/* =================================================================
   Nexus AI Studio — Professional chatbot UI
   Design tokens (dark-first with explicit light overrides)
   ================================================================= */
:root[data-theme="dark"] {
  --bg-0: #0A0B0F;
  --bg-1: #0F1117;
  --bg-2: #161A22;
  --bg-3: #1C2230;
  --bg-card: #161A22;
  --bg-elev: #1F2533;
  --border: #232A3A;
  --border-soft: #1B2230;
  --text: #E6E8EE;
  --text-2: #B6BCCB;
  --text-3: #7C8499;
  --accent: #7C5CFF;
  --accent-2: #22D3EE;
  --accent-soft: rgba(124, 92, 255, 0.14);
  --accent-line: rgba(124, 92, 255, 0.35);
  --ok: #34D399;
  --warn: #FBBF24;
  --bad: #F87171;
  --code-bg: #0C0F16;
  --shadow-md: 0 10px 30px rgba(0,0,0,.35);
  --shadow-lg: 0 24px 60px rgba(0,0,0,.5);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
}
:root[data-theme="light"] {
  --bg-0: #F7F8FB;
  --bg-1: #FFFFFF;
  --bg-2: #F2F4F8;
  --bg-3: #E9EDF3;
  --bg-card: #FFFFFF;
  --bg-elev: #FFFFFF;
  --border: #E2E6EE;
  --border-soft: #ECEFF5;
  --text: #0F1117;
  --text-2: #404756;
  --text-3: #6B7385;
  --accent: #6B49F2;
  --accent-2: #0EA5E9;
  --accent-soft: rgba(107, 73, 242, 0.10);
  --accent-line: rgba(107, 73, 242, 0.32);
  --ok: #059669;
  --warn: #B45309;
  --bad: #DC2626;
  --code-bg: #F5F6FA;
  --shadow-md: 0 10px 24px rgba(15, 17, 23, .08);
  --shadow-lg: 0 24px 60px rgba(15, 17, 23, .15);
}

/* ---------- base ---------- */
* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; }
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg-0);
  color: var(--text);
  font-size: 14.5px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  overflow: hidden;
}
button { font-family: inherit; cursor: pointer; }
code, pre, .mono { font-family: 'JetBrains Mono', ui-monospace, monospace; }

/* ---------- topbar ---------- */
.topbar {
  display: flex; align-items: center; gap: 16px;
  padding: 10px 18px;
  background: var(--bg-1);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 50;
  height: 58px;
}
.brand { display:flex; align-items:center; gap: 10px; min-width: 240px; }
.logo { width: 30px; height: 30px; display: grid; place-items: center; }
.logo svg { width: 26px; height: 26px; }
.brand-text { display:flex; flex-direction: column; line-height: 1; }
.brand-name { font-weight: 800; letter-spacing: -0.01em; font-size: 16px; }
.brand-accent { background: linear-gradient(90deg, #7C5CFF, #22D3EE); -webkit-background-clip: text; background-clip: text; color: transparent; }
.brand-tag { font-size: 10.5px; color: var(--text-3); letter-spacing: 0.08em; text-transform: uppercase; margin-top: 2px; }

.topbar-center { flex: 1; display: flex; justify-content: center; }
.model-pill {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 7px 14px;
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 13px; cursor: pointer;
  transition: all .15s ease;
}
.model-pill:hover { background: var(--bg-3); border-color: var(--accent-line); }
.pill-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--ok); box-shadow: 0 0 0 3px rgba(52,211,153,.18); }
.pill-provider { font-weight: 600; }
.pill-sep { color: var(--text-3); }
.pill-model { color: var(--text-2); }
.pill-caret { width: 14px; height: 14px; color: var(--text-3); margin-left: 2px; }

