:root {
  color-scheme: light;
  --bg: #FFFFFF; --surface: #FFFFFF; --surface-2: #F1F5F9; --text: #0F172A; --text-muted: #475569; --border: #E2E8F0;
  --accent: #2563EB; --on-accent: #FFFFFF; --online: #16A34A; --danger: #B91C1C;
  --icon: 20px; --icon-large: 24px; --app-height: 100dvh;
  font-family: 'IBM Plex Sans Thai', system-ui, sans-serif; font-size: 16px; line-height: 1.5; font-weight: 400;
  color: var(--text); background: var(--bg);
}
[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0B1120; --surface: #111827; --surface-2: #1F2937; --text: #F1F5F9; --text-muted: #94A3B8; --border: #263244;
  --accent: #2563EB; --on-accent: #FFFFFF; --online: #16A34A; --danger: #FCA5A5;
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); }
body.chatting { overflow: hidden; height: var(--app-height); }
[hidden] { display: none !important; }
button, input, textarea { font: inherit; }
button, .button { display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-width: 44px; min-height: 44px; border: 0; border-radius: 12px; padding: 8px 16px; background: var(--accent); color: var(--on-accent); cursor: pointer; font-size: 14px; font-weight: 500; text-decoration: none; transition: background 180ms, transform 180ms; }
button:active, .button:active { transform: scale(.97); }
button:disabled { opacity: .45; cursor: default; }
:where(button, a, input, textarea, [tabindex]):focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
input, textarea { min-width: 0; width: 100%; padding: 12px; border: 1px solid var(--border); border-radius: 12px; background: var(--surface); color: var(--text); font-size: 16px; line-height: 1.5; }
input { min-height: 48px; }
input::placeholder, textarea::placeholder { color: var(--text-muted); opacity: 1; }
textarea { resize: none; }
h1, h2, p { margin: 0; }
h1, h2 { line-height: 1.25; font-weight: 600; }
h1 { font-size: 22px; }
h2 { font-size: 18px; }
strong { font-weight: 600; }
small, time { font-size: 12px; color: var(--text-muted); }
label, legend, .field-label { font-size: 14px; font-weight: 500; }
.muted { color: var(--text-muted); }
.icon { width: var(--icon); height: var(--icon); flex-shrink: 0; vertical-align: middle; }
.icon-button, .avatar-button { padding: 8px; background: transparent; color: var(--text-muted); flex-shrink: 0; }
.icon-button:hover, .avatar-button:hover { background: var(--surface-2); }
.logo { display: inline-grid; place-items: center; width: 44px; height: 44px; flex-shrink: 0; border-radius: 12px; background: var(--accent); color: var(--on-accent); font-size: 28px; font-weight: 700; }
.login-screen { min-height: var(--app-height); display: grid; grid-template-columns: 1fr 1fr; }
.brand-panel { padding: 32px; display: flex; flex-direction: column; justify-content: center; gap: 24px; background: var(--surface-2); }
.brand-panel h1, .login-card h1 { font-size: 28px; font-weight: 700; }
.brand-panel p { color: var(--text-muted); }
.eyebrow { font-size: 12px; font-weight: 600; letter-spacing: .06em; }
.brand-art { display: grid; place-items: center; width: 240px; height: 240px; border: 1px solid var(--border); border-radius: 18px; background: var(--surface); color: var(--accent); }
.brand-art .icon { width: 96px; height: 96px; }
.login-card { display: grid; gap: 12px; width: min(100%, 440px); margin: auto; padding: 32px; }
.login-card label { margin-top: 8px; }
.login-card input, #login-button { min-height: 48px; }
.auth-modes, .theme-control { display: flex; gap: 4px; padding: 4px; border-radius: 12px; background: var(--surface-2); }
.auth-modes button { flex: 1; }
.auth-modes button[aria-pressed="false"], .theme-control button { background: transparent; color: var(--text-muted); }
.theme-control { width: fit-content; }
.theme-control button[aria-pressed="true"] { background: var(--surface); color: var(--text); }
.password-field { display: flex; align-items: center; border: 1px solid var(--border); border-radius: 12px; }
