:root {
  --background-light: #f7f9fc;
  --background-dark: #121212;
  --text-light: #202124;
  --text-dark: #e8eaed;
  --primary-color: #1A73E8;
  --user-message-bg-light: #e1f5fe;
  --user-message-bg-dark: #303134;
  --model-message-bg-light: #ffffff;
  --model-message-bg-dark: #202124;
  --border-color-light: #dadce0;
  --border-color-dark: #3c4043;
  --header-bg-light: #ffffff;
  --header-bg-dark: #202124;
  --sidebar-bg-light: #f1f3f4;
  --sidebar-bg-dark: #1e1e1e;
  --shadow: 0 1px 2px rgba(0,0,0,0.1), 0 2px 4px rgba(0,0,0,0.1);
  --avatar-bg: #d2e3fc;
  --avatar-bg-dark: #3c4043;
}

/* Default to light theme variables */
body {
  --background: var(--background-light);
  --text-color: var(--text-light);
  --user-message-bg: var(--user-message-bg-light);
  --model-message-bg: var(--model-message-bg-light);
  --border-color: var(--border-color-light);
  --header-bg: var(--header-bg-light);
  --sidebar-bg: var(--sidebar-bg-light);
  --avatar-bg-current: var(--avatar-bg);
}

/* Apply dark theme variables when .dark-mode class is present */
body.dark-mode {
  --background: var(--background-dark);
  --text-color: var(--text-dark);
  --user-message-bg: var(--user-message-bg-dark);
  --model-message-bg: var(--model-message-bg-dark);
  --border-color: var(--border-color-dark);
  --header-bg: var(--header-bg-dark);
  --sidebar-bg: var(--sidebar-bg-dark);
  --avatar-bg-current: var(--avatar-bg-dark);
}

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

html, body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  height: 100%;
  width: 100%;
  background-color: var(--background);
  color: var(--text-color);
  transition: background-color 0.3s, color 0.3s;
  overscroll-behavior: contain;
}

.app-layout {
    display: flex;
    /* Use dvh for mobile browsers to account for UI bars, with fallback variable */
    height: var(--app-height, 100dvh);
}

/* --- Sidebar Styles --- */
#sidebar {
    width: 260px;
    background-color: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    transition: margin-left 0.3s ease;
    padding: 0.75rem;
    gap: 0.75rem;
    flex-shrink: 0;
}
.sidebar-top {
    /* Container for the new chat button */
}
#new-chat-btn {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    width: 100%;
    padding: 0.75rem;
    background: var(--model-message-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-color);
    transition: background-color 0.2s;
}
#new-chat-btn:hover {
    background-color: rgba(0,0,0,0.05);
}
#new-chat-btn svg {
    width: 20px;
    height: 20px;
}
.sidebar-history {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}
.sidebar-header {
    padding: 0.25rem 0.5rem 0.75rem;
    border-bottom: 1px solid var(--border-color);
}
.sidebar-header h2 {
    font-size: 1.1rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.search-history-wrapper {
    position: relative;
}
#search-history-input {
    width: 100%;
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--model-message-bg);
    color: var(--text-color);
    font-size: 0.9rem;
}
#search-history-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(26, 115, 232, 0.2);
}

#sidebar nav {
    flex-grow: 1;
    overflow-y: auto;
    padding-top: 0.5rem;
}
#chat-history-list {
    list-style: none;
    padding: 0 0.5rem;
}
.chat-history-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.6rem 0.8rem;
    border-radius: 8px;
    cursor: pointer;
    margin-bottom: 0.25rem;
    font-size: 0.9rem;
    color: var(--text-color);
    transition: background-color 0.2s;
    position: relative;
}
.chat-title {
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    flex-grow: 1;
    padding-right: 5px; /* Space for actions */
}

/* Pinned Chat Styles */
.chat-history-item.pinned {
    font-weight: 500;
    background-color: rgba(26, 115, 232, 0.05);
}
body.dark-mode .chat-history-item.pinned {
    background-color: rgba(138, 180, 248, 0.1);
}
.chat-history-item.pinned .pin-btn {
    color: var(--primary-color);
}


