/* ===== Custom properties ===== */
:root {
  --color-bg: #dde2e4;
  --color-bg-alt: #d2d9db;
  --color-surface: #e6eaeb;
  --color-surface-raised: #eaeeee;
  --color-border: #b9c2c5;
  --color-text: #0f172a;
  --color-text-muted: #475569;
  --color-text-dim: #64748b;
  --color-accent: #0f766e;
  --color-accent-bright: #115e59;
  --color-accent-dim: #99f6e4;
  --color-accent-soft: rgba(15, 118, 110, 0.08);
  --color-link: #0f766e;

  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;

  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2.5rem;
  --space-xl: 4rem;
  --space-xxl: 6rem;

  --radius: 8px;
  --max-width: 1120px;

  --transition-fast: 0.18s ease;
  --transition-med: 0.35s cubic-bezier(0.22, 1, 0.36, 1);

  --shadow-card: 0 4px 20px rgba(15, 23, 42, 0.08);
  --shadow-glow: 0 0 28px rgba(15, 118, 110, 0.18);
}

/* ===== Reset ===== */
* , *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

h1, h2, h3, h4 {
  font-family: var(--font-body);
  font-weight: 700;
  line-height: 1.2;
  margin: 0 0 var(--space-sm);
  letter-spacing: -0.01em;
}

h1 { font-size: clamp(2.2rem, 5vw, 3.4rem); }
h2 { font-size: clamp(1.6rem, 3.5vw, 2.2rem); }
h3 { font-size: 1.25rem; }

p { margin: 0 0 var(--space-sm); color: var(--color-text-muted); }

a {
  color: var(--color-link);
  text-decoration: none;
  transition: color var(--transition-fast);
}
a:hover, a:focus-visible { color: var(--color-accent-bright); }

.mono { font-family: var(--font-mono); }

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

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

/* Skip link */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--color-accent);
  color: #ffffff;
  padding: 0.6rem 1rem;
  z-index: 1000;
  border-radius: 0 0 6px 0;
  font-weight: 600;
}
.skip-link:focus {
  left: 0;
}

/* ===== Background grid texture ===== */
body {
  background-image:
    linear-gradient(rgba(15, 118, 110, 0.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(15, 118, 110, 0.055) 1px, transparent 1px);
  background-size: 48px 48px;
  background-position: center top;
}

/* ===== Header / Nav ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(247, 249, 251, 0.82);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-sm) var(--space-md);
  max-width: var(--max-width);
  margin: 0 auto;
}

.nav-brand {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.nav-brand:hover { color: var(--color-text); }
.nav-brand .bracket { color: var(--color-accent); }

.nav-links {
  display: flex;
  gap: var(--space-lg);
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  font-weight: 500;
  position: relative;
  padding: 0.25rem 0;
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 0; bottom: -2px;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  transition: width var(--transition-fast);
}
.nav-links a:hover::after,
.nav-links a[aria-current="page"]::after {
  width: 100%;
}
.nav-links a[aria-current="page"] {
  color: var(--color-text);
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  color: var(--color-text);
  padding: 0.4rem 0.6rem;
  cursor: pointer;
}

.nav-toggle svg { width: 22px; height: 22px; display: block; }

@media (max-width: 720px) {
  .nav-toggle { display: block; }
  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    background: var(--color-bg-alt);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-sm) var(--space-md) var(--space-md);
    gap: var(--space-sm);
    display: none;
  }
  .nav-links.is-open { display: flex; }
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.85rem 1.6rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), background var(--transition-fast), border-color var(--transition-fast);
  min-height: 44px;
}

.btn-primary {
  background: var(--color-accent);
  color: #ffffff;
}
.btn-primary:hover {
  background: var(--color-accent-bright);
  color: #ffffff;
  box-shadow: var(--shadow-glow);
  transform: translateY(-1px);
}

.btn-secondary {
  background: transparent;
  border-color: var(--color-border);
  color: var(--color-text);
}
.btn-secondary:hover {
  border-color: var(--color-accent);
  color: var(--color-accent-bright);
  transform: translateY(-1px);
}

.btn-row {
  display: flex;
  gap: var(--space-sm);
  flex-wrap: wrap;
  margin-top: var(--space-md);
}

/* ===== Hero ===== */
.hero {
  padding: clamp(3.5rem, 10vw, 7rem) 0 var(--space-xl);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -20%;
  right: -10%;
  width: 60vw;
  height: 60vw;
  max-width: 700px;
  max-height: 700px;
  background: radial-gradient(circle, rgba(15, 118, 110, 0.12) 0%, transparent 70%);
  pointer-events: none;
}

.hero-eyebrow {
  font-family: var(--font-mono);
  color: var(--color-accent);
  font-size: 0.9rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: var(--space-sm);
  display: inline-block;
}

.hero-lead {
  max-width: 620px;
  font-size: 1.15rem;
}

/* ===== Hero simulation graphic ===== */
.hero-sim {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  width: 52%;
  pointer-events: none;
  opacity: 0.5;
  z-index: 0;
  mask-image: linear-gradient(to left, black 40%, transparent 95%);
  -webkit-mask-image: linear-gradient(to left, black 40%, transparent 95%);
}

.hero-waveform {
  width: 100%;
  height: 100%;
}

.waveform-grid {
  fill: none;
  stroke: var(--color-border);
  stroke-width: 1;
}

