:root {
  --bg-main: #f4f6f8;
  --bg-surface: #ffffff;
  --bg-soft: #eef3f8;

  --text-main: #172033;
  --text-secondary: #566176;
  --text-light: #ffffff;

  --blue: #2563eb;
  --blue-dark: #173b8f;
  --blue-soft: #dbeafe;

  --pink: #ec4899;
  --pink-soft: #fce7f3;

  --green: #16a34a;
  --green-soft: #dcfce7;

  --purple: #7c3aed;
  --purple-soft: #ede9fe;

  --border: #dfe5ec;
  --shadow: 0 14px 40px rgba(23, 32, 51, 0.08);

  --radius-small: 10px;
  --radius-medium: 18px;
  --radius-large: 28px;

  --container: 1180px;
  --transition: 0.25s ease;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg-main);
  color: var(--text-main);
  font-family:
    Inter,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    Roboto,
    Arial,
    sans-serif;
  line-height: 1.7;
}

img {
  display: block;
  width: 100%;
  height: auto;
}

a {
  color: inherit;
  text-decoration: none;
}

button,
input,
textarea,
select {
  font: inherit;
}

.container {
  width: min(92%, var(--container));
  margin-inline: auto;
}

/* Header */

.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.94);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(14px);
}

.header-inner {
  min-height: 76px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.site-logo {
  color: var(--blue-dark);
  font-size: 1.45rem;
  font-weight: 800;
  letter-spacing: -0.04em;
}

.main-nav {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 8px;
}

.main-nav a {
  padding: 9px 12px;
  border-radius: var(--radius-small);
  color: var(--text-secondary);
  font-size: 0.94rem;
  font-weight: 650;
  transition:
    background var(--transition),
    color var(--transition);
}

.main-nav a:hover,
.main-nav a[aria-current="page"] {
  background: var(--blue-soft);
  color: var(--blue-dark);
}

.menu-toggle {
  display: none;
  border: 1px solid var(--border);
  background: var(--bg-surface);
  color: var(--text-main);
  padding: 8px 11px;
  border-radius: var(--radius-small);
  cursor: pointer;
}

/* Hero */

.hero-section {
  padding: 110px 0 100px;
  background:
    radial-gradient(
      circle at 15% 20%,
      rgba(37, 99, 235, 0.16),
      transparent 32%
    ),
    radial-gradient(
      circle at 85% 25%,
      rgba(236, 72, 153, 0.14),
      transparent 30%
    ),
    radial-gradient(
      circle at 55% 90%,
      rgba(22, 163, 74, 0.12),
      transparent 30%
    ),
    var(--bg-surface);
  border-bottom: 1px solid var(--border);
}

.hero-content {
  max-width: 920px;
}

.eyebrow {
  display: inline-block;
  margin-bottom: 14px;
  color: var(--blue);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.hero-section h1 {
  max-width: 900px;
  margin: 0;
  font-size: clamp(2.4rem, 6vw, 5.1rem);
  line-height: 1.03;
  letter-spacing: -0.055em;
}

.hero-section p {
  max-width: 760px;
  margin: 26px 0 0;
  color: var(--text-secondary);
  font-size: 1.15rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 34px;
}

/* Buttons */

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 12px 20px;
  border: 1px solid var(--blue);
  border-radius: 999px;
  background: var(--blue);
  color: var(--text-light);
  font-weight: 750;
  transition:
    transform var(--transition),
    box-shadow var(--transition),
    background var(--transition);
}

.button:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 24px rgba(37, 99, 235, 0.2);
}

.button-secondary {
  background: transparent;
  color: var(--blue-dark);
}

.button-secondary:hover {
  background: var(--blue-soft);
}

/* Sections */

.section {
  padding: 88px 0;
}

.section-heading {
  max-width: 780px;
  margin-bottom: 42px;
}

.section-heading h2 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3.25rem);
  line-height: 1.12;
  letter-spacing: -0.04em;
}

.section-heading p {
  margin: 18px 0 0;
  color: var(--text-secondary);
  font-size: 1.03rem;
}

/* Categories */

.category-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.category-card {
  min-height: 310px;
  display: flex;
  flex-direction: column;
  padding: 28px;
  border: 1px solid var(--border);
  border-radius: var(--radius-large);
  background: var(--bg-surface);
  box-shadow: var(--shadow);
  transition:
    transform var(--transition),
    box-shadow var(--transition);
}

.category-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 20px 48px rgba(23, 32, 51, 0.13);
}

.category-blue {
  background: linear-gradient(145deg, #ffffff, var(--blue-soft));
}