.topbar-right { display:flex; align-items:center; gap: 8px; }
.icon-btn {
  background: transparent; border: 1px solid transparent;
  color: var(--text-2); width: 36px; height: 36px;
  display: grid; place-items: center;
  border-radius: 10px; transition: all .15s ease;
}
.icon-btn svg { width: 18px; height: 18px; }
.icon-btn:hover { background: var(--bg-2); color: var(--text); border-color: var(--border); }
.btn-primary {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 8px 14px;
  background: linear-gradient(135deg, #7C5CFF 0%, #5E3CF0 100%);
  color: white; border: 0;
  border-radius: 10px; font-weight: 600; font-size: 13px;
  box-shadow: 0 4px 14px rgba(124,92,255,.35);
  transition: transform .12s ease, box-shadow .12s ease;
}
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 6px 20px rgba(124,92,255,.5); }
.btn-primary svg { width: 16px; height: 16px; }
.btn-ghost {
  background: transparent; color: var(--text-2);
  border: 1px solid var(--border);
  border-radius: 10px; padding: 8px 14px; font-weight: 500; font-size: 13px;
}
.btn-ghost:hover { background: var(--bg-2); color: var(--text); }

/* theme icon toggle */
.i-sun { display: none; }
:root[data-theme="light"] .i-moon { display: none; }
:root[data-theme="light"] .i-sun { display: block; }

/* ---------- layout ---------- */
.layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  height: calc(100vh - 58px);
}
.sidebar {
  background: var(--bg-1);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 16px 12px;
  display: flex; flex-direction: column;
}
.side-section { margin-bottom: 22px; }
.side-title {
  font-size: 11px; font-weight: 600;
  color: var(--text-3); text-transform: uppercase; letter-spacing: 0.1em;
  padding: 0 8px; margin-bottom: 8px;
}
.side-tool {
  display: flex; align-items: center; gap: 10px;
  width: 100%; padding: 8px 10px;
  background: transparent; border: 1px solid transparent;
  border-radius: 10px; color: var(--text);
  margin-bottom: 4px; text-align: left;
  transition: all .12s ease;
}
.side-tool:hover { background: var(--bg-2); border-color: var(--border); }
.tool-icon {
  width: 32px; height: 32px; min-width: 32px;
  border-radius: 9px;
  display: grid; place-items: center;
  box-shadow: 0 2px 8px rgba(0,0,0,.15);
}
.tool-icon svg { width: 16px; height: 16px; }
.tool-name { font-size: 13px; font-weight: 600; }
.tool-desc { font-size: 11.5px; color: var(--text-3); margin-top: 2px; }

.history-list { padding: 0 4px; }
.history-empty { font-size: 12px; color: var(--text-3); padding: 8px 6px; }
.history-item {
  padding: 8px 10px; border-radius: 8px;
  font-size: 13px; color: var(--text-2);
  cursor: pointer; margin-bottom: 2px;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.history-item:hover { background: var(--bg-2); color: var(--text); }
.history-item.active { background: var(--accent-soft); color: var(--text); }

.side-footer { margin-top: auto; padding: 12px 4px 4px; border-top: 1px solid var(--border); }
.usage-row { display:flex; justify-content: space-between; font-size: 12px; padding: 4px 6px; color: var(--text-3); }
.usage-row b { color: var(--text); }
.status-ok { color: var(--ok); font-weight: 500; }

/* ---------- main ---------- */
.main { display: flex; flex-direction: column; overflow: hidden; background: var(--bg-0); }

/* welcome */
.welcome {
  flex: 1; overflow-y: auto;
  padding: 28px 28px 24px;
  display: flex; align-items: flex-start; justify-content: center;
}
.hero { max-width: 920px; width: 100%; }
.hero-badge {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 12px; border-radius: 999px;
  background: var(--accent-soft);
  border: 1px solid var(--accent-line);
  color: var(--text); font-size: 12px; font-weight: 500;
}
.badge-dot { width: 6px; height: 6px; border-radius: 50%; background: var(--accent); box-shadow: 0 0 0 4px rgba(124,92,255,.18); }

.hero-title {
  font-size: clamp(28px, 4.2vw, 44px);
  font-weight: 800; letter-spacing: -0.02em;
  margin: 18px 0 10px;
  line-height: 1.1;
}
.grad { background: linear-gradient(90deg, #7C5CFF, #22D3EE); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero-sub { color: var(--text-2); font-size: 15.5px; max-width: 720px; margin-bottom: 24px; }

