light"] .theme-toggle .icon-moon { display: block; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 26px;
  border-radius: 100px;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform 0.2s ease, box-shadow 0.2s ease, opacity 0.2s ease, border-color 0.2s ease;
}
.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: var(--accent-contrast);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.btn-ghost {
  background: transparent;
  border-color: var(--border);
  color: var(--text);
}
.btn-ghost:hover { border-color: var(--accent); transform: translateY(-2px); }
.btn-block { width: 100%; }
.btn:disabled { opacity: 0.6; cursor: not-allowed; transform: none; }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: var(--header-h);
  overflow: hidden;
}
.hero-bg {
  position: absolute;
  inset: -20% -10%;
  background:
    radial-gradient(600px 400px at 15% 20%, color-mix(in srgb, var(--accent) 22%, transparent), transparent 60%),
    radial-gradient(700px 500px at 85% 60%, color-mix(in srgb, var(--accent-2) 20%, transparent), transparent 60%);
  z-index: -1;
  filter: blur(10px);
}
.hero-inner { padding: 90px 24px 60px; position: relative; z-index: 1; }

.cursor-glow {
  position: absolute;
  width: 480px;
  height: 480px;
  border-radius: 50%;
  background: radial-gradient(circle, color-mix(in srgb, var(--accent) 16%, transparent), transparent 70%);
  left: 0; top: 0;
  transform: translate(-50%, -50%);
  pointer-events: none;
  z-index: 0;
  opacity: 0;
  transition: opacity 0.4s ease;
  will-change: transform;
}
.cursor-glow.active { opacity: 1; }
@media (prefers-reduced-motion: reduce), (hover: none) {
  .cursor-glow { display: none; }
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent);
  margin: 0 0 18px;
}

.hero h1 {
  font-size: clamp(2.4rem, 6vw, 4rem);
  line-height: 1.08;
  letter-spacing: -0.03em;
  margin: 0 0 20px;
  font-weight: 800;
}
.highlight {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-sub {
  font-size: 1.15rem;
  color: var(--text-dim);
  max-width: 640px;
  margin: 0 0 36px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 64px;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, minmax(0,1fr));
  gap: 24px;
  max-width: 640px;
}
.stat { display: flex; flex-direction: column; }
.stat-num {
  font-size: 1.8rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text);
}
.stat-label {
  font-size: 0.82rem;
  color: var(--text-faint);
  margin-top: 2px;
}

.scroll-cue {
  position: absolute;
  bottom: 34px;
  left: 50%;
  transform: translateX(-50%);
  color: var(--text-faint);
  animation: bob 2.2s ease-in-out infinite;
}
@keyframes bob {
  0%, 100% { transform: translate(-50%, 0); }
  50% { transform: translate(-50%, 8px); }
}

/* ---------- Sections ---------- */
.section { padding: 110px 0; }
.section-alt { background: var(--bg-alt); }

.section-tag {
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent);
  margin: 0 0 14px;
}
.section-title {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  letter-spacing: -0.02em;
  margin: 0 0 20px;
  font-weight: 800;
  max-width: 720px;
}
.section-lead {
  color: var(--text-dim);
  max-width: 640px;
  font-size: 1.05rem;
  margin-bottom: 50px;
}

/* ---------- About ---------- */
.about-grid {
  display: grid;
  grid-template-columns: 1.3fr 0.9fr;
  gap: 60px;
  align-items: start;
  margin-top: 40px;
}
.about-text p { color: var(--text-dim); font-size: 1.02rem; }
.about-points {
  list-style: none;
  padding: 0;
  margin: 24px 0 0;
  display: grid;
  gap: 12px;
}
.about-points li {
  padding-left: 28px;
  position: relative;
  color: var(--text);
  font-size: 0.98rem;
}
.about-points li::before {
  content: "";
  position: absolute;
  left: 0; top: 8px;
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--accent);
}

.about-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px 30px;
  text-align: center;
}
.avatar-ring {
  width: 108px;
  height: 108px;
  border-radius: 50%;
  margin: 0 auto 20px;
  padding: 4px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
}
.avatar-photo {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  display: block;
}
.about-card h3 { margin: 0 0 4px; font-size: 1.25rem; }
.about-role { color: var(--accent); font-weight: 600; margin: 0 0 2px; font-size: 0.95rem; }
.about-company { color: var(--text-faint); margin: 0 0 22px; font-size: 0.9rem; }
.about-meta {
  list-style: none;
  padding: 0;
  margin: 0 0 26px;
  text-align: left;
  display: grid;
  gap: 10px;
  font-size: 0.88rem;
  color: var(--text-dim);
  border-top: 1px solid var(--border);
  padding-top: 20px;
}
.about-meta strong { color: var(--text); }