.password-field input { border: 0; }
.error { color: var(--danger); font-size: 14px; overflow-wrap: anywhere; }
.app { display: grid; grid-template-columns: 340px minmax(0,1fr); height: var(--app-height); max-width: 1680px; margin: auto; overflow: hidden; background: var(--bg); }
.sidebar { display: flex; flex-direction: column; gap: 16px; min-height: 0; padding: 16px; border-right: 1px solid var(--border); background: var(--surface); }
.brand { display: flex; align-items: center; gap: 8px; min-height: 56px; flex-shrink: 0; position: sticky; top: 0; background: var(--surface); z-index: 1; }
.brand strong { font-size: 18px; flex: 1; }
#me-button { padding: 0; }
.conversation-lists { flex: 1; overflow-y: auto; min-height: 0; }
.sidebar section { margin-bottom: 24px; }
.sidebar h2 { font-size: 12px; text-transform: uppercase; letter-spacing: .06em; color: var(--text-muted); display: flex; justify-content: space-between; padding: 8px; }
ul { list-style: none; margin: 0; padding: 0; }
.list-row { display: flex; gap: 8px; align-items: center; border-radius: 12px; padding: 8px; min-width: 0; }
.list-row:hover, .list-row.selected { background: var(--surface-2); }
.list-row.unread { background: color-mix(in srgb, var(--accent) 8%, var(--surface)); }
.list-button { background: transparent; color: var(--text); padding: 0; text-align: left; flex: 1; min-width: 0; font-weight: 400; }
.row-copy { min-width: 0; flex: 1; display: grid; gap: 4px; }
.row-top { display: flex; align-items: center; gap: 8px; }
.row-top strong { font-size: 16px; font-weight: 500; flex: 1; min-width: 0; overflow: hidden; white-space: nowrap; text-overflow: ellipsis; }
.row-top time { white-space: nowrap; }
.row-preview { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; color: var(--text-muted); font-size: 14px; }
.unread .row-top strong, .unread .row-preview { font-weight: 600; color: var(--text); }
.row-preview.is-typing { color: var(--accent); }
.badge { display: inline-grid; place-items: center; min-width: 20px; min-height: 20px; border-radius: 999px; padding: 0 4px; background: var(--accent); color: #fff; font-size: 12px; font-weight: 600; flex-shrink: 0; }
.avatar { display: inline-grid; place-items: center; width: 44px; height: 44px; border-radius: 999px; background: var(--avatar-color, var(--accent)); color: var(--on-accent); font-size: 14px; font-weight: 600; flex-shrink: 0; position: relative; }
.avatar img { width: 100%; height: 100%; border-radius: inherit; object-fit: cover; }
.avatar.online::after { content: ''; position: absolute; bottom: 0; right: 0; width: 12px; height: 12px; background: var(--online); border: 2px solid var(--surface); border-radius: 999px; }
.avatar-button { padding: 0; }
.avatar.small { width: 32px; height: 32px; font-size: 12px; }
.avatar.large { width: 96px; height: 96px; font-size: 28px; }
.online-list { display: flex; gap: 8px; overflow-x: auto; padding: 8px; }
.online-person { flex-shrink: 0; width: 64px; }
.online-person button { width: 100%; padding: 0; display: flex; flex-direction: column; background: transparent; color: var(--text); }
.online-person span:last-child { width: 100%; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: 12px; }
.list-empty { display: flex; gap: 8px; padding: 16px 8px; color: var(--text-muted); font-size: 14px; }
.secondary, .small-button { background: var(--surface-2); color: var(--text); }
.text-button { background: transparent; color: var(--text-muted); padding: 0 8px; }
.main { min-height: 0; min-width: 0; display: flex; flex-direction: column; position: relative; }
.room-header { display: flex; align-items: center; gap: 12px; padding: 8px 24px; min-height: 72px; border-bottom: 1px solid var(--border); flex-shrink: 0; background: var(--surface); }
.room-heading { flex: 1; min-width: 0; min-height: 44px; display: flex; flex-direction: column; justify-content: center; position: relative; }