.templates {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 12px;
}
.tpl-card {
  padding: 14px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  cursor: pointer;
  transition: all .15s ease;
}
.tpl-card:hover {
  transform: translateY(-2px);
  border-color: var(--accent-line);
  box-shadow: var(--shadow-md);
}
.tpl-icon {
  width: 36px; height: 36px; border-radius: 10px;
  display: grid; place-items: center;
  margin-bottom: 10px;
}
.tpl-name { font-weight: 600; font-size: 14px; margin-bottom: 4px; }
.tpl-desc { color: var(--text-3); font-size: 12.5px; }

.features-strip {
  display: flex; gap: 16px; margin-top: 28px; padding: 14px 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}
.feat { display: flex; flex-direction: column; align-items: flex-start; }
.feat b { font-size: 22px; font-weight: 700; }
.feat span { font-size: 11px; color: var(--text-3); text-transform: uppercase; letter-spacing: 0.08em; }
.feat:not(:last-child) { padding-right: 22px; border-right: 1px solid var(--border); }

/* ---------- messages ---------- */
.messages {
  flex: 1; overflow-y: auto;
  padding: 24px 28px 8px;
  display: none;
  flex-direction: column;
  gap: 18px;
}
.main.chatting .welcome { display: none; }
.main.chatting .messages { display: flex; }

.msg { display: flex; gap: 12px; max-width: 980px; width: 100%; margin: 0 auto; }
.msg-avatar {
  width: 32px; height: 32px; min-width: 32px;
  border-radius: 10px;
  display: grid; place-items: center;
  font-weight: 700; font-size: 12px;
  color: white;
}
.msg.user .msg-avatar { background: linear-gradient(135deg,#3B82F6,#1E40AF); }
.msg.assistant .msg-avatar { background: linear-gradient(135deg,#7C5CFF,#22D3EE); }
.msg-body { flex: 1; min-width: 0; }
.msg-meta { font-size: 12px; color: var(--text-3); margin-bottom: 4px; display: flex; gap: 8px; align-items: center; }
.msg-meta b { color: var(--text); }
.msg-content {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px 16px;
  font-size: 14.5px;
  line-height: 1.7;
  white-space: pre-wrap;
  word-wrap: break-word;
  overflow-wrap: anywhere;
}
.msg.user .msg-content { background: var(--accent-soft); border-color: var(--accent-line); }
.msg-content code {
  background: var(--code-bg);
  padding: 1px 6px; border-radius: 4px;
  font-size: 13px;
}
.msg-content pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  padding: 12px; border-radius: 8px;
  overflow-x: auto;
  font-size: 13px; line-height: 1.55;
  white-space: pre;
}
.msg-actions { display: flex; gap: 6px; margin-top: 6px; }
.msg-action {
  font-size: 11.5px; color: var(--text-3);
  background: transparent; border: 1px solid transparent;
  padding: 4px 8px; border-radius: 6px;
}
.msg-action:hover { background: var(--bg-2); color: var(--text); border-color: var(--border); }

.typing { display: inline-flex; gap: 4px; }
.typing span {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--text-3);
  animation: blink 1.2s infinite;
}
.typing span:nth-child(2) { animation-delay: .2s; }
.typing span:nth-child(3) { animation-delay: .4s; }
@keyframes blink { 0%, 60%, 100% { opacity: 0.3; } 30% { opacity: 1; } }

