/* =====================================================================
   Samantha An — Portfolio stylesheet
   Plain CSS, no frameworks. Layout mirrors the "Senior Software Engineer
   Portfolio" reference but is written from scratch.
   ===================================================================== */

/* ---------- Design tokens (light) ---------- */
:root {
  --font-size: 14px;
  --font-sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;

  --background: #ffffff;
  --foreground: #252525;
  --card: #ffffff;
  --card-foreground: #252525;
  --primary: #030213;
  --primary-foreground: #ffffff;
  --primary-rgb: 3, 2, 19;
  --secondary: #eff0f4;
  --secondary-foreground: #030213;
  --muted: #ececf0;
  --muted-foreground: #717182;
  --accent: #e9ebef;
  --accent-foreground: #030213;
  --border: rgba(0, 0, 0, 0.1);
  --input-background: #f3f3f5;
  --ring: #b5b5b5;
  --success: #22c55e;

  --radius: 0.625rem;
  --radius-sm: calc(var(--radius) - 4px);
  --radius-md: calc(var(--radius) - 2px);
  --radius-lg: var(--radius);
  --radius-xl: calc(var(--radius) + 4px);

  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
  --shadow-2xl: 0 25px 50px -12px rgb(0 0 0 / 0.25);

  --nav-height: 4rem;
  color-scheme: light;
}

/* ---------- Design tokens (dark) ---------- */
.dark {
  --background: #252525;
  --foreground: #fbfbfb;
  --card: #252525;
  --card-foreground: #fbfbfb;
  --primary: #fbfbfb;
  --primary-foreground: #343434;
  --primary-rgb: 251, 251, 251;
  --secondary: #444444;
  --secondary-foreground: #fbfbfb;
  --muted: #444444;
  --muted-foreground: #b5b5b5;
  --accent: #444444;
  --accent-foreground: #fbfbfb;
  --border: #444444;
  --input-background: #444444;
  --ring: #707070;
  color-scheme: dark;
}

/* ---------- Reset & base ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  border-color: var(--border);
}

html {
  font-size: var(--font-size);
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  margin: 0;
  font-family: var(--font-sans);
  line-height: 1.5;
  background: var(--background);
  color: var(--foreground);
  transition: background-color 0.3s ease, color 0.3s ease;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, p {
  margin: 0;
}

h1, h2, h3, h4 {
  font-weight: 500;
  line-height: 1.5;
}

h2 { font-size: 1.875rem; letter-spacing: -0.01em; }
h3 { font-size: 1.125rem; }
h4 { font-size: 1rem; }

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

svg.icon {
  width: 1.25rem;
  height: 1.25rem;
  flex-shrink: 0;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

svg.icon--sm {
  width: 1rem;
  height: 1rem;
}

/* ---------- Utilities ---------- */
.container {
  width: 100%;
  max-width: 80rem;
  margin: 0 auto;
  padding: 0 1rem;
}
.container--md { max-width: 72rem; }
.container--sm { max-width: 56rem; }

.text-primary { color: var(--primary); }
.text-muted { color: var(--muted-foreground); }

.stack > * + * { margin-top: 1.5rem; }

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.grid {
  display: grid;
  gap: 1.5rem;
  grid-template-columns: 1fr;
}
.grid--wide { gap: 2rem; }

.dot {
  width: 0.75rem;
  height: 0.75rem;
  border-radius: 999px;
  background: var(--success);
  display: inline-block;
}
.dot--pulse { animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  height: 2.25rem;
  padding: 0 1rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  font: inherit;
  font-weight: 500;
  font-size: 0.875rem;
  white-space: nowrap;
  cursor: pointer;
  background: transparent;
  color: inherit;
  transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease, opacity 0.2s ease;
}
.btn:focus-visible {
  outline: 2px solid var(--ring);
  outline-offset: 2px;
}

.btn--primary {
  background: var(--primary);
  color: var(--primary-foreground);
}
.btn--primary:hover { opacity: 0.9; }

.btn--outline {
  border-color: var(--border);
  background: var(--background);
}
.btn--outline:hover {
  background: var(--accent);
  color: var(--accent-foreground);
}

.btn--ghost:hover {
  background: var(--accent);
  color: var(--accent-foreground);
}