.room-heading h1 { font-size: 18px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.room-heading h1[role="button"] { cursor: pointer; }
.room-heading h1[role="button"]::after { content: ''; position: absolute; inset: 0; }
#room-kind { font-size: 12px; color: var(--text-muted); }
#room-members { position: absolute; inset: 0; width: 100%; justify-content: flex-start; align-items: flex-end; padding: 24px 0 0; font-size: 12px; }
.mobile-back { display: none; position: relative; }
#back-unread { position: absolute; top: 0; right: 0; }
.conversation-area { display: flex; flex-direction: column; flex: 1; min-height: 0; position: relative; }
.messages { overflow-y: auto; overflow-x: hidden; overscroll-behavior-y: contain; min-height: 0; flex: 1; display: flex; flex-direction: column; padding: 24px; gap: 4px; }
.empty { margin: auto; padding: 32px 16px; max-width: 440px; text-align: center; color: var(--text-muted); }
.empty-symbol { display: grid; place-items: center; margin: 0 auto 24px; width: 96px; height: 96px; border-radius: 18px; background: var(--surface-2); color: var(--accent); }
.empty-symbol .icon { width: 48px; height: 48px; }
.empty h2 { color: var(--text); font-size: 22px; margin-bottom: 12px; }
.empty p { font-size: 14px; }
.date-separator, .system-message, .unread-divider { align-self: center; padding: 4px 12px; margin: 12px 0; border-radius: 999px; background: var(--surface-2); color: var(--text-muted); font-size: 12px; text-align: center; }
.unread-divider { color: var(--text); border: 1px solid var(--accent); }
.message-row { display: flex; align-items: flex-end; gap: 8px; width: 100%; margin-top: 12px; }
.message-row.grouped { margin-top: 0; }
.message-avatar { width: 44px; flex-shrink: 0; }
.message-avatar .avatar { width: 32px; height: 32px; font-size: 12px; }
.bubble-stack { min-width: 0; max-width: 75%; }
.message-name { background: transparent; color: var(--text-muted); font-size: 12px; font-weight: 600; padding: 0; justify-content: flex-start; margin-bottom: 4px; }
.message { padding: 8px 12px; border-radius: 18px; background: var(--surface-2); min-width: 0; }
.grouped .message { border-bottom-left-radius: 4px; }
.own { justify-content: flex-end; }
.own .message { background: var(--accent); color: var(--on-accent); }
.own.grouped .message { border-bottom-left-radius: 18px; border-bottom-right-radius: 4px; }
.message-text { font-size: 16px; line-height: 1.5; white-space: pre-wrap; overflow-wrap: anywhere; }
.message-row > time { font-size: 12px; padding-bottom: 4px; flex-shrink: 0; }
.ai-chip { display: inline-flex; gap: 4px; align-items: center; color: var(--text-muted); font-size: 12px; font-weight: 600; margin-bottom: 4px; }
.ai .message { border: 1px solid var(--border); }
.message.attachment { padding: 0; overflow: hidden; }
.file-card { display: flex; align-items: center; gap: 8px; padding: 12px; }
.file-info { min-width: 0; flex: 1; display: grid; gap: 4px; }
.file-info strong { overflow-wrap: anywhere; font-size: 14px; }
.file-info small { color: inherit; font-size: 12px; }
.file-download { padding: 8px; background: transparent; color: inherit; }
.image-button { padding: 0; display: block; background: transparent; width: 240px; max-width: 100%; border-radius: 18px; overflow: hidden; }
.image-preview { display: block; width: 240px; max-width: 100%; max-height: 320px; object-fit: cover; }
.image-status { padding: 16px; font-size: 14px; }
.typing { display: flex; align-items: center; gap: 8px; flex-shrink: 0; min-height: 44px; padding: 4px 24px; color: var(--text-muted); font-size: 12px; visibility: hidden; }
.typing.is-visible { visibility: visible; }
.typing-dots { display: inline-flex; align-items: center; justify-content: center; gap: 4px; padding: 12px; background: var(--surface-2); border-radius: 18px; }
.typing-dots i { width: 4px; height: 4px; background: var(--text-muted); border-radius: 999px; animation: typing 1200ms infinite; }
.typing-dots i:nth-child(2) { animation-delay: 200ms; }
