:root {
  --bg: #071018;
  --bg-2: #0c1824;
  --panel: #102132;
  --panel-2: #163044;
  --line: rgba(125, 211, 192, 0.16);
  --text: #eaf3f7;
  --muted: #93a8b8;
  --accent: #4ec4e0;
  --accent-2: #7dd3c0;
  --gold: #e0c36a;
  --danger: #ef8a7a;
  --shadow: 0 20px 50px rgba(0, 0, 0, 0.35);
  --radius: 18px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: "IBM Plex Sans Arabic", "Cairo", sans-serif;
  background:
    radial-gradient(1200px 500px at 90% -10%, rgba(78, 196, 224, 0.12), transparent 50%),
    radial-gradient(900px 400px at 0% 20%, rgba(125, 211, 192, 0.08), transparent 45%),
    var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.85;
}

a {
  color: var(--accent);
  text-decoration: none;
}

button,
input {
  font-family: inherit;
}

.app {
  display: grid;
  grid-template-columns: 300px 1fr;
  min-height: 100vh;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  overflow: auto;
  background: linear-gradient(180deg, #0d1c2b, #0a1622);
  border-left: 1px solid var(--line);
  padding: 28px 18px 40px;
}

.brand {
  display: flex;
  gap: 12px;
  align-items: center;
  margin-bottom: 22px;
}

.logo {
  width: 44px;
  height: 44px;
  border-radius: 14px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  display: grid;
  place-items: center;
  color: #06202a;
  font-weight: 700;
  box-shadow: 0 8px 24px rgba(78, 196, 224, 0.3);
}

.brand h1 {
  font-size: 18px;
  font-weight: 700;
}

.brand p {
  color: var(--muted);
  font-size: 12px;
}

.search {
  width: 100%;
  background: #0a1826;
  border: 1px solid var(--line);
  color: var(--text);
  border-radius: 12px;
  padding: 11px 12px;
  margin-bottom: 18px;
  outline: none;
}

.search:focus {
  border-color: var(--accent);
}

.nav-group {
  margin-bottom: 18px;
}

.nav-group h3 {
  font-size: 12px;
  color: var(--gold);
  margin-bottom: 8px;
  letter-spacing: 0.4px;
}

.nav-btn {
  width: 100%;
  text-align: right;
  background: transparent;
  border: 0;
  color: var(--muted);
  padding: 8px 10px;
  border-radius: 10px;
  cursor: pointer;
  font-size: 14px;
}

.nav-btn:hover,
.nav-btn.active {
  background: rgba(78, 196, 224, 0.12);
  color: var(--text);
}

.main {
  padding: 28px 36px 70px;
  max-width: 1100px;
}

.hero {
  background:
    linear-gradient(135deg, rgba(22, 48, 68, 0.85), rgba(16, 33, 50, 0.9)),
    repeating-linear-gradient(90deg, transparent, transparent 24px, rgba(125, 211, 192, 0.04) 25px);
  border: 1px solid var(--line);
  border-radius: 24px;
  padding: 36px;
  box-shadow: var(--shadow);
  margin-bottom: 24px;
}

.kicker {
  color: var(--accent-2);
  font-size: 13px;
  margin-bottom: 8px;
}

.hero h2 {
  font-size: 36px;
  line-height: 1.4;
  margin-bottom: 10px;
}

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

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 18px;
}

.chip {
  background: rgba(78, 196, 224, 0.1);
  border: 1px solid var(--line);
  color: var(--text);
  border-radius: 999px;
  padding: 6px 12px;
  font-size: 13px;
  cursor: pointer;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-bottom: 24px;
}

.card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px;
  cursor: pointer;
  min-height: 140px;
}

.card:hover {
  border-color: rgba(78, 196, 224, 0.4);
  transform: translateY(-2px);
  transition: 0.2s ease;
}

.card h3 {
  font-size: 18px;
  margin-bottom: 8px;
}

.card p {
  color: var(--muted);
  font-size: 14px;
}

.article {
  display: none;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 24px;
  padding: 30px;
}

.article.visible {
  display: block;
}

.article h2 {
  font-size: 30px;
  margin-bottom: 8px;
}

.meta {
  color: var(--muted);
  font-size: 13px;
  margin-bottom: 18px;
}

.article h3 {
  margin: 22px 0 8px;
  color: var(--accent-2);
}

.article p,
.article li {
  color: #d7e6ee;
  margin-bottom: 10px;
}

.article ul,
.article ol {
  padding-right: 22px;
  margin-bottom: 12px;
}

.callout {
  background: #163044;
  border-right: 4px solid var(--gold);
  border-radius: 12px;
  padding: 14px 16px;
  margin: 16px 0;
  color: #f2efe4;
}

.warn {
  border-right-color: var(--danger);
  background: #2a1b1c;
}

.diagram {
  background: #0a1826;
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 16px;
  margin: 16px 0 22px;
  overflow-x: auto;
}

.layers,
.flow,
.compare {
  display: grid;
  gap: 8px;
}

.layer {
  display: grid;
  grid-template-columns: 90px 1fr;
  gap: 10px;
  align-items: center;
  background: var(--panel-2);
  border-radius: 10px;
  padding: 8px 12px;
}

.layer b {
  color: var(--gold);
  font-size: 13px;
}

.flow {
  grid-template-columns: repeat(5, 1fr);
}

.flow div,
.box {
  background: var(--panel-2);
  border-radius: 12px;
  padding: 12px;
  text-align: center;
  font-size: 13px;
}

.compare {
  grid-template-columns: repeat(3, 1fr);
}

.term-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.term {
  background: #0a1826;
  border-radius: 12px;
  padding: 12px;
  border: 1px solid var(--line);
}

.term strong {
  display: block;
  margin-bottom: 4px;
  color: var(--accent);
}

.hidden {
  display: none !important;
}

.footer {
  margin-top: 18px;
  color: var(--muted);
  font-size: 13px;
}

@media (max-width: 980px) {
  .app {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: relative;
    height: auto;
    border-left: 0;
    border-bottom: 1px solid var(--line);
  }

  .grid,
  .flow,
  .compare,
  .term-list {
    grid-template-columns: 1fr;
  }

  .main {
    padding: 18px;
  }
}