:root {
  --brand: #0a6e8f;
  --brand-dark: #055a75;
  --brand-light: #e8f4f8;
  --accent: #14b8a6;
  --text: #1e293b;
  --muted: #64748b;
  --bg: #f4f7fa;
  --card: #ffffff;
  --border: #e2e8f0;
  --danger: #dc2626;
  --shadow: 0 10px 40px rgba(15, 23, 42, 0.08);
  --radius: 14px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
}

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

img {
  max-width: 100%;
  display: block;
}

.container {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
}

.site-header {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 20;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 72px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  font-size: 1.05rem;
}

.logo-mark {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--brand), var(--accent));
  color: #fff;
  display: grid;
  place-items: center;
  font-size: 1.1rem;
  font-weight: 800;
}

.nav {
  display: flex;
  align-items: center;
  gap: 18px;
  flex-wrap: wrap;
}

.nav a {
  color: var(--muted);
  font-size: 0.95rem;
}

.nav a:hover,
.nav a.active {
  color: var(--brand);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: none;
  border-radius: 999px;
  padding: 12px 22px;
  font: inherit;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: var(--brand);
  color: #fff;
  box-shadow: 0 8px 24px rgba(10, 110, 143, 0.25);
}

.btn-primary:hover {
  background: var(--brand-dark);
}

.btn-secondary {
  background: #fff;
  color: var(--brand);
  border: 1px solid var(--border);
}

.hero {
  padding: 72px 0 56px;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 32px;
  align-items: center;
}

.hero-card,
.panel,
.course-card,
.stat-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.hero-card {
  padding: 28px;
}

.hero h1 {
  font-size: clamp(2rem, 4vw, 3rem);
  line-height: 1.15;
  margin: 0 0 16px;
}

.lead {
  color: var(--muted);
  font-size: 1.08rem;
  margin: 0 0 24px;
}

.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.hero-visual {
  min-height: 320px;
  padding: 28px;
  background:
    radial-gradient(circle at top right, rgba(20, 184, 166, 0.18), transparent 40%),
    linear-gradient(160deg, #ffffff, #eef7fb);
  display: grid;
  gap: 16px;
}

.hero-visual h3 {
  margin: 0;
}

.feature-list {
  display: grid;
  gap: 12px;
}

.feature-item {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 14px 16px;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.75);
  border: 1px solid var(--border);
}

.feature-dot {
  width: 10px;
  height: 10px;
  margin-top: 7px;
  border-radius: 50%;
  background: var(--accent);
  flex-shrink: 0;
}

.section {
  padding: 56px 0;
}

.section-title {
  margin: 0 0 10px;
  font-size: 1.8rem;
}

.section-subtitle {
  margin: 0 0 28px;
  color: var(--muted);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px;
}

.course-card {
  padding: 22px;
}

.course-card h3 {
  margin: 0 0 8px;
}

.course-meta {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin: 14px 0 18px;
}

.tag {
  display: inline-flex;
  align-items: center;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--brand-light);
  color: var(--brand-dark);
  font-size: 0.82rem;
  font-weight: 600;
}

.site-footer {
  margin-top: 48px;
  padding: 28px 0 40px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.92rem;
}

.footer-grid {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

.login-page {
  min-height: calc(100vh - 72px);
  display: grid;
  place-items: center;
  padding: 40px 16px;
}

.login-card {
  width: min(440px, 100%);
  padding: 32px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.login-card h1 {
  margin: 0 0 8px;
  font-size: 1.6rem;
}

.login-card p {
  margin: 0 0 24px;
  color: var(--muted);
}

.field {
  display: grid;
  gap: 8px;
  margin-bottom: 16px;
}

.field label {
  font-size: 0.92rem;
  font-weight: 600;
}

.field input {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px 14px;
  font: inherit;
}

.field input:focus {
  outline: 2px solid rgba(10, 110, 143, 0.18);
  border-color: var(--brand);
}

.error-box {
  display: none;
  margin-bottom: 16px;
  padding: 12px 14px;
  border-radius: 12px;
  background: #fef2f2;
  color: var(--danger);
  border: 1px solid #fecaca;
  font-size: 0.92rem;
}

.error-box.visible {
  display: block;
}

.portal-layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 24px;
  padding: 28px 0 48px;
}

.sidebar {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  height: fit-content;
  position: sticky;
  top: 92px;
}

.sidebar h2 {
  margin: 0 0 6px;
  font-size: 1rem;
}

.sidebar .user-meta {
  color: var(--muted);
  font-size: 0.88rem;
  margin-bottom: 18px;
}

.sidebar nav {
  display: grid;
  gap: 8px;
}

.sidebar nav a {
  padding: 10px 12px;
  border-radius: 10px;
  color: var(--text);
}

.sidebar nav a:hover,
.sidebar nav a.active {
  background: var(--brand-light);
  color: var(--brand-dark);
}

.panel {
  padding: 24px;
}

.progress-bar {
  height: 10px;
  background: #e2e8f0;
  border-radius: 999px;
  overflow: hidden;
  margin-top: 8px;
}

.progress-bar span {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--brand), var(--accent));
}

.stats-row {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}

.stat-card {
  padding: 18px;
}

.stat-card strong {
  display: block;
  font-size: 1.6rem;
  margin-bottom: 4px;
}

.lesson-list {
  display: grid;
  gap: 12px;
}

.lesson-item {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: #fff;
}

.lesson-item.done {
  border-color: #bbf7d0;
  background: #f0fdf4;
}

.muted {
  color: var(--muted);
}

@media (max-width: 900px) {
  .hero-grid,
  .grid-3,
  .grid-2,
  .portal-layout,
  .stats-row {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
  }

  .nav .hide-mobile {
    display: none;
  }
}