.chat-history-item:hover {
    background-color: rgba(0,0,0,0.05);
}
.chat-history-item.active {
    background-color: var(--primary-color);
    color: white;
}
.chat-item-actions {
    display: flex;
    gap: 4px;
    opacity: 0;
    transition: opacity 0.2s;
    flex-shrink: 0;
    margin-left: 8px;
}
.chat-history-item:hover .chat-item-actions,
.chat-history-item.active .chat-item-actions {
    opacity: 1;
}
.chat-item-actions button {
    background: none;
    border: none;
    color: inherit;
    cursor: pointer;
    padding: 4px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}
.chat-item-actions button:hover {
    background-color: rgba(0,0,0,0.1);
}

.rename-input {
    width: 100%;
    padding: 0.3rem 0.5rem;
    border: 1px solid var(--primary-color);
    border-radius: 4px;
    background-color: var(--model-message-bg);
    color: var(--text-color);
    font-size: 0.9rem;
    outline: none;
}
.empty-history-message {
    text-align: center;
    padding: 2rem 1rem;
    color: var(--text-color);
    opacity: 0.6;
    font-size: 0.9rem;
}

.sidebar-footer {
    padding: 0.75rem;
    text-align: center;
    font-size: 0.8rem;
    color: var(--text-color);
    opacity: 0.6;
    flex-shrink: 0;
    border-top: 1px solid var(--border-color);
}

.chat-app {
  display: flex;
  flex-direction: column;
  height: 100%;
  width: 100%;
  flex-grow: 1;
  background-color: var(--background);
  position: relative;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.75rem 1rem;
  background-color: var(--header-bg);
  border-bottom: 1px solid var(--border-color);
  box-shadow: 0 1px 3px rgba(0,0,0,0.04);
  z-index: 10;
  transition: background-color 0.3s, border-color 0.3s;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.header-logo {
    height: 32px;
    width: 32px;
    flex-shrink: 0; /* Prevents logo from shrinking */
    object-fit: contain;
}

#menu-toggle-btn {
    display: none; /* Hidden by default on larger screens */
    background: transparent;
    border: none;
    cursor: pointer;
    color: var(--text-color);
}
#menu-toggle-btn svg {
    width: 28px;
    height: 28px;
}

header h1 {
  font-size: 1.25rem;
  font-weight: 500;
  color: var(--primary-color);
}

.header-controls {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.header-icon-btn {
    background: transparent;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    padding: 6px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.2s;
}
.header-icon-btn:hover {
    background-color: rgba(0,0,0,0.05);
}
.header-icon-btn svg {
    width: 24px;
    height: 24px;
}

#current-affairs-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background-color: #e8f0fe;
  border: 1px solid #d2e3fc;
  color: #1967d2;
  padding: 0.4rem 0.8rem;
  border-radius: 20px;
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 500;
  transition: background-color 0.2s, box-shadow 0.2s;
}
body.dark-mode #current-affairs-btn {
    background-color: #2e3a4e;
    border-color: #3c4043;
    color: #8ab4f8;
}

#current-affairs-btn:hover:not(:disabled) {
  background-color: #d2e3fc;
  box-shadow: 0 1px 2px rgba(0,0,0,0.05);
}
body.dark-mode #current-affairs-btn:hover:not(:disabled) {
    background-color: #3c4961;
}

