* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; min-height: 100%; }
html { background: #fff; }
body {
  color: var(--color-navy-700);
  font-family: var(--font-body);
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}
h1, h2, h3, h4 { color: var(--color-navy-900); margin: 0; }
h1, h2, h3 { font-family: var(--font-heading); line-height: 1.02; }
p { margin: 0; }
a { color: inherit; text-decoration: none; }
button, input { font: inherit; }
button { cursor: pointer; }
img, svg { display: block; max-width: 100%; }
.container { margin: 0 auto; max-width: 1240px; padding: 0 32px; width: 100%; }

.site-header {
  align-items: center;
  background: rgba(255,255,255,.97);
  border-bottom: 1px solid #dce2e9;
  box-shadow: 0 7px 18px rgba(7,17,47,.08);
  display: flex;
  height: 88px;
  justify-content: space-between;
  padding: 0 40px 0 32px;
  position: relative;
  z-index: 20;
}
.brand { align-items: center; color: var(--color-navy-950); display: flex; font-size: 1.72rem; font-weight: 700; gap: 18px; letter-spacing: -.035em; }
.brand-mark { align-items: center; background: linear-gradient(145deg,#ff6723,#ff3500); border-radius: 9px; box-shadow: 0 7px 14px rgba(255,75,10,.28); color: #fff; display: flex; flex: 0 0 auto; height: 56px; justify-content: center; width: 51px; }
.brand-mark svg { height: 40px; width: 33px; }
.header-actions { align-items: center; display: flex; gap: 30px; }
.header-user-info {
  color: var(--color-navy-900);
  font-size: .92rem;
  font-weight: 600;
  max-width: 200px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.header-icon-btn { align-items: center; display: flex; height: 34px; justify-content: center; width: 34px; }
.header-icon-btn svg { height: 23px; width: 23px; }

.lesson-page { background-color: #f4fbff; background-image: radial-gradient(circle at 48% 15%,rgba(255,255,255,.92),transparent 35%), repeating-radial-gradient(ellipse at 77% 7%, transparent 0 24px, rgba(71,155,194,.045) 25px 26px); min-height: 100vh; }
.lesson-page main { min-height: calc(100vh - 68px); }
.lesson-page::after { background-image: linear-gradient(rgba(32,145,201,.11) 1px,transparent 1px),linear-gradient(90deg,rgba(32,145,201,.11) 1px,transparent 1px); content:""; height: 220px; opacity: .35; pointer-events: none; position: fixed; right: -80px; top: 80px; transform: rotate(15deg); width: 260px; z-index: -1; }

@media (max-width: 720px) {
  .container { padding: 0 18px; }
  .site-header { height: 70px; padding: 0 16px; }
  .brand { font-size: 1.15rem; gap: 10px; }
  .brand-mark { border-radius: 7px; height: 43px; width: 40px; }
  .brand-mark svg { height: 31px; }
  .header-actions { gap: 10px; }
  .header-user-info { font-size: .82rem; max-width: 110px; }
  .header-icon-btn { display: none; }
}