.typing-dots i:nth-child(3) { animation-delay: 400ms; }
@keyframes typing { 50% { transform: translateY(-4px); } }
.composer-wrap { position: relative; flex-shrink: 0; border-top: 1px solid var(--border); background: var(--surface); padding-bottom: max(8px, env(safe-area-inset-bottom)); }
.composer { display: flex; gap: 8px; align-items: flex-end; padding: 8px 16px; }
.composer textarea { flex: 1; width: 0; min-height: 44px; max-height: 140px; padding: 8px 12px; background: var(--surface-2); border-color: transparent; }
#send-button { width: 44px; height: 44px; padding: 8px; border-radius: 999px; flex-shrink: 0; }
.composer-hint { color: var(--text-muted); font-size: 12px; text-align: center; padding: 0 16px; }
.sending-state { padding: 8px 16px; color: var(--text-muted); font-size: 12px; overflow-wrap: anywhere; }
.emoji-picker { position: absolute; bottom: 100%; right: 8px; width: min(320px, calc(100% - 16px)); max-height: calc(var(--app-height) * .5); overflow-y: auto; display: grid; grid-template-columns: repeat(6,1fr); padding: 8px; border: 1px solid var(--border); border-radius: 12px; background: var(--surface); z-index: 3; }
.emoji-picker button { padding: 4px; font-size: 22px; background: transparent; }
.new-messages { position: absolute; bottom: 56px; left: 50%; transform: translateX(-50%); border-radius: 999px; z-index: 2; white-space: nowrap; }
.drop-hint { position: absolute; inset: 16px; display: grid; place-content: center; background: var(--surface); border: 2px dashed var(--accent); border-radius: 12px; text-align: center; pointer-events: none; z-index: 4; }
dialog { width: min(440px, calc(100% - 32px)); max-height: calc(var(--app-height) - 32px); overflow-y: auto; padding: 0; border: 1px solid var(--border); border-radius: 18px; background: var(--surface); color: var(--text); }
dialog::backdrop { background: #0B112080; }
.modal-content { display: grid; gap: 16px; padding: 24px; }
.modal-heading { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.modal-heading h2 { font-size: 22px; }
.create-group { display: grid; gap: 12px; }
.photo-actions { display: flex; justify-content: center; gap: 8px; }
.avatar-preview { text-align: center; }
fieldset { border: 0; padding: 0; margin: 0; }
legend { margin-bottom: 12px; }
.color-options { display: flex; flex-wrap: wrap; gap: 8px; }
.color-option { background: var(--swatch); width: 44px; height: 44px; padding: 4px; border: 4px solid var(--surface); }
.color-option[aria-pressed="true"] { outline: 2px solid var(--text); }
#profile-card-content { display: grid; justify-items: center; gap: 16px; text-align: center; overflow-wrap: anywhere; }
#profile-card-content p { white-space: pre-wrap; }
.member-row { display: flex; align-items: center; gap: 8px; padding: 8px 0; }
.member-row .text-button { color: var(--text); overflow-wrap: anywhere; }
.member-row small { margin-left: auto; }
#lightbox { width: min(1000px, calc(100% - 24px)); padding: 16px; }
.lightbox-toolbar { display: flex; align-items: center; gap: 8px; margin-bottom: 16px; }
.lightbox-toolbar strong { flex: 1; min-width: 0; overflow-wrap: anywhere; font-size: 14px; }
#lightbox-image { display: block; max-width: 100%; max-height: calc(var(--app-height) - 160px); margin: auto; object-fit: contain; }
.toasts { position: fixed; bottom: 24px; right: 16px; width: min(360px, calc(100% - 32px)); display: grid; gap: 8px; z-index: 100; }
.toast { display: flex; align-items: center; gap: 8px; border: 1px solid var(--border); padding: 12px; border-radius: 12px; background: var(--surface); color: var(--text); font-size: 14px; box-shadow: 0 8px 32px #0002; }
.toast span { flex: 1; overflow-wrap: anywhere; }
.toast.error { border-color: var(--danger); }
.message-banner { position: fixed; top: max(8px, env(safe-area-inset-top)); left: 50%; transform: translateX(-50%); width: min(440px, calc(100% - 16px)); display: flex; gap: 8px; align-items: center; padding: 8px; background: var(--surface); border: 1px solid var(--border); border-radius: 18px; box-shadow: 0 8px 32px #0003; z-index: 50; animation: banner-in 200ms ease-out; touch-action: pan-y; }