.btn--lg {
  height: 3.5rem;
  padding: 0 2rem;
  font-size: 1rem;
}
.btn--sm {
  height: 2rem;
  padding: 0 0.75rem;
  font-size: 0.8125rem;
}
.btn--icon {
  width: 2.25rem;
  height: 2.25rem;
  padding: 0;
}
.btn--round {
  width: 3rem;
  height: 3rem;
  border-radius: 999px;
  border: 1px solid rgba(var(--primary-rgb), 0.1);
  background: rgba(255, 255, 255, 0.5);
  backdrop-filter: blur(4px);
}
.dark .btn--round { background: rgba(37, 37, 37, 0.5); }
.btn--round:hover {
  background: rgba(var(--primary-rgb), 0.1);
  border-color: rgba(var(--primary-rgb), 0.3);
}
.btn--block { width: 100%; }

/* ---------- Badges ---------- */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.125rem 0.5rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  font-size: 0.75rem;
  font-weight: 500;
  line-height: 1.5;
  white-space: nowrap;
}
.badge--secondary {
  background: var(--secondary);
  color: var(--secondary-foreground);
}
.badge--outline {
  border-color: var(--border);
  color: var(--foreground);
}
.badge--primary {
  padding: 0.75rem 1.5rem;
  gap: 0.5rem;
  border-radius: 999px;
  font-size: 0.875rem;
  background: rgba(var(--primary-rgb), 0.1);
  color: var(--primary);
  border-color: rgba(var(--primary-rgb), 0.2);
  backdrop-filter: blur(4px);
}

/* ---------- Cards ---------- */
.card {
  display: flex;
  flex-direction: column;
  background: var(--card);
  color: var(--card-foreground);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  overflow: hidden;
  transition: background-color 0.3s ease, border-color 0.3s ease;
}
.card--link:hover { border-color: rgba(var(--primary-rgb), 0.3); }

.card__header {
  padding: 1.5rem 1.5rem 0;
}
.card__title {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1rem;
  font-weight: 500;
}
.card__content {
  padding: 1.5rem;
}
.card__content > * + * { margin-top: 1rem; }
.card__content--row {
  display: flex;
  align-items: center;
  gap: 1rem;
}
.card__content--row > * + * { margin-top: 0; }

/* ---------- Forms ---------- */
.input {
  display: block;
  width: 100%;
  min-height: 2.25rem;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  background: var(--input-background);
  color: var(--foreground);
  font: inherit;
  font-size: 0.875rem;
  resize: vertical;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.input::placeholder { color: var(--muted-foreground); }
.input:focus {
  outline: none;
  border-color: var(--ring);
  box-shadow: 0 0 0 3px rgba(var(--primary-rgb), 0.1);
}
.form-row {
  display: grid;
  gap: 1rem;
  grid-template-columns: 1fr;
}

/* ---------- Navigation ---------- */
.nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 50;
  background: color-mix(in srgb, var(--background) 95%, transparent);
  backdrop-filter: blur(4px);
  border-bottom: 1px solid var(--border);
}
.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--nav-height);
}
.nav__brand {
  font-size: 1.125rem;
  font-weight: 500;
  letter-spacing: -0.01em;
}
.nav__links {
  display: none;
  align-items: baseline;
  gap: 1rem;
}
.nav__links a {
  padding: 0.5rem 0.75rem;
  font-size: 0.875rem;
  color: var(--muted-foreground);
  transition: color 0.2s ease;
}
.nav__links a:hover { color: var(--foreground); }
.nav__actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.nav__mobile {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 0.5rem 0.5rem 0.75rem;
  background: var(--background);
  border-top: 1px solid var(--border);
}
.nav__mobile a {
  display: block;
  padding: 0.5rem 0.75rem;
  color: var(--muted-foreground);
  font-size: 1rem;
}
.nav__mobile a:hover { color: var(--foreground); }
.nav__mobile[hidden] { display: none; }

