:root {
  --bg: #f6f5f2;
  --side: #ecebe6;
  --panel: #ffffff;
  --ink: #1d1d1b;
  --muted: #6b6a66;
  --line: #e2e0da;
  --mine: #1f4e79;
  --mine-ink: #ffffff;
  --note: #8a5a00;
  --hover: #e0dfd9;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #161615;
    --side: #1d1d1b;
    --panel: #22221f;
    --ink: #ecebe7;
    --muted: #9a9890;
    --line: #34332f;
    --mine: #3b6fa0;
    --mine-ink: #ffffff;
    --note: #e0b25a;
    --hover: #2c2b28;
  }
}
* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body { background: var(--bg); color: var(--ink); font: 15px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; }
[hidden] { display: none !important; }
button { font: inherit; cursor: pointer; }
button:disabled { opacity: .5; cursor: default; }

/* sign-in */
#login { display: flex; flex-direction: column; gap: 12px; max-width: 360px; margin: 12vh auto 0; padding: 0 16px; }
#login .title { font-weight: 600; font-size: 18px; margin-bottom: 8px; }
#login label { display: flex; flex-direction: column; gap: 4px; font-size: 13px; color: var(--muted); }
#login input { padding: 9px 10px; border: 1px solid var(--line); border-radius: 8px; background: var(--panel); color: var(--ink); font: inherit; }
#login button { padding: 10px 16px; border: 0; border-radius: 8px; background: var(--mine); color: var(--mine-ink); }
#login-error { color: var(--note); font-size: 13px; min-height: 1em; margin: 0; }

/* layout */
#app { display: flex; height: 100%; }
#side { width: 260px; flex: none; display: flex; flex-direction: column; background: var(--side); border-right: 1px solid var(--line); padding: 10px; gap: 8px; }
#new { padding: 9px 12px; border: 1px solid var(--line); border-radius: 8px; background: var(--panel); color: var(--ink); text-align: left; }
#new:hover { background: var(--hover); }
#list { flex: 1; overflow-y: auto; display: flex; flex-direction: column; gap: 2px; }
#list .group { color: var(--muted); font-size: 12px; margin: 10px 8px 2px; }
#list button { border: 0; background: transparent; color: var(--ink); text-align: left; padding: 7px 8px; border-radius: 6px;
               white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
#list button:hover { background: var(--hover); }
#list button.on { background: var(--hover); font-weight: 600; }
#list button .dot { display: inline-block; width: 6px; height: 6px; border-radius: 50%; background: var(--mine); margin-right: 6px; vertical-align: middle; }
.me { display: flex; justify-content: space-between; align-items: center; gap: 8px; font-size: 13px; color: var(--muted); border-top: 1px solid var(--line); padding: 8px 4px 0; }
.me a { color: var(--muted); }
#scrim { display: none; }

#main { flex: 1; min-width: 0; display: flex; flex-direction: column; }
header { display: flex; align-items: center; gap: 10px; padding: 12px 16px 10px; border-bottom: 1px solid var(--line); }
#menu { display: none; border: 0; background: transparent; color: var(--ink); padding: 4px; }
.title { font-weight: 600; }
.sub { color: var(--muted); font-size: 13px; }

#log { flex: 1; overflow-y: auto; padding: 20px 16px; display: flex; flex-direction: column; gap: 10px; width: 100%; max-width: 780px; margin: 0 auto; }
.empty { margin: auto; text-align: center; color: var(--muted); max-width: 420px; }
.empty .big { font-size: 20px; color: var(--ink); margin-bottom: 6px; }
.msg { max-width: 85%; padding: 8px 12px; border-radius: 12px; white-space: pre-wrap; overflow-wrap: anywhere; background: var(--panel); border: 1px solid var(--line); }
.msg.person { align-self: flex-end; background: var(--mine); color: var(--mine-ink); border-color: var(--mine); }
.msg.system { align-self: center; background: transparent; border-style: dashed; color: var(--note); font-size: 13px; }
.msg .file { display: block; font-size: 13px; opacity: .9; margin-bottom: 2px; }
.msg time { display: block; font-size: 11px; opacity: .7; margin-top: 2px; }
.wait { align-self: flex-start; color: var(--muted); font-size: 13px; }

#form { width: 100%; max-width: 780px; margin: 0 auto; padding: 8px 16px 10px; }
#form .row { display: flex; align-items: flex-end; gap: 8px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel); padding: 6px; }
#attach { display: flex; align-items: center; padding: 6px; color: var(--muted); cursor: pointer; border-radius: 6px; }
#attach:hover { background: var(--hover); }
textarea { flex: 1; resize: none; padding: 6px 4px; border: 0; outline: none; background: transparent; color: var(--ink); font: inherit; max-height: 30vh; }
#send { padding: 7px 14px; border: 0; border-radius: 8px; background: var(--mine); color: var(--mine-ink); }
#chip { display: inline-flex; align-items: center; gap: 6px; margin: 0 0 6px; padding: 3px 8px; border: 1px solid var(--line); border-radius: 6px; font-size: 13px; background: var(--panel); }
#chip button { border: 0; background: transparent; color: var(--muted); padding: 0 2px; }
footer { padding: 6px 2px 0; color: var(--muted); font-size: 12px; }

@media (max-width: 760px) {
  #side { position: fixed; z-index: 20; inset: 0 auto 0 0; transform: translateX(-100%); transition: transform .2s; }
  #app.open #side { transform: none; }
  #app.open #scrim { display: block; position: fixed; inset: 0; z-index: 10; background: rgba(0, 0, 0, .35); }
  #menu { display: block; }
  .msg { max-width: 92%; }
}