:root {
  --bg: #f0f4f8;
  --card: #ffffff;
  --text: #1a202c;
  --muted: #4a5568;
  --accent: #0b5c8a;
  --accent-dark: #084766;
  --border: #cbd5e0;
  --ok: #276749;
  --warn: #b7791f;
  --bad: #c53030;
  --font-base: 1.25rem;
  --font-scale: 1;
  --radius: 16px;
  --shadow: 0 4px 14px rgba(0, 0, 0, 0.08);
}

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

html {
  font-size: calc(var(--font-base) * var(--font-scale));
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.55;
  color: var(--text);
  background: var(--bg);
}

a {
  color: var(--accent);
  text-decoration-thickness: 2px;
}

a:focus-visible,
button:focus-visible,
input:focus-visible,
textarea:focus-visible {
  outline: 3px solid #f6ad55;
  outline-offset: 2px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: #000;
  color: #fff;
  padding: 0.5rem 1rem;
  z-index: 100;
}

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

.site-header {
  background: var(--accent);
  color: #fff;
  padding: 1.25rem 1rem 1.5rem;
}

.site-header h1 {
  margin: 0 0 0.35rem;
  font-size: 1.35rem;
  line-height: 1.25;
}

.site-header p {
  margin: 0;
  font-size: 0.95rem;
  opacity: 0.95;
}

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 3rem;
  min-width: 3rem;
  padding: 0.65rem 1.25rem;
  border: 2px solid transparent;
  border-radius: 12px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  background: #fff;
  color: var(--accent-dark);
}

.btn-primary {
  background: #fff;
  color: var(--accent-dark);
}

.btn-secondary {
  background: var(--accent-dark);
  color: #fff;
  border-color: #fff;
}

.btn-ghost {
  background: transparent;
  color: #fff;
  border-color: rgba(255, 255, 255, 0.7);
}

main {
  max-width: 48rem;
  margin: 0 auto;
  padding: 1rem 1rem 3rem;
}

.disclaimer {
  background: #fffbeb;
  border: 2px solid #f6ad55;
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  margin-bottom: 1.25rem;
  font-size: 0.95rem;
}

.disclaimer strong {
  display: block;
  margin-bottom: 0.35rem;
}

nav.toc {
  margin-bottom: 1.5rem;
}

nav.toc ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.5rem;
}

nav.toc a {
  display: block;
  background: var(--card);
  padding: 0.85rem 1rem;
  border-radius: 12px;
  border: 2px solid var(--border);
  font-weight: 600;
  color: var(--text);
  text-decoration: none;
}

section.topic {
  margin-bottom: 2rem;
}

section.topic > h2 {
  font-size: 1.3rem;
  margin: 0 0 1rem;
  padding-bottom: 0.35rem;
  border-bottom: 3px solid var(--accent);
}

.card {
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.1rem 1.15rem;
  margin-bottom: 1rem;
}

.card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.15rem;
}

.card .number {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--accent);
  margin: 0.25rem 0 0.5rem;
}

.card p {
  margin: 0 0 0.75rem;
  color: var(--muted);
}

.status {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 700;
  padding: 0.2rem 0.55rem;
  border-radius: 8px;
  margin-bottom: 0.65rem;
}

.status-da-co-van-ban {
  background: #c6f6d5;
  color: var(--ok);
}

.status-can-giai-trinh {
  background: #feebc8;
  color: var(--warn);
}

.status-chua-kiem-chung {
  background: #fed7d7;
  color: var(--bad);
}

.card-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.btn-small {
  min-height: 2.75rem;
  padding: 0.5rem 1rem;
  font-size: 0.95rem;
  border-radius: 10px;
  border: 2px solid var(--accent);
  background: #fff;
  color: var(--accent);
  font-weight: 600;
  cursor: pointer;
}

.chart-wrap {
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 0.75rem;
  margin-bottom: 1rem;
  overflow-x: auto;
}

.chart-wrap svg {
  display: block;
  width: 100%;
  min-width: 320px;
  height: auto;
}

.matrix {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  background: var(--card);
  border-radius: var(--radius);
  overflow: hidden;
  border: 2px solid var(--border);
}

.matrix th,
.matrix td {
  border: 1px solid var(--border);
  padding: 0.5rem;
  text-align: center;
}

.matrix th:first-child,
.matrix td:first-child {
  text-align: left;
  min-width: 10rem;
}

.matrix .matrix-src {
  margin-top: 0.35rem;
}

.site-footer {
  text-align: center;
  padding: 1.5rem 1rem;
  font-size: 0.9rem;
  color: var(--muted);
}

/* Modal */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.55);
  display: none;
  align-items: flex-end;
  justify-content: center;
  z-index: 50;
  padding: 0;
}

.modal-backdrop.open {
  display: flex;
}

.modal {
  background: #fff;
  width: 100%;
  max-width: 32rem;
  max-height: 92vh;
  overflow: auto;
  border-radius: 20px 20px 0 0;
  padding: 1.25rem;
}

@media (min-width: 640px) {
  .modal-backdrop {
    align-items: center;
    padding: 1rem;
  }
  .modal {
    border-radius: var(--radius);
  }
}

.modal h2 {
  margin-top: 0;
  font-size: 1.2rem;
}

.modal label {
  display: block;
  font-weight: 600;
  margin: 0.75rem 0 0.35rem;
}

.modal input,
.modal textarea {
  width: 100%;
  font-size: 1rem;
  padding: 0.65rem;
  border: 2px solid var(--border);
  border-radius: 10px;
}

.modal textarea {
  min-height: 6rem;
  resize: vertical;
}

.modal .form-actions {
  display: flex;
  gap: 0.5rem;
  margin-top: 1rem;
  flex-wrap: wrap;
}

.form-msg {
  margin-top: 0.75rem;
  font-weight: 600;
}

.form-msg.ok {
  color: var(--ok);
}

.form-msg.err {
  color: var(--bad);
}

/* Sources popover */
.sources-panel {
  margin-top: 0.75rem;
  padding: 0.75rem;
  background: #edf2f7;
  border-radius: 10px;
  display: none;
}

.sources-panel.open {
  display: block;
}

.sources-panel ul {
  margin: 0;
  padding-left: 1.2rem;
}

.sources-panel li {
  margin-bottom: 0.35rem;
}