:root {
  --bg: #0f1117;
  --bg2: #1a1d2e;
  --bg3: #232640;
  --accent: #4f8ef7;
  --accent2: #7c3aed;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --text: #e2e8f0;
  --text2: #94a3b8;
  --border: #2d3748;
  --card: #1e2235;
  --code-bg: #0d1117;
  --radius: 12px;
  --shadow: 0 4px 24px rgba(0,0,0,0.4);
}

.light {
  --bg: #f8fafc;
  --bg2: #f1f5f9;
  --bg3: #e2e8f0;
  --text: #1e293b;
  --text2: #64748b;
  --border: #cbd5e1;
  --card: #ffffff;
  --code-bg: #1e293b;
  --shadow: 0 4px 24px rgba(0,0,0,0.08);
}

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

/* Resets para elementos semánticos que tienen estilos de navegador */
figure       { margin: 0; }
address      { font-style: normal; }
output       { display: block; }
dl, dt, dd   { margin: 0; padding: 0; }
ul.algo-grid,
ul.rec-list  { list-style: none; padding: 0; }
pre          { margin: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: 'Segoe UI', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  transition: background 0.3s, color 0.3s;
}

/* ── Banner Institucional ── */
.inst-banner {
  background: #ffffff;
  border-bottom: 3px solid #004A8F;
  padding: 14px 24px;
}

.light .inst-banner {
  background: #ffffff;
}

.inst-inner {
  max-width: 960px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 20px;
}

.inst-logo {
  height: 58px;
  width: auto;
  object-fit: contain;
  flex-shrink: 0;
}

.inst-divider {
  width: 1px;
  height: 54px;
  background: #cbd5e1;
  flex-shrink: 0;
}

.inst-info {
  display: flex;
  flex-direction: column;
  gap: 3px;
  flex: 1;
}

.inst-row {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.inst-sep { color: #94a3b8; font-size: 0.8rem; }

.inst-facultad {
  font-size: 0.78rem;
  font-weight: 600;
  color: #004A8F;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.inst-programa {
  font-size: 0.78rem;
  color: #475569;
  font-weight: 500;
}

.inst-nombre {
  font-size: 1rem;
  font-weight: 700;
  color: #1e293b;
}

.inst-curso {
  font-size: 0.82rem;
  color: #1e293b;
  font-weight: 600;
}

.inst-nrc {
  font-size: 0.82rem;
  color: #64748b;
}

@media (max-width: 540px) {
  .inst-inner { flex-direction: column; align-items: flex-start; gap: 12px; }
  .inst-divider { display: none; }
  .inst-logo { height: 44px; }
}

/* ── Header ── */
header {
  background: linear-gradient(135deg, #0f1117 0%, #1a1d2e 50%, #232640 100%);
  padding: 60px 24px 40px;
  text-align: center;
  border-bottom: 1px solid var(--border);
  position: relative;
  overflow: hidden;
}

header::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 50% 0%, rgba(79,142,247,0.15) 0%, transparent 70%);
}

.header-badge {
  display: inline-block;
  background: rgba(79,142,247,0.15);
  border: 1px solid rgba(79,142,247,0.3);
  color: var(--accent);
  padding: 4px 14px;
  border-radius: 20px;
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 16px;
}

header h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 800;
  background: linear-gradient(135deg, #4f8ef7, #a78bfa);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  position: relative;
}

header p.subtitle {
  color: var(--text2);
  font-size: 1.1rem;
  margin-top: 12px;
  max-width: 600px;
  margin-inline: auto;
  position: relative;
}

/* ── Theme Toggle ── */
.theme-btn {
  position: fixed;
  top: 20px;
  right: 20px;
  z-index: 100;
  background: var(--card);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 8px 14px;
  border-radius: 20px;
  cursor: pointer;
  font-size: 0.85rem;
  transition: all 0.2s;
  box-shadow: var(--shadow);
}

.theme-btn:hover { background: var(--bg3); }

/* ── Sticky Nav ── */
nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(15,17,23,0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  overflow-x: auto;
}

.light nav { background: rgba(248,250,252,0.92); }

nav ul {
  display: flex;
  list-style: none;
  gap: 4px;
  min-width: max-content;
  padding: 10px 0;
}

nav a {
  display: block;
  padding: 8px 16px;
  color: var(--text2);
  text-decoration: none;
  border-radius: 8px;
  font-size: 0.88rem;
  font-weight: 500;
  transition: all 0.2s;
  white-space: nowrap;
}

nav a:hover, nav a.active {
  background: rgba(79,142,247,0.15);
  color: var(--accent);
}