/* ---------- Timeline ---------- */
.timeline {
  position: relative;
  margin-top: 40px;
  padding-left: 28px;
  border-left: 2px solid var(--border);
  display: grid;
  gap: 48px;
}
.timeline-item { position: relative; }
.timeline-dot {
  position: absolute;
  left: -34px;
  top: 4px;
  width: 12px; height: 12px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--accent) 20%, transparent);
}
.timeline-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
}
.timeline-head h3 { margin: 0; font-size: 1.2rem; }
.timeline-date {
  font-size: 0.85rem;
  color: var(--text-faint);
  font-weight: 600;
  white-space: nowrap;
}
.timeline-org { color: var(--accent); font-weight: 600; margin: 4px 0 12px; font-size: 0.95rem; }
.timeline-desc { color: var(--text-dim); margin: 0 0 12px; }
.timeline-content ul { margin: 0 0 16px; padding-left: 20px; color: var(--text-dim); display: grid; gap: 6px; }
.timeline-content ul li { font-size: 0.95rem; }

/* Icon-only expand/collapse chevron, reused by .timeline-detail and .subproject */
.timeline-detail summary,
.subproject summary {
  cursor: pointer;
  list-style: none;
}
.timeline-detail summary::marker,
.subproject summary::marker { display: none; content: ""; }
.timeline-detail summary::-webkit-details-marker,
.subproject summary::-webkit-details-marker { display: none; }

.timeline-detail { margin-top: 10px; }
.timeline-detail summary {
  width: 22px;
  height: 22px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  transition: background 0.2s ease;
}
.timeline-detail summary:hover { background: var(--surface-2); }
.timeline-detail summary::before {
  content: "";
  width: 7px;
  height: 7px;
  border-right: 2px solid var(--accent);
  border-bottom: 2px solid var(--accent);
  transform: rotate(45deg);
  transition: transform 0.2s ease;
}
.timeline-detail:not([open]) summary::before { transform: rotate(-45deg); }
.timeline-detail[open] summary { margin-bottom: 10px; }

.timeline-subprojects { display: grid; gap: 12px; margin: 0 0 16px; }
.subproject {
  padding: 14px 18px;
  background: var(--surface-2);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
}
.subproject summary {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}
.subproject summary::after {
  content: "";
  width: 7px;
  height: 7px;
  border-right: 2px solid var(--accent);
  border-bottom: 2px solid var(--accent);
  transform: rotate(45deg);
  transition: transform 0.2s ease;
  flex-shrink: 0;
  margin-top: 6px;
}
.subproject[open] summary::after { transform: rotate(225deg); }
.subproject[open] summary { margin-bottom: 10px; }
.subproject h4 { margin: 0; font-size: 0.95rem; }
.subproject p { margin: 0; font-size: 0.9rem; color: var(--text-dim); }
.subproject p + ul { margin-top: 10px; }
.subproject ul { margin: 0; padding-left: 18px; color: var(--text-dim); display: grid; gap: 5px; }
.subproject ul li { font-size: 0.88rem; }
.subproject .tag-row { margin-top: 10px; }

.subproject-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 6px 14px;
  flex: 1;
}
.subproject-head h4 { margin: 0; }
.subproject-date {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-faint);
  white-space: nowrap;
}

.anon-note {
  color: var(--accent);
  cursor: help;
  font-weight: 700;
}
.anon-disclosure {
  margin-top: 36px;
  font-size: 0.82rem;
  color: var(--text-faint);
  font-style: italic;
}

.tag-row { display: flex; flex-wrap: wrap; gap: 8px; }
.tag {
  font-size: 0.78rem;
  font-weight: 600;
  padding: 6px 12px;
  border-radius: 100px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text-dim);
}

/* ---------- Skills ---------- */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0,1fr));
  gap: 24px;
  margin-top: 40px;
}
.skill-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 26px;
}
.skill-card h3 { margin: 0 0 16px; font-size: 1.05rem; }

/* ---------- Projects ---------- */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0,1fr));
  gap: 24px;
  margin-top: 10px;
}
.project-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 28px;
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.project-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent);
  box-shadow: var(--shadow);
}
.project-tag {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 14%, transparent);
  padding: 5px 12px;
  border-radius: 100px;
  margin-bottom: 14px;
}
.project-card h3 { margin: 0 0 10px; font-size: 1.15rem; }
.project-card p { color: var(--text-dim); font-size: 0.95rem; margin: 0 0 16px; }
.project-card-placeholder { border-style: dashed; opacity: 0.85; }

