:root {
  --accent: #004aad;
  --accent-2: #ffcc00;
  --bg: #f6f8fb;
  --card: #ffffff;
  --muted: #6b7280;
  --radius: 14px;
}
* {
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
}
a {
  color: var(--accent);
  text-decoration: none;
}
body {
  font-family: Inter, Segoe UI, Roboto, Arial, sans-serif;
  margin: 0;
  background: var(--bg);
  color: #0f172a;
  line-height: 1.5;
}

/* Header */
header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;

  background: linear-gradient(90deg, #000, #ff0066);
  color: white;
  padding: 10px 20px;
  z-index: 999;
  box-shadow: 0 6px 30px rgba(3, 7, 18, 0.12);
}
.nav {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand {
  font-weight: 800;
}
.brand img {
  height: 80px;
  width: auto;
  border-radius: 8px;
}
.menu {
  display: flex;
  gap: 10px;
  align-items: center;
}
.menu a {
  color: rgba(255, 255, 255, 0.95);
  text-decoration: none;
  padding: 8px 10px;
  border-radius: 8px;
  font-weight: 600;
}
.menu a.active,
.menu a:hover {
  background: rgba(255, 255, 255, 0.06);
  color: var(--accent-2);
}

main {
  padding-top: 82px;
}
.wrap {
  max-width: 1200px;
  margin: 40px auto;
  padding: 0 20px;
}
.tabs {
  display: flex;
  
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 12px;
  justify-content: space-around;
}

/* Hero */
.hero {
  min-height: 56vh;
  background-image: url("https://via.placeholder.com/1400x600");
  background-size: cover;
  background-position: center;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 48px 20px;
  border-radius: 16px;
}
.hero-inner {
  max-width: 1000px;

  background-image: url("../img/bg.jpg");
  background-size: cover;
  background-position: center;

  padding: 28px;
  border-radius: 12px;
  color: white;
  text-align: center;
}
.hero h1 {
  font-size: clamp(1.6rem, 3.5vw, 2.6rem);
  margin: 0 0 8px;
}
.hero p {
  text-align: justify;
  font-size: clamp(1rem, 2.5vw, 1.2rem);
  margin: 0 0 16px;
  color: rgba(255, 255, 255, 0.85);
  font-weight: 600;
  text-shadow: 0 5px 10px #ff0066d2;
}
.cta {
  display: inline-block;
  background: var(--accent-2);
  color: #04203b;
  padding: 10px 16px;
  border-radius: 999px;
  font-weight: 700;
  text-decoration: none;
  margin-top: 12px;
}

/* Sections */
section {
  margin-bottom: 36px;
}
.card {
  background: var(--card);
  padding: 20px;
  border-radius: var(--radius);
  box-shadow: 0 10px 30px rgba(8, 15, 30, 0.06);
}

/* About */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 22px;
  align-items: center;
}
.avatar {
  width: 100%;
  height: 100%;
  max-height: 360px;
  object-fit: cover;
  border-radius: 12px;
}

/* benefits */
.benefits {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
}
.benefit {
  background: linear-gradient(180deg, #fff, #fbfdff);
  padding: 14px;
  border-radius: 12px;
}

/* Learning area */
.tabs {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}
.tab {
  background: var(--card);
  padding: 8px 12px;
  border-radius: 10px;
  cursor: pointer;
  border: 1px solid rgba(15, 23, 42, 0.04);
}
.tab.active {
  border-color: var(--accent);
  box-shadow: 0 8px 26px rgba(0, 74, 173, 0.06);
}
.panels {
  margin-top: 10px;
}

.two-col {
  display: grid;
  grid-template-columns: 1fr 360px;
  gap: 20px;
}

/* Accordion */
.accordion {
  border-radius: 10px;
  overflow: hidden;
}
.acc-item {
  border-bottom: 1px solid rgba(15, 23, 42, 0.06);
  padding: 12px;
}
.acc-title {
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
}
.acc-body {
  margin-top: 8px;
  display: none;
}

table {
  width: 100%;
  border-collapse: collapse;
  background: var(--card);
  border-radius: 10px;
  overflow: hidden;
}
th,
td {
  padding: 10px 12px;
  text-align: left;
  border-bottom: 1px solid rgba(15, 23, 42, 0.04);
}
th {
  background: linear-gradient(90deg, rgba(0, 74, 173, 0.06), transparent);
  font-weight: 700;
}
td small {
  color: var(--muted);
}

pre {
  padding: 12px;
  border-radius: 8px;
  overflow: auto;
  background: #0b1220;
  color: #e6eef8;
}
.code-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
}
.btn {
  background: var(--accent);
  color: white;
  padding: 8px 12px;
  border-radius: 8px;
  border: none;
  cursor: pointer;
}
.btn.secondary {
  background: #eef2ff;
  color: var(--accent);
  font-weight: 700;
}

/* variable naming table highlight */
.good {
  background: linear-gradient(90deg, rgba(34, 197, 94, 0.08), transparent);
}
.bad {
  background: linear-gradient(90deg, rgba(239, 68, 68, 0.06), transparent);
}

/* small helpers */
.muted {
  color: var(--muted);
}

/* footer */
footer {
  margin-top: 36px;
  padding: 28px 20px;
  text-align: center;
  color: #fff;
   background: linear-gradient(90deg, #000, #ff0066);
}

/* responsive */
@media (max-width: 900px) {
  .about-grid,
  .two-col {
    grid-template-columns: 1fr;
  }
  .menu {
    display: none;
  }
}

/* back to top */
#backTop {
  position: fixed;
  right: 20px;
  bottom: 20px;
  background: var(--accent);
  color: white;
  border: none;
  padding: 12px;
  border-radius: 999px;
  cursor: pointer;
  box-shadow: 0 8px 20px rgba(3, 7, 18, 0.16);
  display: none;
}