:root {
  --choc-900: #3a1b0c;
  --choc-800: #4b240f;
  --choc-700: #5a2e15;
  --choc-600: #6d3a1b;

  --pb-100: #fff2d8;
  --pb-200: #f6deb2;
  --pb-300: #eed099;
  --pb-400: #e4c07d;

  --orange: #ff7a00;
  --orange-dark: #e56600;
  --yellow: #ffd23f;

  --shadow-soft: 0 6px 18px rgba(58,27,12,.18);
  --shadow-deep: 0 18px 42px rgba(58,27,12,.35);
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  margin: 0;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  color: var(--choc-900);
  background:
    linear-gradient(180deg, var(--pb-200), var(--pb-300));
}

.wrapper {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main { flex: 1; }

.container {
  width: 90%;
  max-width: 1100px;
  margin: 0 auto;
}

a {
  text-decoration: none;
  color: inherit;
  transition: color .25s ease;
}

a:hover { color: var(--orange); }

.site-header {
  background: linear-gradient(180deg, var(--pb-100), var(--pb-300));
  border-bottom: 8px solid var(--choc-700);
}

.header-top {
  display: flex;
  justify-content: center;
  padding: 18px 0 14px;
}

.logo {
  width: 220px;
  filter: drop-shadow(0 4px 6px rgba(0,0,0,.35));
}

.main-nav {
  background: linear-gradient(180deg, var(--choc-700), var(--choc-900));
}

.nav-links {
  list-style: none;
  display: flex;
  justify-content: center;
  gap: 36px;
  padding: 14px 0;
}

.nav-links a {
  font-weight: 900;
  letter-spacing: .3px;
  color: var(--yellow);
  position: relative;
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -8px;
  width: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--orange), var(--yellow));
  transition: width .25s ease;
}

.nav-links a:hover::after {
  width: 100%;
}

.site-footer {
  background: linear-gradient(180deg, var(--choc-900), #2a1409);
  color: var(--yellow);
  text-align: center;
  padding: 18px 0;
  font-size: 14px;
}

.section-title {
  font-size: 22px;
  font-weight: 900;
  text-align: center;
  margin: 22px 0;
  color: var(--choc-800);
}

.featured-article {
  padding: 46px 22px;
  text-align: center;
  background:
    linear-gradient(180deg, var(--pb-300), var(--pb-200));
  border-top: 10px solid var(--choc-700);
}

.featured-image {
  max-width: 100%;
  border-radius: 14px;
  border: 6px solid var(--choc-600);
  box-shadow: var(--shadow-soft);
  transition: transform .35s ease;
}

.featured-image:hover {
  transform: scale(1.035);
}

.article-title {
  margin-top: 24px;
  font-size: 24px;
  font-weight: 900;
}

.content-grid {
  display: grid;
  gap: 40px;
  padding: 44px 0;
  grid-template-columns: 2.5fr 2fr 1.5fr;
}

.new-articles,
.featured-quizzes {
  background: linear-gradient(180deg, var(--pb-200), var(--pb-300));
}

.article-grid,
.block-grid {
  display: grid;
  gap: 20px;
}

.article-grid {
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.homepage {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 26px;
  padding: 24px 0;
}

.block {
  background:
    linear-gradient(180deg, var(--pb-300), var(--pb-200));
  border-radius: 18px;
  padding: 16px;
  border: 5px solid var(--choc-700);
  box-shadow: var(--shadow-soft);
}

.block-card {
  background:
    linear-gradient(180deg, var(--pb-100), var(--pb-200));
  border-radius: 14px;
  overflow: hidden;
  border: 3px solid var(--choc-600);
  transition: transform .25s ease, box-shadow .25s ease;
}

.block-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-deep);
}

.block-card img {
  width: 100%;
  height: 120px;
  object-fit: cover;
  border-bottom: 4px solid var(--choc-600);
}

.block-card h3 {
  padding: 10px;
  font-size: 14px;
  font-weight: 800;
}

.grade-calculator {
  max-width: 520px;
  margin: 48px auto;
  padding: 34px;
  background: linear-gradient(180deg, var(--pb-200), var(--pb-300));
  border-radius: 18px;
  border: 5px solid var(--choc-700);
  box-shadow: var(--shadow-soft);
  text-align: center;
}

.assignment {
  background: linear-gradient(180deg, var(--pb-100), var(--pb-200));
  border-radius: 10px;
  border: 2px solid var(--choc-600);
  padding: 16px;
}

button {
  background: linear-gradient(180deg, var(--orange), var(--orange-dark));
  border: none;
  border-radius: 8px;
  color: var(--choc-900);
  font-weight: 900;
  padding: 12px 22px;
  box-shadow: var(--shadow-soft);
  cursor: pointer;
}

button:hover { filter: brightness(1.08); }

#sus-bot-button {
  position: fixed;
  bottom: 20px;
  right: 20px;
  background: linear-gradient(180deg, var(--choc-700), var(--choc-900));
  color: var(--yellow);
  font-size: 26px;
  padding: 14px 16px;
  border-radius: 50%;
  box-shadow: var(--shadow-deep);
}

#sus-bot {
  position: fixed;
  bottom: 90px;
  right: 20px;
  width: 300px;
  background: linear-gradient(180deg, var(--pb-200), var(--pb-300));
  border-radius: 20px;
  border: 5px solid var(--choc-700);
  box-shadow: var(--shadow-deep);
  overflow: hidden;
}

.sus-header {
  background: linear-gradient(180deg, var(--choc-800), var(--choc-900));
  color: var(--yellow);
  padding: 12px;
  font-weight: 900;
  text-align: center;
}

#sus-messages {
  padding: 14px;
  height: 240px;
  overflow-y: auto;
}

.sus-message {
  display: flex;
  margin-bottom: 12px;
}

.sus-bubble {
  padding: 10px 12px;
  border-radius: 14px;
  max-width: 85%;
}

.bot .sus-bubble {
  background: linear-gradient(180deg, var(--yellow), #ffeb82);
  color: var(--choc-900);
}

.user {
  justify-content: flex-end;
}

.user .sus-bubble {
  background: linear-gradient(180deg, var(--pb-100), var(--pb-200));
  border: 2px solid var(--choc-600);
}

.sus-input {
  display: flex;
  border-top: 4px solid var(--choc-700);
}

.sus-input input {
  flex: 1;
  background: linear-gradient(180deg, #fff4dc, var(--pb-200));
  border: none;
  padding: 10px;
  outline: none;
}

.sus-input button {
  border-radius: 0;
}

@media (max-width: 1200px) {
  .homepage { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 1024px) {
  .content-grid { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  .homepage { grid-template-columns: 1fr; }
}