/* ---------- Certifications ---------- */
.cred-columns {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  margin-top: 40px;
}
.cred-heading { font-size: 1.1rem; margin: 0 0 20px; }
.cred-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
}
.cred-list li {
  padding: 14px 18px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.93rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}
.patent-status {
  font-size: 0.72rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 100px;
  white-space: nowrap;
  flex-shrink: 0;
}
.status-approved { background: color-mix(in srgb, var(--success) 20%, transparent); color: var(--success); }
.status-review { background: color-mix(in srgb, var(--accent-2) 20%, transparent); color: var(--accent-2); }

/* Patents (full width, below the certifications/education columns) */
.patents-full { margin-top: 50px; }
.patent-cards { display: grid; gap: 20px; }
.patent-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 26px;
  transition: border-color 0.25s ease;
}
.patent-card:hover { border-color: var(--accent); }
.patent-card-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 10px;
}
.patent-card-head h4 { margin: 0; font-size: 1.1rem; line-height: 1.35; }
.patent-desc { color: var(--text-dim); font-size: 0.92rem; margin: 0 0 14px; max-width: 760px; }

.patent-meta {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 8px 16px;
  margin: 0 0 14px;
  padding: 12px 14px;
  background: var(--surface-2);
  border-radius: var(--radius-sm);
  max-width: 760px;
}
.patent-meta div { display: flex; flex-direction: column; }
.patent-meta dt { font-size: 0.7rem; text-transform: uppercase; letter-spacing: 0.04em; color: var(--text-faint); }
.patent-meta dd { margin: 0; font-size: 0.85rem; font-weight: 600; color: var(--text); }

.patent-inventors {
  font-size: 0.85rem;
  color: var(--text-dim);
  margin: 0 0 16px;
  line-height: 1.6;
  max-width: 760px;
}
.patent-inventors .me { color: var(--accent); }

.patent-links { display: flex; flex-wrap: wrap; gap: 10px 20px; }
.patent-links a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
  transition: color 0.2s ease;
}
.patent-links a:hover { color: var(--accent); }
.patent-links a svg { color: var(--text-faint); transition: color 0.2s ease; flex-shrink: 0; }
.patent-links a:hover svg { color: var(--accent); }

/* Expandable "how it works" detail */
.patent-detail {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
}
.patent-detail summary {
  cursor: pointer;
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--accent);
  list-style: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.patent-detail summary::-webkit-details-marker { display: none; }
.patent-detail summary::before {
  content: "";
  width: 8px;
  height: 8px;
  border-right: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
  transform: rotate(-45deg);
  transition: transform 0.2s ease;
  flex-shrink: 0;
}
.patent-detail[open] summary::before { transform: rotate(45deg); }

.patent-figure {
  margin: 18px 0;
  padding: 18px;
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}
.patent-figure img { width: 100%; height: auto; display: block; }
.patent-figure figcaption {
  margin-top: 10px;
  font-size: 0.78rem;
  color: var(--text-faint);
  text-align: center;
  font-style: italic;
}

.patent-steps {
  margin: 0;
  padding-left: 22px;
  display: grid;
  gap: 10px;
  max-width: 760px;
}
.patent-steps li { color: var(--text-dim); font-size: 0.92rem; }

@media (max-width: 700px) {
  .patent-meta { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 500px) {
  .patent-meta { grid-template-columns: 1fr; }
}

/* ---------- Contact ---------- */
.contact-grid {
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  gap: 40px;
  margin-top: 10px;
}
.contact-panel { display: grid; gap: 14px; align-content: start; }
.contact-option {
  display: flex;
  align-items: center;
  gap: 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 18px 20px;
  transition: border-color 0.2s ease, transform 0.2s ease;
  font-size: 0.92rem;
}
.contact-option:hover { border-color: var(--accent); transform: translateY(-2px); }
.contact-option strong { display: block; font-size: 0.95rem; margin-bottom: 2px; }
.contact-icon {
  width: 40px; height: 40px;
  border-radius: 50%;
  background: var(--surface-2);
  display: flex; align-items: center; justify-content: center;
  color: var(--accent);
  flex-shrink: 0;
}

.contact-form {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 34px;
  display: grid;
  gap: 18px;
}
.hp-field { position: absolute; left: -9999px; opacity: 0; height: 0; width: 0; }
.form-row { display: grid; gap: 8px; }
.form-row label { font-size: 0.85rem; font-weight: 600; color: var(--text-dim); }
.form-row input, .form-row textarea {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  color: var(--text);
  font-family: inherit;
  font-size: 0.95rem;
  resize: vertical;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.form-row input:focus, .form-row textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 18%, transparent);
}
.form-row input.invalid, .form-row textarea.invalid {
  border-color: var(--danger);
  animation: shake 0.35s ease;
}
.form-row input.valid, .form-row textarea.valid {
  border-color: var(--success);
}
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-5px); }
  75% { transform: translateX(5px); }
}
.field-error {
  font-size: 0.8rem;
  color: var(--danger);
  min-height: 1.1em;
  display: block;
}
.form-status {
  font-size: 0.88rem;
  min-height: 1.2em;
  margin: 0;
}
.form-status.success { color: var(--success); }
.form-status.error { color: var(--danger); }

