:root {
  --color-primary: #2563EB;
  --color-primary-dark: #1D4ED8;
  --color-success: #10B981;
  --color-warning: #F59E0B;
  --color-danger: #BE3A34;
  --color-text: #111827;
  --color-text-muted: #607370;
  --color-border: #E5E7EB;
  --color-bg: #F9FAFB;
  --color-card-bg: #FFFFFF;
  --radius: 10px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--font);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.5;
}

.app-header {
  background: var(--color-card-bg);
  border-bottom: 1px solid var(--color-border);
  padding: 14px 24px;
}
.header-container { display: flex; align-items: center; justify-content: space-between; max-width: 1100px; margin: 0 auto; }
.brand-link { display: flex; align-items: center; gap: 8px; text-decoration: none; color: var(--color-text); font-weight: 700; font-size: 18px; }
.header-nav { display: flex; gap: 20px; }
.nav-link { color: var(--color-text-muted); text-decoration: none; font-size: 14px; font-weight: 500; }
.nav-link:hover, .nav-link.active { color: var(--color-primary); }

.app-layout { display: flex; max-width: 1100px; margin: 0 auto; gap: 24px; padding: 24px; }
.app-sidebar { width: 220px; flex-shrink: 0; }
.nav-section { margin-bottom: 20px; }
.nav-section-title { font-size: 12px; text-transform: uppercase; color: var(--color-text-muted); margin-bottom: 8px; }
.nav-list { list-style: none; padding: 0; margin: 0; }
.nav-item a { display: block; padding: 6px 10px; border-radius: 6px; color: var(--color-text); text-decoration: none; font-size: 14px; }
.nav-item a:hover, .nav-item a.active { background: #EFF6FF; color: var(--color-primary); }

.app-main { flex: 1; min-width: 0; }

.app-footer { border-top: 1px solid var(--color-border); padding: 20px 24px; margin-top: 40px; }
.footer-container { max-width: 1100px; margin: 0 auto; display: flex; justify-content: space-between; align-items: center; font-size: 13px; color: var(--color-text-muted); }
.footer-nav a { color: var(--color-text-muted); margin-left: 16px; text-decoration: none; }

.card { background: var(--color-card-bg); border: 1px solid var(--color-border); border-radius: var(--radius); padding: 20px; margin-bottom: 16px; }
.card-title { font-size: 16px; font-weight: 600; margin: 0 0 12px; }

.btn { display: inline-flex; align-items: center; gap: 6px; padding: 10px 18px; border-radius: 8px; border: none; font-size: 14px; font-weight: 600; cursor: pointer; }
.btn-primary { background: var(--color-primary); color: #fff; }
.btn-primary:hover { background: var(--color-primary-dark); }
.btn-secondary { background: #fff; border: 1px solid var(--color-border); color: var(--color-text); }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

input, textarea, select {
  width: 100%; padding: 10px 12px; border: 1px solid var(--color-border);
  border-radius: 8px; font-size: 14px; font-family: var(--font); margin-bottom: 12px;
}
label { display: block; font-size: 13px; font-weight: 600; margin-bottom: 6px; }

[data-error-region] { background: #FEF2F2; color: var(--color-danger); padding: 10px 14px; border-radius: 8px; margin-bottom: 12px; font-size: 14px; }
[data-success-region] { background: #ECFDF5; color: var(--color-success); padding: 10px 14px; border-radius: 8px; margin-bottom: 12px; font-size: 14px; }

.badge { display: inline-block; padding: 3px 10px; border-radius: 999px; font-size: 12px; font-weight: 600; }
.badge-jargon { background: #FEF3C7; color: #92400E; }
.badge-minor { background: #D1FAE5; color: #065F46; }
.badge-moderate { background: #FEF3C7; color: #92400E; }
.badge-major { background: #FEE2E2; color: #991B1B; }

.chat-window { display: flex; flex-direction: column; gap: 12px; max-height: 480px; overflow-y: auto; padding: 16px; border: 1px solid var(--color-border); border-radius: var(--radius); background: #fff; margin-bottom: 12px; }
.chat-message { max-width: 75%; padding: 10px 14px; border-radius: 12px; font-size: 14px; }
.chat-message.role-student { align-self: flex-end; background: var(--color-primary); color: #fff; }
.chat-message.role-ai { align-self: flex-start; background: #F3F4F6; color: var(--color-text); }

.input-row { display: flex; gap: 8px; }
.input-row input { margin-bottom: 0; flex: 1; }

.empty-state { text-align: center; padding: 40px 20px; color: var(--color-text-muted); }
[hidden] { display: none !important; }