:root { color-scheme: dark; font-family: Inter, ui-sans-serif, system-ui, sans-serif; background: #10131a; color: #eff3f8; }
* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; display: grid; place-items: center; padding: 24px; background: radial-gradient(circle at 20% 0%, #263657, transparent 42%), #10131a; }
.app-shell { width: min(100%, 760px); }
header { margin: 0 0 20px; }
h1, h2, p { margin: 0; }
h1 { font-size: clamp(2.25rem, 7vw, 4rem); letter-spacing: -.06em; }
h2 { font-size: 1.25rem; }
.eyebrow { color: #91b8ff; font-size: .75rem; font-weight: 800; letter-spacing: .14em; margin-bottom: 8px; }
.subtitle { color: #aeb8c8; margin-top: 8px; }
.name-panel, .chat-panel { background: rgba(21, 27, 38, .88); border: 1px solid #303b51; border-radius: 18px; box-shadow: 0 20px 80px rgba(0,0,0,.25); padding: 20px; }
.name-panel form { margin-top: 18px; }
label { display: block; font-size: .9rem; font-weight: 650; margin-bottom: 7px; }
.input-row, .message-form { display: flex; gap: 9px; }
input { min-width: 0; width: 100%; border: 1px solid #46546f; border-radius: 10px; padding: 12px 14px; background: #111722; color: inherit; font: inherit; }
input:focus { outline: 3px solid #417af744; border-color: #79a5ff; }
button { cursor: pointer; border: 0; border-radius: 10px; padding: 12px 16px; background: #79a5ff; color: #0a1325; font: inherit; font-weight: 750; white-space: nowrap; }
button:disabled { cursor: not-allowed; opacity: .55; }
.chat-panel { padding: 0; overflow: hidden; }
.chat-topbar { display: flex; align-items: center; justify-content: space-between; padding: 15px 20px; border-bottom: 1px solid #303b51; color: #bfc9d9; font-size: .9rem; }
.text-button { padding: 4px; background: none; color: #91b8ff; }
.messages { height: min(55vh, 460px); overflow-y: auto; list-style: none; margin: 0; padding: 18px 20px; display: grid; align-content: start; gap: 16px; }
.message-meta { display: flex; align-items: baseline; gap: 8px; }
.message-meta time { color: #8792a5; font-size: .75rem; }
.chat-message p { color: #d5dce7; line-height: 1.45; margin-top: 3px; overflow-wrap: anywhere; }
.system-message { color: #8f9aad; font-size: .82rem; text-align: center; }
.message-form { border-top: 1px solid #303b51; padding: 14px; }
.error { color: #ffabb7; font-size: .85rem; min-height: 1.25em; margin-top: 8px; }
.chat-panel .error { padding: 0 14px 10px; margin: 0; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
@media (max-width: 520px) { body { padding: 14px; } .input-row { flex-direction: column; } .input-row button { width: 100%; } .messages { height: 56vh; } .message-form button { padding-inline: 13px; } }