/* ==============================================
   Yusheng Ding — Personal Website
   Palette: Warm Earth
   ============================================== */

:root {
  --primary-dark: #264653;
  --accent-warm: #f4a261;
  --accent-bold: #e76f51;
  --background: #faf3e8;
  --text: #2d2d2d;
  --light-teal: #2a9d8f;
  --card-bg: #fff8ef;
  --shadow-soft: 0 10px 30px rgba(38, 70, 83, 0.12);
  --shadow-strong: 0 16px 36px rgba(38, 70, 83, 0.2);
}

/* --- Reset & Base --- */

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.7;
  color: var(--text);
  background:
    radial-gradient(circle at 0% 0%, rgba(244, 162, 97, 0.15), transparent 32%),
    radial-gradient(circle at 100% 100%, rgba(42, 157, 143, 0.12), transparent 36%),
    var(--background);
}

.container {
  width: min(100% - 2rem, 52rem);
  margin: 0 auto;
}

/* --- Skip Link (accessibility) --- */

.skip-link {
  position: absolute;
  top: -100%;
  left: 1rem;
  padding: 0.5rem 1rem;
  background: var(--primary-dark);
  color: white;
  border-radius: 0 0 0.5rem 0.5rem;
  z-index: 100;
  border: none;
}

.skip-link:focus {
  top: 0;
}

/* --- Typography --- */

h1,
h2,
h3 {
  margin-top: 0;
  line-height: 1.2;
  color: var(--primary-dark);
}

h1 {
  margin-bottom: 0.5rem;
  font-size: clamp(2.2rem, 5vw, 3.2rem);
  letter-spacing: -0.02em;
}

h2 {
  margin-bottom: 1.2rem;
  font-size: clamp(1.4rem, 3vw, 1.9rem);
}

h3 {
  font-size: 1.1rem;
}

a {
  color: var(--primary-dark);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  transition: color 180ms ease, border-color 180ms ease;
}

a:hover,
a:focus-visible {
  color: var(--light-teal);
  border-color: var(--light-teal);
  outline: none;
}

/* --- Hero --- */

.hero {
  padding: 5rem 0 2.5rem;
}

.hero-content {
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: center;
  gap: 2.5rem;
}

.avatar {
  width: 10rem;
  height: 10rem;
  object-fit: cover;
  border-radius: 50%;
  border: 4px solid var(--accent-warm);
  box-shadow: var(--shadow-strong);
}

.tagline {
  margin: 0.25rem 0;
  font-size: 1.15rem;
  color: var(--text);
}

.tagline.bilingual {
  color: #c45a3e;
  font-weight: 600;
  font-size: 1.05rem;
}

/* --- Social Links (pills with icons) --- */

.social-links {
  margin-top: 1.5rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.social-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.45rem 0.9rem;
  border-radius: 99px;
  border: 1.5px solid rgba(38, 70, 83, 0.25);
  font-size: 0.88rem;
  font-weight: 500;
  transition: background 180ms ease, border-color 180ms ease, color 180ms ease, transform 150ms ease;
}

.social-pill:hover,
.social-pill:focus-visible {
  background: var(--primary-dark);
  color: white;
  border-color: var(--primary-dark);
  transform: translateY(-1px);
}

.social-pill svg {
  flex-shrink: 0;
}

/* --- Divider --- */

.divider {
  border: none;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(38, 70, 83, 0.15), transparent);
  margin: 0 auto;
  width: min(100% - 2rem, 52rem);
}

/* --- Sections --- */

section,
.footer {
  padding: 2.5rem 0;
}

.about p {
  max-width: 65ch;
  margin-bottom: 0.8rem;
}

.about p:last-child {
  margin-bottom: 0;
}

/* --- Project Grid --- */

.project-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.2rem;
}

.project-card {
  background: var(--card-bg);
  border: 1.5px solid rgba(38, 70, 83, 0.15);
  border-radius: 1rem;
  padding: 1.4rem;
  box-shadow: var(--shadow-soft);
  display: flex;
  flex-direction: column;
  transition: transform 200ms ease, box-shadow 200ms ease, border-color 200ms ease;
}

.project-card:hover,
.project-card:focus-within {
  transform: translateY(-4px);
  box-shadow: var(--shadow-strong);
  border-color: var(--accent-bold);
}

.project-card h3 {
  margin-bottom: 0.6rem;
  color: var(--primary-dark);
}

.project-card p {
  margin-bottom: 0;
  font-size: 0.95rem;
  line-height: 1.6;
  flex-grow: 1;
}

.project-card .project-link,
.project-card .project-links {
  margin-top: auto;
  padding-top: 1rem;
}

/* --- Project Link (styled as subtle button) --- */

.project-link {
  display: inline-block;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--light-teal);
  border-bottom: none;
  transition: color 180ms ease, transform 150ms ease;
}

.project-link:hover,
.project-link:focus-visible {
  color: var(--accent-bold);
  border-bottom: none;
  transform: translateX(3px);
}

.project-links {
  display: flex;
  gap: 1rem;
  align-items: center;
}

.project-link-secondary {
  color: var(--text);
  opacity: 0.65;
  font-weight: 500;
  font-size: 0.82rem;
}

.project-link-secondary:hover,
.project-link-secondary:focus-visible {
  opacity: 1;
  color: var(--light-teal);
  transform: none;
}

/* --- CTA --- */

.cta {
  text-align: center;
  padding: 3rem 0 2rem;
}

.cta-text {
  font-size: 1.1rem;
  color: var(--primary-dark);
  margin-bottom: 1rem;
}

.cta-pill {
  font-size: 0.95rem;
  padding: 0.6rem 1.4rem;
  border-width: 2px;
  border-color: var(--accent-bold);
  color: var(--accent-bold);
}

.cta-pill:hover,
.cta-pill:focus-visible {
  background: var(--accent-bold);
  color: white;
  border-color: var(--accent-bold);
}

/* --- Footer --- */

.footer {
  border-top: 1px solid rgba(38, 70, 83, 0.15);
  text-align: center;
  padding: 2rem 0;
}

.footer-tagline {
  font-weight: 600;
  color: var(--primary-dark);
  margin-bottom: 0.25rem;
}

.footer p:last-child {
  font-size: 0.85rem;
  color: rgba(45, 45, 45, 0.6);
}

/* --- Animations --- */

.section-fade {
  opacity: 0;
  transform: translateY(12px);
  animation: fade-in 600ms ease forwards;
}

#about {
  animation-delay: 150ms;
}

#projects {
  animation-delay: 250ms;
}

#footer {
  animation-delay: 350ms;
}

@keyframes fade-in {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* --- Responsive --- */

@media (max-width: 800px) {
  .hero {
    padding-top: 3rem;
  }

  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .avatar {
    margin-inline: auto;
    width: 8rem;
    height: 8rem;
  }

  .social-links {
    justify-content: center;
  }

  .project-grid {
    grid-template-columns: 1fr;
  }
}

/* tablet already 2-col from base rule */