/* ── Main Layout ── */
main {
  max-width: 860px;
  margin: 0 auto;
  padding: 40px 24px 80px;
}

/* ── Article Cards ── */
article {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px;
  margin-bottom: 40px;
  box-shadow: var(--shadow);
  scroll-margin-top: 70px;
}

.entry-number {
  font-size: 0.75rem;
  color: var(--accent);
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 8px;
}

article h2 {
  font-size: 1.7rem;
  font-weight: 700;
  margin-bottom: 8px;
  line-height: 1.3;
}

.entry-meta {
  display: flex;
  gap: 16px;
  color: var(--text2);
  font-size: 0.82rem;
  margin-bottom: 0;
}

article h3 {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--accent);
  margin: 28px 0 10px;
}

article p { margin-bottom: 16px; color: var(--text); }

article ul, article ol {
  padding-left: 20px;
  margin-bottom: 16px;
}

article li { margin-bottom: 8px; }

/* ── Highlight Box ── */
.highlight-box {
  background: rgba(79,142,247,0.08);
  border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0;
  padding: 16px 20px;
  margin: 20px 0;
  font-style: italic;
}

.highlight-box.warning {
  background: rgba(245,158,11,0.08);
  border-color: var(--warning);
}

.highlight-box.success {
  background: rgba(16,185,129,0.08);
  border-color: var(--success);
}

/* ── Article header (entry number + h2 + meta) ── */
article > header, #demo > header {
  margin-bottom: 28px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border);
}

article > header h2, #demo > header h2 { margin-bottom: 8px; }

/* ── Field label (non-input descriptive label in demo) ── */
p.field-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text2);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ── figcaption ── */
figcaption {
  text-align: center;
  font-size: 0.78rem;
  color: var(--text2);
  margin-top: 12px;
  font-style: italic;
}

/* ── pre.code-block ── */
pre.code-block {
  white-space: pre-wrap;
  word-break: break-all;
}

/* ── Diagram ── */
.diagram {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 24px;
  margin: 24px 0;
  overflow-x: auto;
}

.diagram-flow {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}

.diagram-box {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 18px;
  text-align: center;
  font-size: 0.85rem;
  font-weight: 600;
  min-width: 100px;
}

.diagram-box.key-pub { border-color: var(--accent); color: var(--accent); }
.diagram-box.key-priv { border-color: var(--accent2); color: var(--accent2); }
.diagram-box.data { border-color: var(--success); color: var(--success); }
.diagram-box.cipher { border-color: var(--warning); color: var(--warning); }

.arrow {
  color: var(--text2);
  font-size: 1.4rem;
  font-weight: 300;
}

/* ── Comparison Table ── */
.table-wrap { overflow-x: auto; margin: 24px 0; }

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

th {
  background: var(--bg3);
  padding: 12px 16px;
  text-align: left;
  font-weight: 600;
  border: 1px solid var(--border);
}

th:first-child { color: var(--text2); }
th.sym { color: var(--warning); }
th.asym { color: var(--accent); }

td {
  padding: 11px 16px;
  border: 1px solid var(--border);
  vertical-align: top;
}

tr:nth-child(even) td { background: rgba(255,255,255,0.02); }

td .badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 12px;
  font-size: 0.78rem;
  font-weight: 600;
}

.badge.green { background: rgba(16,185,129,0.15); color: var(--success); }
.badge.yellow { background: rgba(245,158,11,0.15); color: var(--warning); }
.badge.red { background: rgba(239,68,68,0.15); color: var(--danger); }

/* ── Code Block ── */
.code-block {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 20px;
  margin: 16px 0;
  overflow-x: auto;
  font-family: 'Cascadia Code', 'Fira Code', 'Consolas', monospace;
  font-size: 0.83rem;
  line-height: 1.6;
  color: #e2e8f0;
}

.code-block .kw { color: #7c3aed; }
.code-block .fn { color: #4f8ef7; }
.code-block .str { color: #10b981; }
.code-block .cm { color: #64748b; }
.code-block .num { color: #f59e0b; }

