:root {
  color-scheme: dark;
  font-family: Inter, ui-sans-serif, system-ui, sans-serif;
  color: #e8f3ee;
  background: #07130f;
  font-synthesis: none;
}

* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; background: radial-gradient(circle at 80% 0, #16372d 0, #07130f 36rem); }
a { color: #80e0b9; text-decoration: none; }
button, input, select, textarea { font: inherit; }
.skip-link { position: fixed; z-index: 10; top: .5rem; left: .5rem; padding: .65rem 1rem; color: #062116; background: #6ee7b7; border-radius: .5rem; transform: translateY(-150%); }
.skip-link:focus { transform: translateY(0); }
.app-shell { display: grid; grid-template-columns: 16rem 1fr; min-height: 100vh; }
.sidebar { position: sticky; top: 0; height: 100vh; padding: 2rem 1.4rem; border-right: 1px solid #25453a; background: rgb(7 19 15 / .88); }
.brand { display: block; color: #fff; font-size: 1.3rem; font-weight: 800; letter-spacing: -.03em; }
.brand-note { margin: .3rem 0 2rem; color: #88a99b; font-size: .8rem; }
nav { display: grid; gap: .45rem; }
nav a { padding: .7rem .8rem; color: #c5d8d0; border-radius: .6rem; }
nav a:hover { color: #fff; background: #18372c; }
nav a[aria-current="page"] { color: #fff; background: #18372c; box-shadow: inset 3px 0 #6ee7b7; }
.auth-badge { position: absolute; display: grid; gap: .45rem; bottom: 1.5rem; left: 1.4rem; right: 1.4rem; padding: .7rem; color: #a9c4b9; border: 1px solid #25453a; border-radius: .6rem; font-size: .8rem; }
.link-button { width: fit-content; padding: 0; color: #80e0b9; background: transparent; border: 0; cursor: pointer; text-decoration: underline; }
.link-button:disabled { opacity: .6; cursor: wait; }
.content { width: min(68rem, 100%); margin: 0 auto; padding: 4rem 3rem; }
.hero { max-width: 52rem; padding: 4rem 0; }
.hero h1, .page-header h1 { margin: .4rem 0 1rem; color: #fff; font-size: clamp(2.2rem, 5vw, 4rem); line-height: 1.03; letter-spacing: -.045em; }
.hero p, .page-header p { max-width: 45rem; color: #a9c4b9; font-size: 1.08rem; line-height: 1.65; }
.eyebrow { color: #62d2a3; font-size: .75rem; font-weight: 800; letter-spacing: .12em; text-transform: uppercase; }
.actions { display: flex; flex-wrap: wrap; gap: .7rem; margin-top: 1.7rem; }
.button { display: inline-flex; justify-content: center; padding: .75rem 1rem; color: #dcebe5; background: #172a23; border: 1px solid #36584b; border-radius: .65rem; cursor: pointer; }
.button.primary { color: #062116; background: #6ee7b7; border-color: #6ee7b7; font-weight: 750; }
.button:disabled { opacity: .55; cursor: wait; }
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; }
.cards article, .panel, .chat-panel { padding: 1.4rem; background: rgb(15 34 27 / .85); border: 1px solid #29483c; border-radius: 1rem; box-shadow: 0 1.2rem 3rem rgb(0 0 0 / .14); }
.cards h2 { margin-top: 0; color: #fff; font-size: 1.05rem; }
.cards p, .panel p { color: #9db8ad; line-height: 1.6; }
.page-header { margin-bottom: 2rem; }
.page-header h1 { font-size: clamp(2rem, 4vw, 3rem); }
.chat-panel { padding: 0; overflow: hidden; }
.transcript { min-height: 25rem; max-height: 58vh; padding: 1.4rem; overflow-y: auto; }
.empty-state { margin: 6rem auto; max-width: 32rem; color: #9db8ad; text-align: center; }
.empty-state h2 { color: #fff; }
.message { max-width: 75%; margin: .7rem 0; padding: .8rem 1rem; border-radius: .8rem; }
.message strong { font-size: .72rem; color: #7dd3b0; text-transform: uppercase; }
.message p { margin: .3rem 0 0; white-space: pre-wrap; line-height: 1.55; }
.message.learner { margin-left: auto; background: #285642; }
.message.tutor { background: #172a23; }
.message.system { border: 1px solid #754646; background: #392323; }
.composer { display: flex; gap: .7rem; padding: 1rem; border-top: 1px solid #29483c; }
.composer textarea { flex: 1; min-height: 4.5rem; resize: vertical; }
input, select, textarea { width: 100%; margin-top: .45rem; padding: .75rem; color: #eef8f4; background: #091b15; border: 1px solid #36584b; border-radius: .55rem; outline: none; }
input:focus, select:focus, textarea:focus { border-color: #6ee7b7; box-shadow: 0 0 0 3px rgb(110 231 183 / .12); }
label { color: #c8ddd4; font-size: .9rem; font-weight: 650; }
.stack { display: grid; gap: 1.2rem; max-width: 38rem; }
.check { display: flex; gap: .7rem; align-items: center; }
.check input { width: auto; margin: 0; }
.login-page { display: grid; place-items: center; min-height: 100vh; padding: 1.5rem; }
.login-card { display: grid; gap: 1.1rem; width: min(27rem, 100%); padding: 2rem; }
.login-card h1 { margin: .6rem 0 0; }
.login-card p { margin: 0; font-size: .85rem; }
.error { color: #ffaaa5 !important; }
.success { color: #80e0b9 !important; }
.access-note { padding: .8rem 1rem; border-left: 3px solid #80e0b9; background: #10271f; }
.centered { max-width: 38rem; margin: 12vh auto; text-align: center; }

@media (max-width: 760px) {
  .app-shell { display: block; }
  .sidebar { position: static; height: auto; padding: 1rem; }
  .brand-note { display: none; }
  nav { grid-template-columns: repeat(5, auto); overflow-x: auto; }
  nav a { padding: .55rem; font-size: .8rem; white-space: nowrap; }
  .auth-badge { position: static; display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; margin-top: .65rem; padding: .5rem .65rem; }
  .auth-badge .error { flex-basis: 100%; }
  .content { padding: 2.5rem 1rem; }
  .cards { grid-template-columns: 1fr; }
  .hero { padding: 2rem 0; }
  .message { max-width: 90%; }
}