#current-affairs-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

#current-affairs-btn svg {
  width: 20px;
  height: 20px;
}

/* Theme Switcher Styles */
.theme-switch-wrapper {
  display: flex;
  align-items: center;
}
.theme-switch {
  position: relative;
  display: inline-block;
  width: 50px;
  height: 26px;
}
.theme-switch input {
  opacity: 0;
  width: 0;
  height: 0;
}
.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: #ccc;
  transition: .4s;
  border-radius: 26px;
}
.slider:before {
  position: absolute;
  content: "";
  height: 20px;
  width: 20px;
  left: 3px;
  bottom: 3px;
  background-color: white;
  transition: .4s;
  border-radius: 50%;
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" height="24" viewBox="0 0 24 24" width="24"><path d="M0 0h24v24H0z" fill="none"/><path d="M12 7c-2.76 0-5 2.24-5 5s2.24 5 5 5 5-2.24 5-5-2.24-5-5-5zM2 13h2c.03-.29.08-.58.14-.85L2.92 10.9l1.41-1.41 1.22 1.22c.27-.06.56-.11.85-.14V8h2v2.15c.29.03.58.08.85.14l1.22-1.22 1.41 1.41-1.22 1.22c.06.27.11.56.14.85H22v-2h-2.15c-.03-.29-.08-.58-.14-.85l1.22-1.22-1.41-1.41-1.22 1.22c-.27-.06-.56-.11-.85-.14V6h-2v2.15c-.29-.03-.58.08-.85-.14l-1.22-1.22-1.41-1.41 1.22 1.22c-.06-.27-.11-.56-.14-.85H2v2zm18-2.15c.03.29.08.58.14.85L21.08 13.1l-1.41 1.41-1.22-1.22c-.27.06-.56.11-.85.14V16h-2v-2.15c-.29-.03-.58-.08-.85-.14l-1.22 1.22-1.41-1.41 1.22-1.22c.06-.27.11-.56.14-.85H2v2h2.15c-.03.29-.08.58-.14.85l-1.22 1.22 1.41 1.41 1.22-1.22c.27.06.56.11.85.14V20h2v-2.15c.29-.03.58.08.85.14l1.22 1.22 1.41 1.41-1.22-1.22c-.06-.27-.11-.56-.14-.85H22v-2h-2.15z" fill="orange"/></svg>');
  background-repeat: no-repeat;
  background-position: center;
}
input:checked + .slider {
  background-color: var(--primary-color);
}
input:checked + .slider:before {
  transform: translateX(24px);
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" enable-background="new 0 0 24 24" height="24" viewBox="0 0 24 24" width="24"><g><rect fill="none" height="24" width="24"/></g><g><path d="M12,3c-4.97,0-9,4.03-9,9s4.03,9,9,9s9-4.03,9-9c0-0.46-0.04-0.92-0.1-1.36c-0.98,1.37-2.58,2.26-4.4,2.26 c-2.98,0-5.4-2.42-5.4-5.4c0-1.81,0.89-3.42,2.26-4.4C12.92,3.04,12.46,3,12,3L12,3z" fill="yellow"/></g></svg>');
}

#chat-container {
  flex-grow: 1;
  overflow-y: auto;
  padding: 1.5rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem; /* Increased gap */
  scroll-behavior: smooth;
  -webkit-overflow-scrolling: touch; /* Smoother scrolling on iOS */
}

@keyframes slide-in-fade-in {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.message {
  max-width: 85%;
  word-wrap: break-word;
  animation: slide-in-fade-in 0.3s ease-out forwards;
  position: relative;
}

.message:hover .message-actions {
    opacity: 1;
    transform: translateY(0);
}

.message .content {
  padding: 0.8rem 1.2rem; /* Increased padding */
  border-radius: 18px;
  box-shadow: var(--shadow);
  flex-grow: 1;
  transition: background-color 0.3s;
  line-height: 1.7; /* Improved line height */
}

.message.user-message {
  align-self: flex-end;
}
.message.user-message .content {
  background-color: var(--primary-color);
  color: white;
  border-bottom-right-radius: 4px;
}

.message.model-message {
  align-self: flex-start;
  display: flex;
  align-items: flex-start;
  gap: 0.75rem; /* Increased gap */
  max-width: 90%;
}
.message.model-message .content {
  background-color: var(--model-message-bg);
  border-bottom-left-radius: 4px;
}

.avatar {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background-color: var(--avatar-bg-current);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary-color);
  transition: background-color 0.3s;
}
.avatar svg {
  width: 20px;
  height: 20px;
}