/* ── Algorithm Cards ── */
.algo-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  margin: 20px 0;
}

.algo-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px;
}

.algo-card h4 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.algo-card.rsa h4 { color: var(--accent); }
.algo-card.ecc h4 { color: var(--success); }
.algo-card.elgamal h4 { color: var(--warning); }
.algo-card.dsa h4 { color: var(--accent2); }

.algo-card p { font-size: 0.85rem; color: var(--text2); margin: 0; }

/* ── Demo Section ── */
#demo {
  background: var(--card);
  border: 1px solid rgba(79,142,247,0.3);
  border-radius: var(--radius);
  padding: 40px;
  margin-bottom: 40px;
  scroll-margin-top: 70px;
  box-shadow: 0 0 40px rgba(79,142,247,0.08);
}

#demo h2 { margin-bottom: 8px; }

.demo-tabs {
  display: flex;
  gap: 8px;
  margin: 24px 0 20px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0;
}

.tab-btn {
  padding: 10px 20px;
  background: none;
  border: none;
  color: var(--text2);
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 500;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
  transition: all 0.2s;
}

.tab-btn.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.tab-content { display: none; }
.tab-content.active { display: block; }

.demo-area {
  display: grid;
  gap: 16px;
}

label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text2);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

input[type="text"], textarea {
  width: 100%;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px 14px;
  color: var(--text);
  font-size: 0.9rem;
  font-family: inherit;
  transition: border-color 0.2s;
  resize: vertical;
}

input[type="text"]:focus, textarea:focus {
  outline: none;
  border-color: var(--accent);
}

.output-box {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
  font-family: 'Cascadia Code', monospace;
  font-size: 0.78rem;
  color: #94a3b8;
  word-break: break-all;
  min-height: 60px;
  white-space: pre-wrap;
}

.output-box.success { border-color: var(--success); color: var(--success); }
.output-box.error { border-color: var(--danger); color: var(--danger); }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 22px;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 600;
  transition: all 0.2s;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), #6366f1);
  color: white;
}

.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 4px 16px rgba(79,142,247,0.4); }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; transform: none; }

.btn-secondary {
  background: var(--bg3);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover { background: var(--bg2); }

.btn-group { display: flex; gap: 10px; flex-wrap: wrap; }

.spinner {
  width: 16px; height: 16px;
  border: 2px solid rgba(255,255,255,0.3);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
  display: none;
}

@keyframes spin { to { transform: rotate(360deg); } }

.status-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 500;
  margin-top: 8px;
  min-height: 0;
}

.status-bar:empty { display: none; }

.status-bar.info { background: rgba(79,142,247,0.1); color: var(--accent); }
.status-bar.ok { background: rgba(16,185,129,0.1); color: var(--success); }
.status-bar.err { background: rgba(239,68,68,0.1); color: var(--danger); }

.key-display {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
}

.key-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 12px;
}

.key-row:last-child { margin-bottom: 0; }

.key-label {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  min-width: 80px;
}

.key-label.pub { color: var(--accent); }
.key-label.priv { color: var(--accent2); }

.key-value {
  font-family: monospace;
  font-size: 0.72rem;
  color: var(--text2);
  word-break: break-all;
  flex: 1;
  line-height: 1.5;
  max-height: 80px;
  overflow-y: auto;
}

.copy-btn {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 10px;
  color: var(--text2);
  cursor: pointer;
  font-size: 0.75rem;
  white-space: nowrap;
  transition: all 0.15s;
}

.copy-btn:hover { color: var(--text); background: var(--border); }

/* ── Recommendations ── */
.rec-list {
  display: grid;
  gap: 12px;
  margin: 20px 0;
}

.rec-item {
  display: flex;
  gap: 14px;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px;
}

.rec-icon {
  font-size: 1.4rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.rec-item h4 { font-size: 0.95rem; margin-bottom: 4px; }
.rec-item p { font-size: 0.85rem; color: var(--text2); margin: 0; }

/* ── Footer ── */
footer {
  text-align: center;
  padding: 32px 24px;
  color: var(--text2);
  font-size: 0.85rem;
  border-top: 1px solid var(--border);
}

/* ── Responsive ── */
@media (max-width: 640px) {
  article { padding: 24px 18px; }
  #demo { padding: 24px 18px; }
  .diagram-flow { flex-direction: column; }
  .arrow { transform: rotate(90deg); }
}