.waveform-path {
  fill: none;
  stroke: var(--color-accent);
  stroke-width: 2;
  stroke-linecap: round;
  filter: drop-shadow(0 0 5px rgba(15, 118, 110, 0.35));
  stroke-dasharray: 1800;
  stroke-dashoffset: 1800;
  animation: draw-waveform 7s ease-in-out infinite alternate;
}

@keyframes draw-waveform {
  0% { stroke-dashoffset: 1800; }
  100% { stroke-dashoffset: 0; }
}

@media (max-width: 720px) {
  .hero-sim { display: none; }
}

.hero > .container {
  position: relative;
  z-index: 1;
}

.hero-telemetry {
  color: var(--color-text-dim);
  font-size: 0.85rem;
  letter-spacing: 0.02em;
  margin: -0.4rem 0 var(--space-md);
}

.hero-telemetry .cursor {
  color: var(--color-accent);
  margin-left: 0.2rem;
  animation: cursor-blink 1s step-end infinite;
}

@keyframes cursor-blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0; }
}

@media (prefers-reduced-motion: reduce) {
  .waveform-path {
    animation: none;
    stroke-dashoffset: 0;
  }
  .hero-telemetry .cursor {
    animation: none;
  }
}

/* ===== Sections ===== */
.section {
  padding: var(--space-xxl) 0;
  border-top: 1px solid var(--color-border);
}
.section-alt { background: var(--color-bg-alt); }

.section-head {
  max-width: 640px;
  margin-bottom: var(--space-lg);
}

.section-eyebrow {
  font-family: var(--font-mono);
  color: var(--color-accent);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

/* ===== Cards / grid ===== */
.grid {
  display: grid;
  gap: var(--space-md);
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-md);
  transition: transform var(--transition-med), border-color var(--transition-fast), box-shadow var(--transition-med);
}
.card:hover {
  transform: translateY(-4px);
  border-color: var(--color-accent-dim);
  box-shadow: var(--shadow-card);
}

.card-icon {
  width: 42px;
  height: 42px;
  border-radius: 6px;
  background: var(--color-accent-soft);
  color: var(--color-accent);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-sm);
}
.card-icon svg { width: 22px; height: 22px; }

/* ===== Education list (About page) ===== */
.edu-list {
  list-style: none;
  margin: var(--space-sm) 0 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.edu-list li {
  position: relative;
  padding-left: 1.2rem;
  color: var(--color-text-muted);
}

.edu-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.55em;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-accent);
}

/* ===== Timeline (About page) ===== */
.timeline {
  border-left: 2px solid var(--color-border);
  margin-left: 6px;
  padding-left: var(--space-lg);
}

.timeline-item {
  position: relative;
  padding-bottom: var(--space-lg);
}
.timeline-item:last-child { padding-bottom: 0; }

.timeline-item::before {
  content: "";
  position: absolute;
  left: calc(-1 * var(--space-lg) - 7px);
  top: 4px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-bg);
  border: 2px solid var(--color-accent);
}

.timeline-meta {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin: 0 0 0.4rem;
}

.timeline-year {
  font-family: var(--font-mono);
  color: var(--color-accent);
  font-weight: 700;
  font-size: 0.95rem;
}

.timeline-role {
  margin: 0;
  font-family: var(--font-mono);
  font-weight: 400;
  font-size: 0.9rem;
  color: var(--color-text-muted);
  padding-left: 0.6rem;
  border-left: 1px solid var(--color-border);
}

/* ===== Skills ===== */
.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  list-style: none;
  padding: 0;
  margin: 0;
}

.tag {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  padding: 0.4rem 0.8rem;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  color: var(--color-text-muted);
  background: var(--color-surface);
}

/* ===== Forms ===== */
.form-field {
  margin-bottom: var(--space-md);
}

.form-field label {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 0.4rem;
  color: var(--color-text);
}

.form-field input,
.form-field textarea {
  width: 100%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  color: var(--color-text);
  padding: 0.8rem 1rem;
  font-family: var(--font-body);
  font-size: 1rem;
  transition: border-color var(--transition-fast);
}

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

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

.form-hint {
  font-size: 0.8rem;
  color: var(--color-text-dim);
  margin-top: 0.3rem;
}

.form-error {
  font-size: 0.85rem;
  color: #b91c1c;
  margin-top: 0.3rem;
  display: none;
}
.form-field.has-error input,
.form-field.has-error textarea {
  border-color: #dc2626;
}
.form-field.has-error .form-error { display: block; }

.form-status {
  padding: 0.9rem 1rem;
  border-radius: var(--radius);
  margin-bottom: var(--space-md);
  font-size: 0.95rem;
  display: none;
}
.form-status.is-visible { display: block; }
.form-status.is-success {
  background: var(--color-accent-bright);
  border: 1px solid var(--color-accent-bright);
  color: #ffffff;
}
.form-status.is-error {
  background: rgba(220, 38, 38, 0.08);
  border: 1px solid rgba(220, 38, 38, 0.35);
  color: #b91c1c;
}

.contact-form-wrap {
  max-width: 640px;
}

/* ===== Footer ===== */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding: var(--space-lg) 0;
  background: var(--color-bg-alt);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.footer-links {
  display: flex;
  gap: var(--space-md);
  list-style: none;
  padding: 0;
  margin: 0;
}

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

.footer-copy {
  color: var(--color-text-dim);
  font-size: 0.85rem;
  font-family: var(--font-mono);
}

/* ===== Scroll reveal ===== */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s cubic-bezier(0.22, 1, 0.36, 1);
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
  * {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
  }
}

/* ===== Utility spacing ===== */
.mt-lg { margin-top: var(--space-lg); }