:root {
  --bg: #f5f7fb;
  --surface: #ffffff;
  --surface-soft: #eef3fb;
  --text: #182235;
  --muted: #6e7a90;
  --line: #dfe5ef;
  --primary: #1f4b99;
  --primary-dark: #183a76;
  --primary-soft: #e9f0ff;
  --success: #217a4b;
  --success-soft: #e8f6ee;
  --warning: #a26200;
  --warning-soft: #fff3dd;
  --danger: #b33232;
  --danger-soft: #fdeaea;
  --shadow: 0 14px 40px rgba(33, 47, 74, 0.08);
  --radius: 22px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.5;
}

button, a { font: inherit; }
button { color: inherit; }
a { color: inherit; text-decoration: none; }

.app-shell {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 270px minmax(0, 1fr);
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  padding: 28px 20px;
  background: #102a56;
  color: white;
  display: flex;
  flex-direction: column;
  gap: 30px;
}

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

.brand-mark {
  width: 48px;
  height: 48px;
  border-radius: 16px;
  display: grid;
  place-items: center;
  background: white;
  color: var(--primary);
  font-weight: 900;
  letter-spacing: -0.04em;
}

.brand strong, .brand small { display: block; }
.brand small { margin-top: 2px; color: #bcd0f3; }

.nav-list { display: grid; gap: 8px; }

.nav-link {
  width: 100%;
  border: 0;
  background: transparent;
  color: #d8e5fb;
  border-radius: 14px;
  padding: 12px 14px;
  display: flex;
  align-items: center;
  gap: 12px;
  text-align: left;
  cursor: pointer;
}

.nav-link span { width: 20px; text-align: center; }
.nav-link:hover, .nav-link.active { background: rgba(255,255,255,.12); color: white; }

.sidebar-footer { margin-top: auto; display: grid; gap: 10px; }

.teacher-button, .secondary-button {
  border: 0;
  border-radius: 14px;
  padding: 12px 16px;
  font-weight: 800;
  cursor: pointer;
  text-align: center;
}

.teacher-button { background: white; color: var(--primary); }
.teacher-button:hover { background: #edf3ff; }
.secondary-button { background: rgba(255,255,255,.12); color: white; }

.main-content { min-width: 0; padding: 0 36px 48px; }

.topbar {
  min-height: 112px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--muted);
  font-size: .86rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
}

h1, h2, h3, p { margin-top: 0; }
h1 { margin-bottom: 0; font-size: clamp(1.7rem, 3vw, 2.35rem); letter-spacing: -.035em; }
h2 { letter-spacing: -.025em; }

.topbar-actions { display: flex; align-items: center; gap: 10px; }
.connection-status { color: var(--success); background: var(--success-soft); padding: 8px 11px; border-radius: 999px; font-size: .82rem; font-weight: 800; }
.connection-status.offline { color: var(--warning); background: var(--warning-soft); }
.teacher-button.compact { background: var(--primary); color: white; }

.content { max-width: 1260px; margin: 0 auto; }

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) minmax(280px, .75fr);
  gap: 20px;
  margin-bottom: 28px;
}

.hero-card, .panel, .item-card, .announcement-card, .loading-card, .empty-state {
  background: var(--surface);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}

.hero-card {
  min-height: 260px;
  padding: clamp(24px, 4vw, 38px);
  border-radius: 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  overflow: hidden;
  position: relative;
}

.hero-card::after {
  content: "";
  position: absolute;
  width: 240px;
  height: 240px;
  border-radius: 50%;
  background: var(--primary-soft);
  right: -80px;
  bottom: -100px;
}

.hero-card > * { position: relative; z-index: 1; }
.hero-label { color: var(--primary); font-size: .85rem; font-weight: 900; text-transform: uppercase; letter-spacing: .08em; }
.hero-card h2 { max-width: 700px; margin-bottom: 10px; font-size: clamp(1.7rem, 4vw, 2.8rem); line-height: 1.08; }
.hero-meta { display: flex; flex-wrap: wrap; gap: 10px; color: var(--muted); }

.countdown {
  margin-top: 26px;
  display: inline-flex;
  width: fit-content;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  border-radius: 999px;
  font-weight: 900;
}

.countdown.safe { background: var(--success-soft); color: var(--success); }
.countdown.soon { background: var(--warning-soft); color: var(--warning); }
.countdown.urgent, .countdown.overdue { background: var(--danger-soft); color: var(--danger); }

.quick-stats { display: grid; gap: 12px; }
.stat-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 20px;
  box-shadow: var(--shadow);
}
.stat-card strong { display: block; font-size: 2rem; letter-spacing: -.04em; }
.stat-card span { color: var(--muted); font-weight: 700; }

.section-header { display: flex; align-items: center; justify-content: space-between; gap: 20px; margin: 28px 0 14px; }
.section-header h2 { margin-bottom: 0; }
.text-button { border: 0; background: transparent; color: var(--primary); font-weight: 900; cursor: pointer; }