.banner-open { flex: 1; min-width: 0; justify-content: flex-start; padding: 0; background: transparent; color: var(--text); text-align: left; }
.banner-copy { display: grid; min-width: 0; }
.banner-copy span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: 14px; color: var(--text-muted); }
@keyframes banner-in { from { opacity: 0; translate: 0 -16px; } to { opacity: 1; translate: 0 0; } }
.skeleton { width: 60%; min-height: 64px; margin: 8px 0; background: var(--surface-2); border-radius: 18px; }
.skeleton:nth-child(even) { align-self: flex-end; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; }
@media (max-width: 768px) {
  .login-screen { grid-template-columns: 1fr; }
  .brand-panel { display: none; }
  .login-card { padding: 24px; }
  .app { display: block; position: relative; width: 100%; }
  .sidebar, .main { position: absolute; inset: 0; width: 100%; height: 100%; transition: transform 200ms ease, visibility 200ms; }
  .sidebar { padding: max(8px, env(safe-area-inset-top)) 12px 8px; border: 0; }
  .main { transform: translateX(100%); visibility: hidden; background: var(--bg); }
  .room-open .sidebar { transform: translateX(-100%); visibility: hidden; }
  .room-open .main { transform: translateX(0); visibility: visible; }
  .mobile-back { display: inline-flex; }
  .room-header { height: 56px; min-height: 56px; padding: 0 8px; gap: 8px; }
  .room-header .avatar { width: 32px; height: 32px; font-size: 12px; }
  .room-heading h1 { font-size: 18px; }
  #room-members { padding: 24px 0 0; }
  #room-kind { line-height: 1.25; }
  .messages { padding: 12px 8px; }
  .bubble-stack { max-width: 80%; }
  .message-row:not(.own) .bubble-stack { max-width: calc(80% - 44px); }
  .message-row { gap: 4px; }
  .message-row > time { font-size: 12px; }
  .typing { padding: 4px 12px; }
  .composer { padding: 8px; gap: 4px; }
  .composer-hint { display: none; }
  .sheet { margin: auto 0 0; width: 100%; max-width: none; border-radius: 18px 18px 0 0; padding-bottom: env(safe-area-inset-bottom); }
  .modal-content { padding: 24px 16px; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
}

/* Photo dimensions are reserved before private attachment bytes arrive. */
.message.photo-message, .own .message.photo-message { padding: 0; background: transparent; overflow: hidden; border-radius: 18px 18px 18px 4px; }
.own .message.photo-message { border-radius: 18px 18px 4px 18px; }
.photo-message .image-button { min-width: 0; min-height: 0; max-width: 100%; border-radius: inherit; position: relative; color: var(--text-muted); }
.image-preview { width: 100%; height: 100%; max-height: none; }
.image-button.loading { background: var(--surface-2); }
.image-button.loading::after { content: ''; position: absolute; inset: 0; background: linear-gradient(90deg, transparent, var(--border), transparent); animation: photo-loading 1400ms infinite; }
.image-button.loading img { visibility: hidden; }
.image-status { display: grid; place-items: center; width: 100%; height: 100%; background: var(--surface-2); padding: 8px; font-size: 12px; }
@keyframes photo-loading { from { opacity: .3; } 50% { opacity: .8; } to { opacity: .3; } }
.read-receipt { display: block; margin-top: 4px; margin-left: auto; text-align: right; font-size: 12px; font-weight: 400; color: var(--text-muted); }
button.read-receipt { min-height: 44px; padding: 0; background: transparent; }
.file-card { max-width: 320px; }
.file-info strong { overflow: hidden; white-space: nowrap; text-overflow: ellipsis; }
.row-preview .icon, .banner-copy .icon { width: 16px; height: 16px; margin-right: 4px; }
#lightbox::backdrop { background: #0B1120e6; }
@media (max-width: 768px) {
  .photo-message .image-button { max-width: 70vw; }
  .message-row:has(.photo-message) .bubble-stack { max-width: min(70vw, calc(100% - 96px)); }
}