:root { color-scheme: light; font-family: Inter, ui-sans-serif, system-ui, sans-serif; color: #18251f; background: #f2f6f3; }
* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; background: radial-gradient(circle at top left, #dcecdf, transparent 38%), #f2f6f3; }
.shell { width: min(820px, calc(100% - 32px)); margin: 0 auto; padding: 42px 0 24px; }
header { display: flex; gap: 16px; align-items: center; margin-bottom: 24px; }
.mark { display: grid; place-items: center; width: 58px; height: 58px; border-radius: 16px; color: white; background: #155f3d; font-weight: 800; }
h1 { margin: 0; font-size: clamp(1.7rem, 4vw, 2.4rem); }
header p, .notice { margin: 5px 0 0; color: #607069; }
.messages { min-height: 52vh; display: flex; flex-direction: column; gap: 14px; padding: 22px; border: 1px solid #d9e2dc; border-radius: 20px; background: rgba(255,255,255,.86); box-shadow: 0 16px 50px rgba(35,67,50,.08); }
.message { max-width: 86%; padding: 13px 15px; border-radius: 16px; line-height: 1.55; white-space: pre-wrap; }
.assistant { align-self: flex-start; background: #edf2ee; }
.user { align-self: flex-end; color: white; background: #155f3d; }
.message small { display: block; margin-top: 9px; color: #607069; font-size: .75rem; }
.pending { opacity: .65; }
.error { color: #8c2525; background: #fdeaea; }
form { display: grid; grid-template-columns: 1fr auto; gap: 10px; margin-top: 14px; }
textarea { width: 100%; resize: none; padding: 14px 16px; border: 1px solid #cad6ce; border-radius: 14px; font: inherit; outline: none; }
textarea:focus { border-color: #155f3d; box-shadow: 0 0 0 3px rgba(21,95,61,.12); }
button { padding: 0 24px; border: 0; border-radius: 14px; color: white; background: #155f3d; font: inherit; font-weight: 700; cursor: pointer; }
button:disabled { opacity: .55; cursor: wait; }
.notice { text-align: center; font-size: .8rem; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); }
@media (max-width: 560px) { .shell { width: min(100% - 20px, 820px); padding-top: 22px; } .messages { padding: 14px; } form { grid-template-columns: 1fr; } button { min-height: 48px; } }