/* hieu single theme (chiang: light, navy + teal, numbered sidebar) */

:root {
  --font-sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto,
               "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
               "Liberation Mono", monospace;
  --bg: #f7f6f2;
  --fg: #0a192f;
  --fg-soft: #33415c;
  --muted: #5a6a8a;
  --accent: #0f9e8a;
  --accent-contrast: #f7f6f2;
  --border: #e3e1d8;
  --card: #ffffff;
  --chip-bg: #e9f6f3;
  --ok: #0f9e8a;
  --content-w: 640px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--fg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; transition: color 0.15s ease; }
a:hover { color: var(--accent); }

/* ---------- header (mobile) ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: flex-end;
  padding: 0.9rem 1.5rem;
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.nav-links { display: flex; gap: 1.4rem; font-size: 0.95rem; }
.nav-links a { color: var(--muted); }
.nav-links a:hover { color: var(--fg); }

/* ---------- sidebar (desktop) ---------- */
.sidebar { display: none; }

/* ---------- layout ---------- */
.content { max-width: var(--content-w); margin: 0 auto; padding: 2.5rem 1.5rem 4rem; }

.section { margin-top: 4.25rem; scroll-margin-top: 5rem; }
.content > .section:first-child { margin-top: 0; }
.section-sub { color: var(--muted); font-size: 0.95rem; margin-bottom: 1.6rem; }

.section-title {
  font-size: 1.75rem;
  font-weight: 750;
  letter-spacing: -0.02em;
  margin-bottom: 1.35rem;
  display: flex; align-items: baseline; gap: 0.8rem;
}
.sec-num { display: inline; color: var(--accent); font-size: 1.05rem; font-family: var(--font-mono); font-weight: 400; }

.section p { margin-bottom: 1rem; color: var(--fg-soft); }

/* ---------- projects ---------- */
.projects { display: grid; grid-template-columns: 1fr; gap: 1.1rem; }

.project {
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.3rem 1.5rem;
  background: var(--card);
  transition: transform 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
}
.project:hover { transform: translateY(-2px); border-color: var(--accent); box-shadow: 0 8px 28px rgba(10, 25, 47, 0.1); }

.project-head { display: flex; align-items: center; gap: 0.6rem; margin-bottom: 0.45rem; }
.project-head h3 { flex: 1; font-size: 1.08rem; letter-spacing: -0.01em; }
.project-ico { font-size: 1.05rem; line-height: 1; }
.project-desc { font-size: 0.93rem; color: var(--fg-soft); margin-bottom: 0.8rem; }

.project-proof { list-style: none; display: grid; gap: 0.35rem; margin: 0 0 0.9rem; }
.project-proof li { color: var(--muted); font-size: 0.8rem; padding-left: 1rem; position: relative; }
.project-proof li::before { content: "✓"; color: var(--ok); position: absolute; left: 0; }

.project-stack { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.project-stack span {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--accent);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.14rem 0.6rem;
  background: var(--chip-bg);
}

.project-demo {
  margin: 1rem -1.5rem -1.3rem; padding: 0.9rem 1.5rem 1rem;
  border-top: 1px solid var(--border);
  background: color-mix(in srgb, var(--card) 70%, var(--bg));
}
.demo-preview { display: grid; grid-template-columns: repeat(auto-fit,minmax(130px,1fr)); gap: 0.4rem; }
.demo-preview span {
  min-height: 40px; display: flex; align-items: center; padding: 0.5rem 0.65rem;
  border: 1px solid var(--border); border-radius: 7px; color: var(--fg-soft);
  font-family: var(--font-mono); font-size: 0.68rem;
}
.demo-command {
  margin: 0.7rem 0 0; padding: 0.75rem; overflow-x: auto; border-radius: 7px;
  background: var(--bg); color: var(--fg-soft); font: 0.72rem/1.55 var(--font-mono); white-space: pre-wrap;
}
.demo-link, .demo-label {
  display: inline-flex; margin-top: 0.75rem; color: var(--accent); font: 0.72rem var(--font-mono);
}
.demo-link::after { content: " ↗"; }

/* ---------- contact ---------- */
.contact-line { font-size: 1.15rem; font-weight: 600; }
.contact-links { display: flex; align-items: center; gap: 1.6rem; flex-wrap: wrap; margin-top: 0.8rem; }
.contact-cta {
  font-weight: 750; font-size: 1.1rem;
  border-bottom: 2px solid var(--accent); padding-bottom: 2px;
}
.icon-link { display: inline-flex; align-items: center; gap: 0.45rem; }

/* ---------- footer ---------- */
.site-footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.8rem;
  padding: 2rem 1.5rem 3rem;
  border-top: 1px solid var(--border);
}

@media (min-width: 1024px) {
  .site-header { display: none; }

  .sidebar {
    display: block;
    position: fixed; top: 0; left: 0; bottom: 0;
    width: 300px;
    background: #ffffff;
    border-right: 1px solid var(--border);
    overflow-y: auto;
  }
  .sidebar-inner {
    display: flex; flex-direction: column; gap: 1.6rem;
    padding: 2.5rem 2rem;
    height: 100%;
  }
  .logo { font-weight: 800; font-size: 1.2rem; letter-spacing: -0.03em; }
  .logo-dot { color: var(--accent); }
  .sidebar-tag { color: var(--muted); font-size: 0.9rem; line-height: 1.5; }
  .sidebar-nav { display: flex; flex-direction: column; gap: 0.35rem; }
  .sidebar-nav a {
    color: var(--fg-soft); font-size: 0.95rem;
    padding: 0.38rem 0.6rem; border-radius: 8px;
    transition: color 0.15s ease, background 0.15s ease;
  }
  .sidebar-nav a span {
    font-family: var(--font-mono); font-size: 0.75rem; color: var(--accent);
    margin-right: 0.65rem;
  }
  .sidebar-nav a:hover { color: var(--fg); background: #f3f2ec; }
  .sidebar-socials {
    margin-top: auto;
    display: flex; flex-direction: column; gap: 0.5rem;
    font-family: var(--font-mono); font-size: 0.78rem; color: var(--muted);
  }
  .sidebar-socials a:hover { color: var(--accent); }

  .content {
    margin-left: 300px;
    max-width: 960px;
    padding: 2.5rem 3.5rem 4rem;
  }
  .projects { grid-template-columns: repeat(2, 1fr); }
  .project { box-shadow: 0 1px 3px rgba(10, 25, 47, 0.06); }
  .section { margin-top: 5.75rem; scroll-margin-top: 2rem; }
  .site-footer { margin-left: 300px; }
}

@media (max-width: 600px) {
  .nav-links { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; animation: none !important; }
}