.btn-spinner {
  display: none;
  width: 16px; height: 16px;
  border-radius: 50%;
  border: 2px solid color-mix(in srgb, var(--accent-contrast) 40%, transparent);
  border-top-color: var(--accent-contrast);
  animation: spin 0.7s linear infinite;
}
.btn.is-loading .btn-spinner { display: inline-block; }
.btn.is-loading .btn-label { opacity: 0.85; }
@keyframes spin { to { transform: rotate(360deg); } }

/* Email copy button */
.contact-option-email { display: flex; align-items: stretch; gap: 0; padding: 0; overflow: hidden; }
.contact-option-link {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 18px 20px;
  flex: 1;
  font-size: 0.92rem;
  min-width: 0;
}
.copy-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 52px;
  border: none;
  border-left: 1px solid var(--border);
  background: var(--surface-2);
  color: var(--text-dim);
  cursor: pointer;
  transition: color 0.2s ease, background 0.2s ease;
  flex-shrink: 0;
}
.copy-btn:hover { color: var(--accent); background: color-mix(in srgb, var(--accent) 10%, transparent); }
.copy-btn.copied { color: var(--success); }

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
  background: var(--bg-alt);
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
  color: var(--text-faint);
  font-size: 0.88rem;
}
.footer-links { display: flex; gap: 22px; }
.footer-links a:hover { color: var(--accent); }

/* ---------- Reveal animation ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}
.reveal.in-view { opacity: 1; transform: translateY(0); }

/* Staggered reveal for grids */
.hero-stats .stat:nth-child(1) { transition-delay: 0ms; }
.hero-stats .stat:nth-child(2) { transition-delay: 80ms; }
.hero-stats .stat:nth-child(3) { transition-delay: 160ms; }
.hero-stats .stat:nth-child(4) { transition-delay: 240ms; }

.skills-grid .skill-card:nth-child(1) { transition-delay: 0ms; }
.skills-grid .skill-card:nth-child(2) { transition-delay: 90ms; }
.skills-grid .skill-card:nth-child(3) { transition-delay: 180ms; }
.skills-grid .skill-card:nth-child(4) { transition-delay: 270ms; }

.projects-grid .project-card:nth-child(1) { transition-delay: 0ms; }
.projects-grid .project-card:nth-child(2) { transition-delay: 90ms; }
.projects-grid .project-card:nth-child(3) { transition-delay: 180ms; }
.projects-grid .project-card:nth-child(4) { transition-delay: 270ms; }

/* ---------- Back to top ---------- */
.back-to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: var(--shadow);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity 0.25s ease, transform 0.25s ease, border-color 0.2s ease, visibility 0.25s;
  z-index: 500;
}
.back-to-top.visible { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover { border-color: var(--accent); color: var(--accent); transform: translateY(-3px); }

/* ---------- WhatsApp floating button ---------- */
.whatsapp-float {
  position: fixed;
  left: 24px;
  bottom: 24px;
  width: 54px;
  height: 54px;
  border-radius: 50%;
  background: #25d366;
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 12px 30px -10px rgba(37, 211, 102, 0.6);
  z-index: 500;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.whatsapp-float:hover { transform: translateY(-3px) scale(1.04); box-shadow: 0 16px 36px -8px rgba(37, 211, 102, 0.7); }
.whatsapp-float[hidden] { display: none; }

.contact-icon-whatsapp { color: #25d366; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
  .scroll-cue { animation: none; }
  .btn-spinner { animation: none; }
}

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .about-grid, .contact-grid, .cred-columns { grid-template-columns: 1fr; }
  .skills-grid, .projects-grid { grid-template-columns: 1fr; }
  .hero-stats { grid-template-columns: repeat(2, minmax(0,1fr)); }
}

@media (max-width: 760px) {
  .nav-toggle { display: flex; }
  .nav-links {
    position: fixed;
    top: var(--header-h);
    left: 0; right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    align-items: flex-start;
    padding: 24px;
    gap: 18px;
    transform: translateY(-130%);
    transition: transform 0.3s ease;
  }
  .nav-links.open { transform: translateY(0); }
  .nav-links a.nav-cta { align-self: flex-start; }
  .section { padding: 80px 0; }
}