/* Shared design tokens & reset — David Jin portfolio */
:root {
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  line-height: 1.6;
}

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

[hidden] { display: none !important; }

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

button { font-family: inherit; cursor: pointer; }

.container {
  width: min(1080px, 92vw);
  margin-inline: auto;
}

.section {
  padding: 88px 0;
}

.section-title {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 12px;
}

.section-sub {
  font-size: 1.05rem;
  opacity: 0.72;
  max-width: 560px;
  margin: 0 0 40px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  border-radius: 10px;
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid transparent;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}

.btn:hover { transform: translateY(-1px); }

.btn-primary { background: var(--accent, #4f46e5); color: #fff; }
.btn-primary:hover { box-shadow: 0 6px 20px rgba(0,0,0,0.15); }

.btn-ghost { border-color: currentColor; background: transparent; }