/* Theme + menu icon swaps */
.theme-toggle { position: relative; }
.theme-toggle .icon {
  width: 1rem;
  height: 1rem;
  transition: transform 0.3s ease, opacity 0.3s ease;
}
.theme-toggle .icon--moon {
  position: absolute;
  transform: rotate(90deg) scale(0);
  opacity: 0;
}
.dark .theme-toggle .icon--sun {
  transform: rotate(-90deg) scale(0);
  opacity: 0;
}
.dark .theme-toggle .icon--moon {
  transform: rotate(0) scale(1);
  opacity: 1;
}
.nav__menu-btn .icon { width: 1.5rem; height: 1.5rem; }
.nav__menu-btn .icon--close { display: none; }
.nav__menu-btn[aria-expanded="true"] .icon--menu { display: none; }
.nav__menu-btn[aria-expanded="true"] .icon--close { display: block; }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding: calc(var(--nav-height) + 3rem) 0 5rem;
}
.hero__bg {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, var(--background) 0%, var(--background) 60%, rgba(var(--primary-rgb), 0.05) 100%);
}
.hero__blob {
  position: absolute;
  border-radius: 999px;
  filter: blur(64px);
  animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}
.hero__blob--1 { top: 5rem; left: 2.5rem; width: 8rem; height: 8rem; background: rgba(var(--primary-rgb), 0.05); }
.hero__blob--2 { top: 10rem; right: 5rem; width: 12rem; height: 12rem; background: color-mix(in srgb, var(--secondary) 30%, transparent); animation-delay: 0.7s; }
.hero__blob--3 { bottom: 10rem; left: 5rem; width: 10rem; height: 10rem; background: color-mix(in srgb, var(--accent) 20%, transparent); animation-delay: 1s; }
.hero__grid {
  position: absolute;
  inset: 0;
  opacity: 0.05;
  background-image: linear-gradient(to right, color-mix(in srgb, var(--foreground) 10%, transparent) 1px, transparent 1px);
  background-size: calc(100% / 12) 100%;
}

.hero__inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 3rem;
  align-items: center;
  grid-template-columns: 1fr;
}
.hero__content {
  order: 2;
  text-align: center;
}
.hero__content > * + * { margin-top: 2rem; }
.hero__badge-row {
  display: flex;
  justify-content: center;
}
.hero__title {
  font-size: 2.25rem;
  line-height: 1.1;
  letter-spacing: -0.02em;
  font-weight: 500;
}
.hero__title span { display: block; }
.hero__name {
  background: linear-gradient(to right, var(--primary), var(--primary) 60%, rgba(var(--primary-rgb), 0.7));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero__tagline {
  margin-top: 1.5rem;
  font-size: 1.25rem;
  color: var(--muted-foreground);
  max-width: 32rem;
  margin-left: auto;
  margin-right: auto;
}
.hero__sub {
  margin-top: 1rem;
  font-size: 1.125rem;
  color: color-mix(in srgb, var(--muted-foreground) 80%, transparent);
  max-width: 28rem;
  margin-left: auto;
  margin-right: auto;
}
.hero__cta {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  justify-content: center;
}
.hero__cta .btn--outline {
  background: color-mix(in srgb, var(--background) 50%, transparent);
  border-color: rgba(var(--primary-rgb), 0.2);
  backdrop-filter: blur(4px);
}
.hero__cta .btn--outline:hover { background: rgba(var(--primary-rgb), 0.1); }
.hero__social {
  display: flex;
  gap: 1rem;
  justify-content: center;
}
.hero__stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  padding-top: 2rem;
}
.stat { text-align: center; }
.stat__value {
  font-size: 1.5rem;
  margin-bottom: 0.25rem;
}
.stat__label {
  font-size: 0.875rem;
  color: var(--muted-foreground);
}

.hero__visual {
  order: 1;
  position: relative;
  display: flex;
  justify-content: center;
}
.hero__glow {
  position: absolute;
  border-radius: 999px;
  filter: blur(64px);
  pointer-events: none;
}
.hero__glow--1 {
  top: -1rem; left: calc(50% - 10rem);
  width: 18rem; height: 18rem;
  background: linear-gradient(135deg, rgba(var(--primary-rgb), 0.2), color-mix(in srgb, var(--secondary) 20%, transparent));
  opacity: 0.6;
}
.hero__glow--2 {
  bottom: -1rem; right: calc(50% - 10rem);
  width: 16rem; height: 16rem;
  background: linear-gradient(315deg, color-mix(in srgb, var(--accent) 30%, transparent), rgba(var(--primary-rgb), 0.1));
  opacity: 0.4;
}
.hero__portrait-wrap {
  position: relative;
  z-index: 1;
}
.hero__portrait {
  width: 20rem;
  height: 20rem;
  border-radius: 999px;
  overflow: hidden;
  border: 4px solid color-mix(in srgb, var(--background) 50%, transparent);
  box-shadow: var(--shadow-2xl);
  background: linear-gradient(135deg, rgba(var(--primary-rgb), 0.1), color-mix(in srgb, var(--secondary) 10%, transparent));
  position: relative;
}
.hero__portrait img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  transition: transform 0.5s ease;
}
.hero__portrait-wrap:hover .hero__portrait img { transform: scale(1.05); }
.hero__portrait::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(to top, rgba(var(--primary-rgb), 0.2), transparent 50%);
  pointer-events: none;
}
.hero__initials {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 5rem;
  font-weight: 500;
  letter-spacing: -0.04em;
  color: var(--primary);
  background: linear-gradient(135deg, var(--secondary), var(--muted));
}
.hero__float-badge {
  position: absolute;
  bottom: -1.5rem;
  right: -1.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 1.5rem;
  border-radius: 1rem;
  font-size: 0.875rem;
  background: color-mix(in srgb, var(--background) 90%, transparent);
  border: 1px solid rgba(var(--primary-rgb), 0.2);
  backdrop-filter: blur(4px);
  box-shadow: var(--shadow-xl);
}