/* ---------- composer ---------- */
.composer-wrap {
  padding: 12px 28px 18px;
  background: linear-gradient(180deg, transparent, var(--bg-0) 30%);
}
.composer {
  max-width: 980px; margin: 0 auto;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 10px 12px 8px;
  box-shadow: var(--shadow-md);
  transition: border-color .15s ease, box-shadow .15s ease;
}
.composer:focus-within { border-color: var(--accent-line); box-shadow: 0 8px 28px rgba(124,92,255,.15); }
.composer-top { display: flex; gap: 6px; align-items: center; margin-bottom: 6px; }
.chip {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 5px 10px;
  font-size: 12px; font-weight: 500;
  background: var(--bg-2);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 999px;
}
.chip:hover { background: var(--bg-3); }
.chip.ghost { background: transparent; color: var(--text-2); }
.chip.ghost:hover { background: var(--bg-2); color: var(--text); }
.chip svg { width: 13px; height: 13px; }
.composer-spacer { flex: 1; }
.temp-control { display: flex; align-items: center; gap: 8px; }
.temp-label { font-size: 11.5px; color: var(--text-3); }
.temp-control input[type=range] { width: 100px; }
.temp-val { font-size: 11.5px; color: var(--text); font-family: 'JetBrains Mono', monospace; min-width: 32px; }

.composer-row { display: flex; align-items: flex-end; gap: 8px; }
.composer textarea {
  flex: 1; background: transparent; color: var(--text);
  border: 0; outline: none;
  resize: none; max-height: 260px; min-height: 28px;
  padding: 8px 6px;
  font-size: 14.5px; font-family: inherit; line-height: 1.55;
}
.send-btn {
  width: 38px; height: 38px;
  display: grid; place-items: center;
  background: linear-gradient(135deg, #7C5CFF, #22D3EE);
  border: 0; border-radius: 10px;
  color: white;
  box-shadow: 0 4px 12px rgba(124,92,255,.4);
  transition: all .15s ease;
}
.send-btn svg { width: 16px; height: 16px; }
.send-btn:hover { transform: scale(1.05); }
.send-btn:disabled { opacity: 0.5; cursor: not-allowed; transform: none; }

.composer-foot {
  display: flex; justify-content: space-between;
  font-size: 11px; color: var(--text-3); padding: 4px 4px 0;
}
.composer-foot .right { color: var(--text-3); }
.composer-foot b { color: var(--text-2); }

/* ---------- overlays ---------- */
.overlay {
  position: fixed; inset: 0;
  background: rgba(8,10,16,.65);
  backdrop-filter: blur(6px);
  z-index: 100;
  display: grid; place-items: center;
  padding: 20px;
  animation: fadeIn .15s ease;
}
.overlay[hidden] {
  display: none !important;
}
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
.model-picker, .settings-panel, .tool-panel {
  background: var(--bg-1);
  border: 1px solid var(--border);
  border-radius: 16px;
  width: 100%; max-width: 720px;
  max-height: 86vh; overflow: hidden;
  display: flex; flex-direction: column;
  box-shadow: var(--shadow-lg);
}
.mp-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 18px;
  border-bottom: 1px solid var(--border);
}
.mp-header h3 { margin: 0; font-size: 15px; font-weight: 700; }
.mp-search {
  width: calc(100% - 36px); margin: 14px 18px 0;
  padding: 10px 12px;
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: 10px; color: var(--text);
  font-size: 13px; font-family: inherit;
  outline: none;
}
.mp-search:focus { border-color: var(--accent-line); }
.mp-body { overflow-y: auto; padding: 12px 18px 18px; }

.provider-block { margin-bottom: 16px; }
.provider-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 8px 4px; margin-bottom: 4px;
}
.provider-head-left { display: flex; align-items: center; gap: 10px; }
.provider-logo {
  width: 24px; height: 24px; border-radius: 6px;
  display: grid; place-items: center;
  font-size: 11px; font-weight: 800; color: white;
}
.provider-name { font-weight: 700; font-size: 13.5px; }
.provider-badge {
  font-size: 10.5px; font-weight: 600;
  padding: 2px 7px; border-radius: 999px;
  background: var(--bg-2); border: 1px solid var(--border);
  color: var(--text-3);
}
.provider-badge.free { color: var(--ok); border-color: rgba(52,211,153,.3); }
.provider-badge.proxy-only { color: var(--warn); border-color: rgba(251,191,36,.3); }

