:root {
  --bg: #f5f7fb;
  --card-bg: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --primary: #4f46e5;
  --primary-dark: #3730a3;
  --border: #e5e7eb;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Segoe UI", "Sarabun", Tahoma, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
}

.container {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 20px;
}

.site-header {
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px;
  flex-wrap: wrap;
  gap: 10px;
}

.brand {
  font-weight: 700;
  text-decoration: none;
  color: var(--text);
  font-size: 1.1rem;
}

.nav a {
  margin-left: 18px;
  text-decoration: none;
  color: var(--muted);
  font-weight: 500;
  padding-bottom: 4px;
  border-bottom: 2px solid transparent;
}

.nav a.active,
.nav a:hover {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

main.container {
  padding-top: 32px;
  padding-bottom: 60px;
  min-height: calc(100vh - 160px);
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 32px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.04);
}

.hero {
  text-align: center;
}

.avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  object-fit: cover;
  margin-bottom: 12px;
  border: 3px solid var(--primary);
}

.student-id { color: var(--muted); }
.faculty, .university { margin: 2px 0; color: var(--muted); }
.intro { max-width: 520px; margin: 16px auto; }

.info-grid {
  display: flex;
  justify-content: center;
  gap: 30px;
  flex-wrap: wrap;
  margin: 20px 0;
}

.info-item {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.info-item .label { color: var(--muted); font-size: 0.85rem; }
.info-item .value { font-weight: 600; }
.info-item a { color: var(--primary); }

.cta-row {
  display: flex;
  gap: 12px;
  justify-content: center;
  margin-top: 20px;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 10px 20px;
  border-radius: 8px;
  background: var(--primary);
  color: #fff;
  text-decoration: none;
  font-weight: 600;
}

.btn:hover { background: var(--primary-dark); }

.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 1.5px solid var(--primary);
}

h1 { color: var(--primary-dark); }
h2 { margin-top: 28px; font-size: 1.2rem; color: var(--primary-dark); }

.tag-list { display: flex; flex-wrap: wrap; gap: 8px; }
.tag {
  background: #eef2ff;
  color: var(--primary-dark);
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 0.85rem;
}

.research-topic {
  font-size: 1.05rem;
  background: #eef2ff;
  padding: 14px 18px;
  border-radius: 10px;
}

.ref-list li { color: var(--muted); font-size: 0.92rem; margin-bottom: 6px; }

.site-footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.85rem;
  padding: 20px 0 40px;
}