.hero__scroll {
  position: absolute;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  display: none;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: var(--muted-foreground);
  animation: bounce 1s infinite;
}

/* ---------- Sections ---------- */
.section {
  padding: 5rem 0;
}
.section--tinted {
  background: color-mix(in srgb, var(--secondary) 5%, transparent);
}
.section__head {
  text-align: center;
  margin-bottom: 3rem;
}
.section__head p {
  margin: 1rem auto 0;
  max-width: 42rem;
  color: var(--muted-foreground);
}

/* Experience */
.exp__top {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.exp__company { margin-top: 0.25rem; }
.exp__meta {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  color: var(--muted-foreground);
}
.exp__meta span {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Projects */
.project__thumb {
  aspect-ratio: 16 / 9;
  width: 100%;
  overflow: hidden;
  background-size: cover;
  transition: transform 0.3s ease;
  display: flex;
  align-items: center;
  justify-content: center;
}
.project__thumb img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
}
.project__thumb--cover img { object-fit: cover; }
.card--project:hover .project__thumb { transform: scale(1.03); }
.project__thumb--a { background: linear-gradient(135deg, #ceced3, #dcdcdc); }
.card--project .card__content {
  flex: 1;
  display: flex;
  flex-direction: column;
}
.project__links {
  display: flex;
  gap: 0.5rem;
  padding-top: 0.5rem;
}
.card--project .project__links { margin-top: auto; padding-top: 1.5rem; }

/* Contact */
.contact {
  display: grid;
  gap: 3rem;
  grid-template-columns: 1fr;
  align-items: start;
}
.contact__form { margin: 0; }

/* ---------- Footer ---------- */
.footer {
  padding: 3rem 0;
  text-align: center;
  background: color-mix(in srgb, var(--secondary) 10%, transparent);
}
.footer h3 { margin-bottom: 1rem; }
.footer__copy {
  margin-top: 1.5rem;
  font-size: 0.875rem;
}

/* ---------- Animations ---------- */
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}
@keyframes bounce {
  0%, 100% { transform: translate(-50%, -25%); animation-timing-function: cubic-bezier(0.8, 0, 1, 1); }
  50% { transform: translate(-50%, 0); animation-timing-function: cubic-bezier(0, 0, 0.2, 1); }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
  html { scroll-behavior: auto; }
}

/* ---------- Responsive ---------- */
@media (min-width: 640px) {
  .container { padding: 0 1.5rem; }
  .hero__title { font-size: 3rem; }
  .hero__tagline { font-size: 1.5rem; }
  .hero__cta { flex-direction: row; }
  .form-row { grid-template-columns: 1fr 1fr; }
  .hero__scroll { display: flex; }
}

@media (min-width: 768px) {
  h2 { font-size: 2.25rem; }
  .nav__links { display: flex; }
  .nav__menu-btn { display: none; }
  .nav__mobile { display: none !important; }
  .grid--3 { grid-template-columns: repeat(2, 1fr); }
  .stat__value { font-size: 1.875rem; }
  .exp__top {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
  .exp__meta { align-items: flex-end; }
}

@media (min-width: 1024px) {
  .container { padding: 0 2rem; }
  .hero__title { font-size: 3.75rem; }
  .hero__inner {
    grid-template-columns: 1fr 1fr;
    gap: 5rem;
  }
  .hero__content { order: 1; text-align: left; }
  .hero__visual { order: 2; }
  .hero__badge-row,
  .hero__cta,
  .hero__social { justify-content: flex-start; }
  .hero__tagline,
  .hero__sub { margin-left: 0; margin-right: 0; }
  .stat { text-align: left; }
  .hero__portrait { width: 24rem; height: 24rem; }
  .grid--3 { grid-template-columns: repeat(3, 1fr); }
  .contact { grid-template-columns: 1fr 1fr; }
}

@media (min-width: 1280px) {
  .hero__title { font-size: 4.5rem; }
}