.model-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 6px; }
.model-card {
  padding: 9px 11px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 9px;
  font-size: 12.5px; color: var(--text);
  cursor: pointer; transition: all .12s ease;
  text-align: left;
  display: flex; align-items: center; justify-content: space-between; gap: 8px;
}
.model-card:hover { background: var(--bg-2); border-color: var(--accent-line); }
.model-card.active { background: var(--accent-soft); border-color: var(--accent-line); color: var(--text); }
.model-card .mc-name { font-family: 'JetBrains Mono', monospace; font-size: 12px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.model-card .mc-default { font-size: 9.5px; color: var(--accent-2); font-weight: 700; }

/* settings */
.settings-body { padding: 18px; overflow-y: auto; }
.set-group { margin-bottom: 16px; }
.set-label {
  display: block; font-size: 12px; font-weight: 600;
  color: var(--text-2); margin-bottom: 6px;
}
.set-hint { font-weight: 400; color: var(--text-3); margin-left: 6px; font-family: 'JetBrains Mono', monospace; font-size: 11px; }
.set-input {
  width: 100%; padding: 10px 12px;
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: 10px; color: var(--text);
  font-size: 13px; font-family: inherit;
  outline: none;
}
.set-input:focus { border-color: var(--accent-line); }
textarea.set-input { font-family: 'JetBrains Mono', monospace; font-size: 12.5px; line-height: 1.5; resize: vertical; }
.set-segments { display: inline-flex; background: var(--bg-2); border: 1px solid var(--border); border-radius: 10px; padding: 3px; }
.seg {
  background: transparent; border: 0;
  padding: 6px 14px; font-size: 12.5px; font-weight: 500;
  color: var(--text-2); border-radius: 7px;
}
.seg.active { background: var(--accent); color: white; }
.set-actions { display: flex; gap: 8px; justify-content: flex-end; margin-top: 16px; }
.set-note {
  margin-top: 18px; padding: 12px;
  background: var(--bg-2); border: 1px solid var(--border);
  border-radius: 10px; font-size: 12px; color: var(--text-2);
}
.set-note code { color: var(--accent-2); }

/* tool panel */
.tool-body { padding: 18px; overflow-y: auto; }
.tool-foot {
  padding: 12px 18px; border-top: 1px solid var(--border);
  display: flex; gap: 8px; justify-content: flex-end;
}
.tf-row { margin-bottom: 14px; }
.tf-label { display: block; font-size: 12.5px; font-weight: 600; color: var(--text-2); margin-bottom: 6px; }
.tf-input, .tf-textarea, .tf-select {
  width: 100%; padding: 10px 12px;
  background: var(--bg-2); border: 1px solid var(--border);
  border-radius: 10px; color: var(--text);
  font-size: 13.5px; font-family: inherit; outline: none;
}
.tf-textarea { resize: vertical; min-height: 100px; }
.tf-input:focus, .tf-textarea:focus, .tf-select:focus { border-color: var(--accent-line); }
.tf-row-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }

/* toasts */
.toasts {
  position: fixed; bottom: 20px; right: 20px; z-index: 200;
  display: flex; flex-direction: column; gap: 8px;
}
.toast {
  padding: 12px 16px;
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: 10px; box-shadow: var(--shadow-md);
  font-size: 13px;
  animation: slideIn .2s ease;
  max-width: 340px;
}
.toast.ok { border-left: 3px solid var(--ok); }
.toast.err { border-left: 3px solid var(--bad); }
.toast.warn { border-left: 3px solid var(--warn); }
@keyframes slideIn { from { opacity: 0; transform: translateX(20px); } to { opacity: 1; transform: translateX(0); } }

/* responsive */
@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar { display: none; }
  .topbar .brand-text { display: none; }
  .brand { min-width: 40px; }
  .welcome, .messages, .composer-wrap { padding-left: 14px; padding-right: 14px; }
  .templates { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 560px) {
  .templates { grid-template-columns: 1fr; }
  .topbar-center .model-pill .pill-sep, .topbar-center .model-pill .pill-model { display: none; }
}