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

:root {
  --background: #f4f7fb;
  --surface: #ffffff;
  --text: #172033;
  --muted: #6b7280;
  --border: #e5e7eb;
  --navy: #172b4d;
  --navy-light: #24436f;
  --accent: #2563eb;
  --accent-soft: #eff6ff;
  --shadow: 0 8px 24px rgba(15, 23, 42, 0.08);
}

body {
  font-family: Arial, Helvetica, sans-serif;
  background: var(--background);
  color: var(--text);
  line-height: 1.6;
}

.hero {
  background: linear-gradient(
    135deg,
    var(--navy),
    var(--navy-light)
  );
  color: #ffffff;
  padding: 55px 20px;
}

.hero-content {
  max-width: 900px;
  margin: 0 auto;
  text-align: center;
}

.hero h1 {
  font-size: 38px;
  margin-bottom: 10px;
}

.hero p {
  color: #dce4ef;
  margin-bottom: 25px;
  font-size: 17px;
}

#searchInput {
  width: 100%;
  max-width: 620px;
  padding: 15px 18px;
  border: none;
  border-radius: 10px;
  font-size: 16px;
  background: #ffffff;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
}

#searchInput:focus {
  outline: 3px solid rgba(255, 255, 255, 0.3);
}

.container {
  width: 92%;
  max-width: 1120px;
  margin: 40px auto;
}

.categories {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.card {
  background: var(--surface);
  border-radius: 16px;
  padding: 26px;
  box-shadow: var(--shadow);
  border: 1px solid transparent;
  transition:
    transform 0.25s ease,
    box-shadow 0.25s ease,
    border-color 0.25s ease;
}

.card:hover {
  transform: translateY(-6px);
  box-shadow: 0 14px 30px rgba(15, 23, 42, 0.12);
  border-color: #dbeafe;
}

.card h2 {
  margin-bottom: 16px;
  font-size: 22px;
}

.card ul {
  list-style: none;
}

.card li {
  border-bottom: 1px solid var(--border);
}

.card li:last-child {
  border-bottom: none;
}

.guide-btn {
  width: 100%;
  background: none;
  border: none;
  padding: 11px 0;
  font-size: 16px;
  cursor: pointer;
  text-align: left;
  color: var(--text);
  transition:
    color 0.2s ease,
    transform 0.2s ease;
}

.guide-btn::before {
  content: "›";
  color: var(--accent);
  margin-right: 10px;
  font-weight: bold;
}

.guide-btn:hover {
  color: var(--accent);
  transform: translateX(4px);
}

.guide-panel {
  position: relative;
  margin-top: 32px;
  background: var(--surface);
  padding: 32px;
  border-radius: 16px;
  border-left: 5px solid var(--accent);
  box-shadow: var(--shadow);
  animation: fadeIn 0.3s ease;
}

.guide-panel h2 {
  color: var(--accent);
  margin-bottom: 18px;
  padding-right: 100px;
}

.guide-panel ol {
  margin-left: 22px;
}

.guide-panel li {
  margin-bottom: 12px;
}

#closeGuide {
  position: absolute;
  top: 24px;
  right: 24px;
  padding: 9px 15px;
  border: none;
  background: #1f2937;
  color: #ffffff;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 600;
  transition:
    background 0.2s ease,
    transform 0.2s ease;
}

#closeGuide:hover {
  background: var(--accent);
  transform: translateY(-1px);
}

.hidden {
  display: none;
}

.no-results {
  grid-column: 1 / -1;
  text-align: center;
  background: var(--surface);
  color: var(--muted);
  padding: 35px;
  border-radius: 12px;
  box-shadow: var(--shadow);
}

footer {
  text-align: center;
  padding: 25px 20px;
  margin-top: 50px;
  color: var(--muted);
  font-size: 14px;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 900px) {
  .categories {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 600px) {
  .hero {
    padding: 42px 18px;
  }

  .hero h1 {
    font-size: 30px;
  }

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

  .guide-panel {
    padding: 24px;
  }

  .guide-panel h2 {
    padding-right: 0;
    margin-top: 45px;
  }

  #closeGuide {
    top: 18px;
    right: 18px;
  }
}