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

:root {
  --bg-color: #ffffff;
  --header-bg: #f8f9fa;
  --text-color: #212529;
  --border-color: #dee2e6;
  --chatbox-bg: #f1f3f5;
  --primary-color: #007bff;
  --primary-hover: #0056b3;
  --bubble-bg: #e9ecef;
  --bubble-text: #212529;
  --system-msg-color: #6c757d;
  --input-bg: #ffffff;
}

[data-theme="dark"] {
  --bg-color: #1a1a1b;
  --header-bg: #2d2d2e;
  --text-color: #e4e6eb;
  --border-color: #3e4042;
  --chatbox-bg: #121212;
  --primary-color: #2d88ff;
  --primary-hover: #1b74e4;
  --bubble-bg: #3e4042;
  --bubble-text: #e4e6eb;
  --system-msg-color: #b0b3b8;
  --input-bg: #242526;
}

html, body {
  height: 100%;
  overflow: hidden;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.app-container {
  display: flex;
  flex-direction: column;
  height: 100vh;
  height: 100dvh;
  max-width: 1000px;
  margin: 0 auto;
  border-left: 1px solid var(--border-color);
  border-right: 1px solid var(--border-color);
}

/* Navbar Styles */
.navbar {
  padding: 0.5rem 1.5rem;
  background-color: var(--header-bg);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  flex-shrink: 0;
}

.back-button {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  color: var(--primary-color);
  font-weight: 500;
  transition: color 0.2s;
}

.back-button:hover {
  color: var(--primary-hover);
}

.back-button .icon {
  font-size: 1.2rem;
}

/* Overlay Styles */
.overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.85);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1000;
  backdrop-filter: blur(4px);
}

.login-box {
  background: var(--header-bg);
  padding: 2.5rem;
  border-radius: 16px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
  text-align: center;
  width: 90%;
  max-width: 400px;
}

.login-box h2 {
  margin-bottom: 1.5rem;
  font-size: 1.5rem;
}

.login-box input {
  width: 100%;
  padding: 0.875rem;
  margin-bottom: 1rem;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background: var(--input-bg);
  color: var(--text-color);
  font-size: 1rem;
}

.login-box button {
  width: 100%;
  padding: 0.875rem;
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  font-size: 1rem;
  transition: background 0.2s;
}

.login-box button:hover {
  background: var(--primary-hover);
}

.chat-header {
  padding: 1rem 1.5rem;
  background-color: var(--header-bg);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-shrink: 0;
}

.chat-header h1 {
  font-size: 1.25rem;
  font-weight: 600;
}

#theme-toggle {
  background: none;
  border: 1px solid var(--border-color);
  padding: 0.5rem;
  border-radius: 8px;
  cursor: pointer;
  color: var(--text-color);
  transition: background-color 0.2s;
}

#theme-toggle:hover {
  background-color: var(--bubble-bg);
}

.chatbox {
  flex: 1;
  overflow-y: auto;
  padding: 1.5rem;
  background-color: var(--chatbox-bg);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.chatbox p {
  max-width: 80%;
  padding: 0.75rem 1rem;
  border-radius: 12px;
  background-color: var(--bubble-bg);
  color: var(--bubble-text);
  word-wrap: break-word;
  align-self: flex-start;
  box-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

.chatbox .system-message {
  align-self: center;
  background: none;
  box-shadow: none;
  color: var(--system-msg-color);
  font-size: 0.875rem;
  text-align: center;
  max-width: 100%;
}

.input-container {
  padding: 1rem 1.5rem;
  padding-bottom: calc(1rem + env(safe-area-inset-bottom));
  background-color: var(--header-bg);
  border-top: 1px solid var(--border-color);
  display: flex;
  gap: 0.75rem;
  flex-shrink: 0;
}

#chat {
  flex: 1;
  padding: 0.75rem 1rem;
  border: 1px solid var(--border-color);
  border-radius: 20px;
  background-color: var(--input-bg);
  color: var(--text-color);
  outline: none;
  transition: border-color 0.2s;
}

#chat:focus {
  border-color: var(--primary-color);
}

#send_button {
  padding: 0.75rem 1.5rem;
  background-color: var(--primary-color);
  color: white;
  border: none;
  border-radius: 20px;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 0.2s;
}

#send_button:hover {
  background-color: var(--primary-hover);
}

/* Scrollbar styling */
.chatbox::-webkit-scrollbar {
  width: 6px;
}

.chatbox::-webkit-scrollbar-track {
  background: transparent;
}

.chatbox::-webkit-scrollbar-thumb {
  background-color: var(--border-color);
  border-radius: 10px;
}