.card-grid { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: 16px; }

.item-card, .announcement-card { border-radius: var(--radius); padding: 22px; }
.item-card { display: flex; flex-direction: column; gap: 14px; }

.card-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 14px; }
.item-card h3, .announcement-card h3 { margin-bottom: 5px; font-size: 1.15rem; }
.card-subtitle, .muted { color: var(--muted); }

.badge {
  display: inline-flex;
  align-items: center;
  border-radius: 999px;
  padding: 6px 10px;
  font-size: .76rem;
  font-weight: 900;
  white-space: nowrap;
}
.badge.assignment { background: #e8f0ff; color: #2556a8; }
.badge.project { background: #eee8ff; color: #6941b4; }
.badge.exam { background: #ffe9e9; color: #aa3333; }
.badge.completed { background: var(--success-soft); color: var(--success); }

.card-details { color: #42506a; }
.card-footer { margin-top: auto; padding-top: 4px; display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.due-date { font-size: .88rem; color: var(--muted); font-weight: 700; }

.progress-track { height: 7px; overflow: hidden; background: #edf0f4; border-radius: 99px; }
.progress-bar { height: 100%; background: var(--primary); border-radius: inherit; }

.panel { border-radius: var(--radius); padding: 24px; }

.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 18px;
}
.filter-button {
  border: 1px solid var(--line);
  background: var(--surface);
  padding: 9px 13px;
  border-radius: 999px;
  font-weight: 800;
  cursor: pointer;
}
.filter-button.active, .filter-button:hover { border-color: var(--primary); background: var(--primary-soft); color: var(--primary); }

.announcement-list { display: grid; gap: 14px; }
.announcement-card { display: grid; grid-template-columns: auto minmax(0,1fr); gap: 16px; }
.announcement-date { width: 62px; text-align: center; border-radius: 16px; background: var(--primary-soft); color: var(--primary); padding: 10px 8px; font-weight: 900; }
.announcement-date strong, .announcement-date span { display: block; }
.announcement-date strong { font-size: 1.35rem; line-height: 1; }
.announcement-date span { margin-top: 4px; font-size: .72rem; text-transform: uppercase; }

.resource-list { display: flex; flex-wrap: wrap; gap: 8px; }
.resource-link { display: inline-flex; padding: 8px 11px; border-radius: 10px; background: var(--surface-soft); color: var(--primary); font-size: .86rem; font-weight: 800; }

.loading-card, .empty-state { border-radius: var(--radius); padding: 44px 24px; text-align: center; color: var(--muted); }
.empty-icon { width: 58px; height: 58px; margin: 0 auto 14px; border-radius: 50%; display: grid; place-items: center; background: var(--success-soft); color: var(--success); font-size: 1.5rem; font-weight: 900; }

.mobile-nav { display: none; }

@media (max-width: 980px) {
  .app-shell { grid-template-columns: 220px minmax(0,1fr); }
  .sidebar { padding: 24px 14px; }
  .main-content { padding: 0 22px 36px; }
  .hero-grid { grid-template-columns: 1fr; }
  .quick-stats { grid-template-columns: repeat(3,1fr); }
}

@media (max-width: 720px) {
  body { padding-bottom: calc(76px + env(safe-area-inset-bottom)); }
  .app-shell { display: block; }
  .sidebar { display: none; }
  .main-content { padding: 0 16px 28px; }
  .topbar { min-height: 92px; }
  .topbar-actions .teacher-button { display: none; }
  .connection-status { font-size: .72rem; }
  .hero-card { min-height: 230px; }
  .quick-stats { grid-template-columns: repeat(3, 1fr); gap: 8px; }
  .stat-card { padding: 15px 12px; }
  .stat-card strong { font-size: 1.45rem; }
  .stat-card span { font-size: .75rem; }
  .card-grid { grid-template-columns: 1fr; }
  .announcement-card { grid-template-columns: 54px minmax(0,1fr); padding: 18px; }
  .announcement-date { width: 54px; }
  .mobile-nav {
    position: fixed;
    display: grid;
    grid-template-columns: repeat(4,1fr);
    left: 10px;
    right: 10px;
    bottom: calc(10px + env(safe-area-inset-bottom));
    z-index: 20;
    background: rgba(255,255,255,.96);
    border: 1px solid var(--line);
    border-radius: 22px;
    box-shadow: 0 15px 45px rgba(30,46,75,.18);
    overflow: hidden;
  }
  .mobile-nav-link {
    border: 0;
    background: transparent;
    min-height: 62px;
    display: grid;
    place-items: center;
    align-content: center;
    gap: 2px;
    color: var(--muted);
  }
  .mobile-nav-link span { font-size: 1.1rem; }
  .mobile-nav-link small { font-size: .67rem; font-weight: 800; }
  .mobile-nav-link.active { color: var(--primary); background: var(--primary-soft); }
}

@media (max-width: 420px) {
  .main-content { padding-inline: 12px; }
  .hero-card, .panel, .item-card { border-radius: 19px; }
  .hero-meta { display: grid; gap: 5px; }
  .card-footer { align-items: flex-start; flex-direction: column; }
}