:root {
  --green: #2e7d32;
  --green-light: #4caf50;
  --green-bg: #f3f7f4;
  --ink: #1b3a2b;
  --muted: #5b6b61;
  --card: #ffffff;
  --border: #d7e6db;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
    Arial, sans-serif;
  color: var(--ink);
  background: var(--green-bg);
  line-height: 1.6;
}

a { color: var(--green); }

/* ---------- top bar ---------- */
.topbar {
  background: linear-gradient(135deg, #66bb6a, #1b5e20);
  color: #fff;
  padding: 28px 20px;
}
.topbar-inner {
  max-width: 820px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 16px;
}
.topbar img { width: 56px; height: 56px; border-radius: 14px; }
.topbar h1 { margin: 0; font-size: 1.5rem; font-weight: 800; }
.topbar .sub { margin: 2px 0 0; opacity: 0.9; font-size: 0.95rem; }

/* ---------- language switch ---------- */
.lang-switch {
  max-width: 820px;
  margin: 18px auto 0;
  padding: 0 20px;
  display: flex;
  gap: 8px;
}
.lang-switch button {
  border: 1px solid var(--border);
  background: #fff;
  color: var(--muted);
  border-radius: 999px;
  padding: 7px 16px;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.15s;
}
.lang-switch button.active {
  background: var(--green);
  color: #fff;
  border-color: var(--green);
}

/* ---------- content ---------- */
main {
  max-width: 820px;
  margin: 0 auto;
  padding: 24px 20px 64px;
}
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 28px 28px 32px;
  box-shadow: 0 4px 18px rgba(27, 94, 32, 0.06);
}
h2 { font-size: 1.9rem; font-weight: 800; margin: 0 0 4px; }
h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin: 28px 0 8px;
  color: var(--green);
}
h4 {
  font-size: 1.02rem;
  font-weight: 700;
  margin: 18px 0 6px;
  color: var(--green);
}
.updated { color: var(--muted); font-size: 0.9rem; margin: 0 0 20px; }
p { margin: 0 0 12px; }
ul { margin: 0 0 12px; padding-left: 22px; }
li { margin-bottom: 6px; }

/* language visibility (default English) */
.content-vi { display: none; }
html.vi .content-en { display: none; }
html.vi .content-vi { display: block; }

/* ---------- landing ---------- */
.hero { text-align: center; }
.hero .badge-row {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 22px;
}
.btn {
  display: inline-block;
  background: var(--green);
  color: #fff;
  text-decoration: none;
  padding: 13px 24px;
  border-radius: 999px;
  font-weight: 700;
}
.btn.secondary { background: #fff; color: var(--green); border: 1px solid var(--border); }

/* ---------- footer ---------- */
footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.88rem;
  padding: 24px 20px 40px;
}
footer a { color: var(--green); }