:root {
  --bg: #0a0e17;
  --surface: #111827;
  --surface-2: #1a2234;
  --border: #2a3548;
  --text: #e8edf5;
  --text-muted: #8896ab;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --accent-glow: rgba(59, 130, 246, 0.25);
  --success: #22c55e;
  --danger: #ef4444;
  --radius: 12px;
  --font: 'DM Sans', system-ui, sans-serif;
  --mono: 'JetBrains Mono', monospace;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.5;
}

.bg-grid {
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(rgba(59, 130, 246, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(59, 130, 246, 0.03) 1px, transparent 1px);
  background-size: 48px 48px;
  pointer-events: none;
  z-index: 0;
}

.container {
  position: relative;
  z-index: 1;
  max-width: 640px;
  margin: 0 auto;
  padding: 2rem 1.25rem 3rem;
}

.header {
  text-align: center;
  margin-bottom: 2rem;
}

.logo {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  margin-bottom: 0.5rem;
}

.logo-icon {
  font-size: 1.75rem;
  color: var(--accent);
}

.header h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.subtitle {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1rem;
}

.hidden { display: none !important; }

/* Tabs */
.tabs {
  display: flex;
  gap: 0.25rem;
  background: var(--surface-2);
  border-radius: 8px;
  padding: 4px;
  margin-bottom: 1.25rem;
}

.tab {
  flex: 1;
  padding: 0.6rem 1rem;
  border: none;
  background: transparent;
  color: var(--text-muted);
  font-family: var(--font);
  font-size: 0.9rem;
  font-weight: 500;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s;
}

.tab.active {
  background: var(--surface);
  color: var(--text);
  box-shadow: 0 1px 3px rgba(0,0,0,0.3);
}

.tab-content { display: none; }
.tab-content.active { display: block; }

.hint {
  color: var(--text-muted);
  font-size: 0.875rem;
  margin-bottom: 1rem;
}

/* Buttons */
.btn {
  font-family: var(--font);
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.7rem 1.25rem;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover { background: var(--accent-hover); }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }

.btn-ghost {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
}

.btn-ghost:hover { color: var(--text); border-color: var(--text-muted); }
.btn-sm { padding: 0.45rem 0.9rem; font-size: 0.8rem; }

/* Code box */
.code-box {
  margin-top: 1.25rem;
  padding: 1rem;
  background: var(--surface-2);
  border-radius: 8px;
  border: 1px dashed var(--border);
}

.code-box label {
  display: block;
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.5rem;
}

.code-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.code-row code,
.active-code {
  font-family: var(--mono);
  font-size: 1.5rem;
  font-weight: 500;
  letter-spacing: 0.15em;
  color: var(--accent);
}

.active-code { font-size: 0.9rem; }

/* Input */
.input-row {
  display: flex;
  gap: 0.5rem;
}

.input-row input,
#text-input {
  flex: 1;
  padding: 0.7rem 1rem;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-family: var(--mono);
  font-size: 1rem;
  letter-spacing: 0.1em;
  outline: none;
  transition: border-color 0.2s;
}

.input-row input:focus,
#text-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.status-text {
  margin-top: 0.75rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.status-text.error { color: var(--danger); }
.status-text.success { color: var(--success); }

/* Chat */
.chat-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border);
}

.peer-info {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--text-muted);
}

.status-dot.connected {
  background: var(--success);
  box-shadow: 0 0 8px var(--success);
}

.messages {
  height: 360px;
  overflow-y: auto;
  padding: 0.5rem 0;
  margin-bottom: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.messages::-webkit-scrollbar { width: 6px; }
.messages::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

.msg {
  max-width: 85%;
  padding: 0.65rem 0.9rem;
  border-radius: 10px;
  font-size: 0.9rem;
  word-break: break-word;
}

.msg.sent {
  align-self: flex-end;
  background: var(--accent);
  color: #fff;
  border-bottom-right-radius: 3px;
}

.msg.received {
  align-self: flex-start;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-bottom-left-radius: 3px;
}

.msg.system {
  align-self: center;
  background: transparent;
  color: var(--text-muted);
  font-size: 0.8rem;
  padding: 0.25rem;
}

.msg.file-msg {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.msg.file-msg svg { flex-shrink: 0; }

.msg.file-msg a {
  color: inherit;
  text-decoration: underline;
  cursor: pointer;
}

.msg .file-size {
  font-size: 0.75rem;
  opacity: 0.7;
}

.msg .time {
  display: block;
  font-size: 0.7rem;
  opacity: 0.6;
  margin-top: 0.25rem;
}

/* Input area */
.input-area {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.file-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 8px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.2s;
  flex-shrink: 0;
}

.file-btn:hover { color: var(--accent); border-color: var(--accent); }

/* Progress */
.transfer-progress {
  margin-bottom: 0.75rem;
}

.progress-bar {
  height: 4px;
  background: var(--surface-2);
  border-radius: 2px;
  overflow: hidden;
  margin-bottom: 0.35rem;
}

.progress-fill {
  height: 100%;
  background: var(--accent);
  width: 0%;
  transition: width 0.15s;
}

#progress-text {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.footer {
  text-align: center;
  margin-top: 1.5rem;
}

.footer p {
  font-size: 0.75rem;
  color: var(--text-muted);
}

@media (max-width: 480px) {
  .container { padding: 1.25rem 1rem 2rem; }
  .messages { height: 300px; }
  .code-row code { font-size: 1.2rem; }
}