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

:root {
  --bg: #f5f7fb;
  --white: #ffffff;
  --line: #dbe3ee;
  --text: #1f2937;
  --muted: #6b7280;
  --primary: #2563eb;
  --primary-soft: #eaf2ff;
  --shadow: 0 12px 30px rgba(0, 0, 0, 0.08);
  --radius: 18px;
}

body {
  font-family: Arial, Helvetica, sans-serif;
  background: linear-gradient(180deg, #f8fbff 0%, #f2f5fa 100%);
  color: var(--text);
  min-height: 100vh;
}

/* Header */
.site-header {
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(8px);
}

.header-wrap {
  min-height: 78px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  padding: 14px 0;
}

.site-title {
  font-size: 1.8rem;
  margin-bottom: 4px;
}

.site-subtitle {
  color: var(--muted);
  font-size: 0.95rem;
}

.header-badge {
  display: inline-block;
  padding: 10px 14px;
  border-radius: 999px;
  background: var(--primary-soft);
  color: var(--primary);
  border: 1px solid #cfe0ff;
  font-size: 0.9rem;
  font-weight: bold;
}

/* Hero */
.hero {
  padding: 48px 0 28px;
}

.hero-box {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 24px;
  padding: 34px;
  box-shadow: var(--shadow);
}

.hero-box h2 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  line-height: 1.15;
  margin-bottom: 14px;
}

.hero-box h2 span {
  color: var(--primary);
}

.hero-box p {
  color: var(--muted);
  line-height: 1.7;
  max-width: 760px;
}

/* Topics */
.topics-section {
  padding: 10px 0 70px;
}

.section-head {
  margin-bottom: 22px;
}

.section-head h3 {
  font-size: 1.35rem;
  margin-bottom: 6px;
}

.section-head p {
  color: var(--muted);
}

.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 340px));
  gap: 22px;
}

.topic-card {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}

.topic-card:hover {
  transform: translateY(-5px);
  border-color: #bfd4ff;
  box-shadow: 0 16px 35px rgba(37, 99, 235, 0.12);
}

.card-tag {
  display: inline-block;
  margin-bottom: 12px;
  padding: 6px 10px;
  font-size: 0.78rem;
  font-weight: bold;
  border-radius: 999px;
  background: #eef6ff;
  color: var(--primary);
}

.topic-card h4 {
  font-size: 1.2rem;
  margin-bottom: 12px;
}

.topic-card p {
  color: var(--muted);
  line-height: 1.65;
  margin-bottom: 18px;
}

.card-btn {
  border: none;
  background: var(--primary);
  color: #fff;
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 0.92rem;
  font-weight: bold;
  cursor: pointer;
}

.card-btn:hover {
  opacity: 0.92;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 24px 0 36px;
  color: var(--muted);
  font-size: 0.92rem;
  text-align: center;
  background: #fff;
}

/* Modal Bootstrap personalizada */
.topic-modal .modal-content {
  border: none;
  border-radius: 20px;
  background: #ffffff;
  overflow: hidden;
}

.topic-modal .modal-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: #ffffff;
  border-bottom: 1px solid var(--line);
  padding: 16px 20px;
}

.topic-modal .modal-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
}

.topic-modal .modal-body {
  padding: 24px 20px 40px;
}

.topic-content {
  width: min(900px, 100%);
  margin: 0 auto;
  line-height: 1.7;
}

.topic-content p,
.topic-content li {
  color: #4b5563;
  margin-bottom: 10px;
}

.topic-content h5 {
  margin: 18px 0 10px;
  color: var(--primary);
  font-size: 1rem;
}

.topic-content ul {
  padding-left: 20px;
  margin-bottom: 10px;
}

.topic-content hr {
  border: none;
  border-top: 1px solid #e5e7eb;
  margin: 18px 0;
  opacity: 1;
}

.topic-content pre {
  margin: 12px 0;
  background: #f8fafc;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 14px;
  overflow-x: auto;
}

.topic-content code {
  font-family: Consolas, Monaco, monospace;
  color: #111827;
  font-size: 0.95rem;
}

/* Responsive */
@media (max-width: 640px) {

  .hero-box,
  .topic-card {
    padding: 18px;
  }

  .site-title {
    font-size: 1.45rem;
  }

  .hero-box h2 {
    font-size: 1.75rem;
  }

  .cards-grid {
    grid-template-columns: 1fr;
  }

  .topic-modal .modal-header,
  .topic-modal .modal-body {
    padding-left: 14px;
    padding-right: 14px;
  }
}

.modal-dialog {
  border-radius: 5px;

}

.modal-header {
  background-color: #988;
}

.topic-modal iframe {
  border: 0;
  display: block;
}