/* ─── Reset & Base ───────────────────────────────────────────────────────── */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  font-family: 'Segoe UI', Arial, sans-serif;
  background: #fafafa;
  color: #222;
  line-height: 1.6;
}

/* ─── Header ──────────────────────────────────────────────────────────────── */
header {
  background: #111;
  padding: 12px 24px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.5);
}
.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo-container {
  display: flex;
  align-items: center;
}
.logo-img {
  height: 48px;
  margin-right: 12px;
}
.brand-name {
  font-size: 1.8rem;
  font-weight: 700;
  background: linear-gradient(90deg, #FFD700, #FF4C4C);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  text-shadow: 1px 1px 4px rgba(0,0,0,0.4);
}
nav ul {
  list-style: none;
  display: flex;
}
nav li + li {
  margin-left: 24px;
}
nav a {
  color: #fff;
  text-decoration: none;
  font-weight: 500;
  transition: color .2s;
}
nav a:hover {
  color: #FFD700;
}

/* ─── Subject Title ──────────────────────────────────────────────────────── */
.subject-name {
  text-align: center;
  margin: 32px 0 16px;
}
.subject-name h1 {
  font-size: 2.8rem;
}

/* ─── Key Features ───────────────────────────────────────────────────────── */
.key-features {
  max-width: 800px;
  margin: 0 auto 32px;
  padding: 16px 24px;
  background: #fff5f5;
  border-left: 6px solid #b30000;
  border-radius: 6px;
}
.key-features ul {
  list-style: none;
}
.key-features li {
  margin: 0.6rem 0;
  font-size: 1.15rem;
  color: #b30000;
}

/* ─── Grid ───────────────────────────────────────────────────────────────── */
.grid-container {
  display: grid;
  grid-template-columns: repeat(3,1fr);
  gap: 18px;
  max-width: 840px;
  margin: 0 auto 48px;
  padding: 0 12px;
}
.grid-item {
  background: #fff;
  border: 2px solid #ddd;
  padding: 24px;
  text-align: center;
  font-size: 1.1rem;
  font-weight: 600;
  border-radius: 8px;
  transition: transform .2s, box-shadow .2s, border-color .2s;
}
.grid-item:hover {
  transform: translateY(-4px);
  box-shadow: 0 6px 12px rgba(0,0,0,0.1);
  border-color: #FF4C4C;
}

/* ─── About Section & SVG ───────────────────────────────────────────────── */
.about-section {
  max-width: 800px;
  margin: 48px auto;
  padding: 0 24px;
  text-align: center;
}
.about-section h2 {
  font-size: 2.2rem;
  margin-bottom: 16px;
}
.about-section p {
  margin: 12px 0;
  color: #444;
}
.svg-wrapper {
  margin: 24px 0;
}
.svg-animate {
  display: inline-block;
  animation: pulse 3s ease-in-out infinite;
}
@keyframes pulse {
  0%,100% { transform: scale(1); }
  50%   { transform: scale(1.1); }
}

/* ─── Footer ─────────────────────────────────────────────────────────────── */
footer {
  background: #222;
  color: #bbb;
  text-align: center;
  padding: 20px 12px;
  font-size: 0.9rem;
}
footer a {
  color: #FFD700;
  text-decoration: none;
}

/* ─── Responsive ─────────────────────────────────────────────────────────── */
@media (max-width: 768px) {
  .header-content { flex-direction: column; }
  nav ul { flex-direction: column; margin-top: 12px; }
  nav li + li { margin-left: 0; margin-top: 8px; }
  .grid-container { grid-template-columns: 1fr; }
  .subject-name h1 { font-size: 2.2rem; }
}