.category-pink {
  background: linear-gradient(145deg, #ffffff, var(--pink-soft));
}

.category-green {
  background: linear-gradient(145deg, #ffffff, var(--green-soft));
}

.category-purple {
  background: linear-gradient(145deg, #ffffff, var(--purple-soft));
}

.card-number {
  color: var(--text-secondary);
  font-size: 0.8rem;
  font-weight: 800;
}

.category-card h3 {
  margin: 52px 0 12px;
  font-size: 1.5rem;
  line-height: 1.2;
}

.category-card p {
  margin: 0;
  color: var(--text-secondary);
}

.card-link {
  margin-top: auto;
  padding-top: 24px;
  color: var(--blue-dark);
  font-weight: 750;
}

/* Articles */

.featured-section {
  background: var(--bg-soft);
}

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

.article-card {
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: var(--radius-medium);
  background: var(--bg-surface);
  box-shadow: var(--shadow);
}

.article-image {
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: var(--bg-soft);
}

.article-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s ease;
}

.article-card:hover .article-image img {
  transform: scale(1.04);
}

.article-content {
  padding: 24px;
}

.article-category {
  color: var(--blue);
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.article-content h3 {
  margin: 12px 0;
  font-size: 1.3rem;
  line-height: 1.3;
}

.article-content p {
  margin: 0 0 18px;
  color: var(--text-secondary);
}

.article-content a,
.text-link {
  color: var(--blue-dark);
  font-weight: 750;
}

.article-content a:hover,
.text-link:hover {
  text-decoration: underline;
}

/* Student banner */

.student-section {
  background: var(--bg-surface);
}

.student-banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 40px;
  padding: 54px;
  border: 1px solid var(--border);
  border-radius: var(--radius-large);
  background:
    linear-gradient(
      120deg,
      rgba(22, 163, 74, 0.12),
      rgba(37, 99, 235, 0.1),
      rgba(236, 72, 153, 0.1)
    );
  box-shadow: var(--shadow);
}

.student-banner h2 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3.1rem);
  line-height: 1.1;
}

.student-banner p {
  max-width: 720px;
  margin: 16px 0 0;
  color: var(--text-secondary);
}

/* Footer */

.site-footer {
  margin-top: 40px;
  padding-top: 70px;
  background: #172033;
  color: #e8edf5;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.7fr 1fr 1fr 1fr;
  gap: 44px;
}

.footer-logo {
  color: #ffffff;
}

.footer-brand p {
  max-width: 360px;
  color: #aeb8c8;
}

.site-footer h3 {
  margin: 0 0 18px;
  color: #ffffff;
  font-size: 1rem;
}

.site-footer a {
  display: block;
  margin: 8px 0;
  color: #c4ccda;
  transition: color var(--transition);
}

.site-footer a:hover {
  color: #ffffff;
}

.footer-contact {
  display: flex;
  flex-wrap: wrap;
  gap: 28px;
  margin-top: 48px;
  padding: 24px 0;
  border-top: 1px solid rgba(255, 255, 255, 0.12);
}

.footer-contact p {
  margin: 0;
  color: #aeb8c8;
}

.footer-contact a {
  display: inline;
  color: #ffffff;
}

.footer-bottom {
  padding: 22px 0 30px;
  border-top: 1px solid rgba(255, 255, 255, 0.12);
}

.footer-bottom p {
  margin: 0;
  color: #8f9bad;
  font-size: 0.9rem;
}

/* Responsive */

@media (max-width: 1050px) {
  .category-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .article-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 800px) {
  .header-inner {
    min-height: 68px;
  }

  .menu-toggle {
    display: block;
  }

  .main-nav {
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    padding: 14px 4%;
    border-bottom: 1px solid var(--border);
    background: rgba(255, 255, 255, 0.98);
  }

  .main-nav.is-open {
    display: flex;
  }

  .main-nav a {
    width: 100%;
    padding: 13px;
  }

  .hero-section {
    padding: 82px 0 76px;
  }

  .student-banner {
    align-items: flex-start;
    flex-direction: column;
    padding: 36px;
  }
}

@media (max-width: 620px) {
  .section {
    padding: 68px 0;
  }

  .category-grid,
  .article-grid,
  .footer-grid {
    grid-template-columns: 1fr;
  }

  .category-card {
    min-height: 270px;
  }

  .hero-section h1 {
    font-size: clamp(2.2rem, 12vw, 3.5rem);
  }

  .hero-section p {
    font-size: 1rem;
  }

  .hero-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .button {
    width: 100%;
  }

  .footer-contact {
    flex-direction: column;
    gap: 8px;
  }
}