/* Message Actions (Copy, TTS, Feedback) Styles */
.message-actions {
    position: absolute;
    bottom: -10px;
    right: 12px;
    background: var(--model-message-bg);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 2px;
    display: flex;
    gap: 2px;
    opacity: 0;
    transition: opacity 0.2s, transform 0.2s;
    transform: translateY(5px);
    z-index: 1;
    box-shadow: var(--shadow);
}
.user-message .message-actions {
    right: auto;
    left: 12px;
}
.action-btn {
    background: transparent;
    border: none;
    border-radius: 50%;
    width: 28px;
    height: 28px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-color);
    padding: 0;
    transition: background-color 0.2s, color 0.2s;
}
.action-btn:hover {
    background: rgba(0,0,0,0.08);
}
.action-btn.selected {
    color: var(--primary-color);
    background: rgba(26, 115, 232, 0.1);
}
.action-btn svg {
    width: 18px;
    height: 18px;
}
.copy-btn .icon-copied,
.copy-btn.copied .icon-copy {
    display: none;
}
.copy-btn.copied .icon-copied {
    display: block;
    color: var(--primary-color);
}
.tts-btn .icon-stop-tts,
.tts-btn.is-playing .icon-play {
    display: none;
}
.tts-btn.is-playing .icon-stop-tts {
    display: block;
}


/* --- Professional Markdown Content Styles --- */
.message .content > *:first-child { margin-top: 0; }
.message .content > *:last-child { margin-bottom: 0; }

.message h1, .message h2, .message h3, .message h4 {
    margin: 1.5rem 0 0.75rem;
    font-weight: 600;
    color: var(--text-color);
}
.message h1 { font-size: 1.4em; }
.message h2 { 
    font-size: 1.2em; 
    padding-bottom: 0.3rem;
    border-bottom: 1px solid var(--border-color);
}
.message h3 { font-size: 1.1em; }
.message h4 { font-size: 1.0em; font-weight: 500; }

.message p { 
    margin-bottom: 0.75rem; 
}
.message ul, .message ol { 
    padding-left: 1.5rem; 
    margin-bottom: 1rem;
}
.message li {
    margin-bottom: 0.4rem;
}
.message li::marker {
    color: var(--primary-color);
}

.message code {
    background-color: rgba(0,0,0,0.05);
    padding: 0.2em 0.4em;
    margin: 0;
    font-size: 85%;
    border-radius: 6px;
    font-family: 'Fira Code', 'Courier New', monospace;
}
body.dark-mode .message code {
    background-color: rgba(255,255,255,0.1);
}

.message pre {
    background-color: #f0f2f5;
    padding: 1rem;
    border-radius: 8px;
    overflow-x: auto;
    margin: 1rem 0;
    border: 1px solid var(--border-color);
}
body.dark-mode .message pre {
    background-color: #2c2c2c;
}
.message pre code { padding: 0; margin: 0; font-size: 100%; background: none; border: none; }

.message blockquote {
    margin: 1rem 0;
    padding: 0.5rem 1rem;
    border-left: 4px solid var(--primary-color);
    background-color: var(--sidebar-bg);
    color: var(--text-color);
    opacity: 0.9;
}
.message blockquote p:last-child {
    margin-bottom: 0;
}

.message table {
    width: 100%;
    margin: 1rem 0;
    border-collapse: collapse;
    border: 1px solid var(--border-color);
}
.message th, .message td {
    padding: 0.6rem 0.8rem;
    border: 1px solid var(--border-color);
    text-align: left;
}
.message th {
    background-color: var(--sidebar-bg);
    font-weight: 600;
}


footer {
  padding: 0.5rem 1rem 1rem;
  background-color: var(--header-bg);
  border-top: 1px solid var(--border-color);
  transition: background-color 0.3s, border-color 0.3s;
  z-index: 5;
}

#chat-form {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  max-width: 900px;
  margin: 0 auto;
}

#prompt-input {
  flex-grow: 1;
  padding: 0.75rem 1rem;
  border-radius: 24px;
  border: 1px solid var(--border-color);
  background-color: var(--model-message-bg);
  color: var(--text-color);
  font-size: 1rem;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s, background-color 0.3s, color 0.3s;
}

#prompt-input:focus {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 2px rgba(26, 115, 232, 0.2);
}
#prompt-input:disabled {
    background-color: var(--sidebar-bg);
    cursor: not-allowed;
}


.chat-form-btn {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: none;
  color: white;
  cursor: pointer;
  flex-shrink: 0;
  transition: background-color 0.2s, transform 0.2s;
}

#chat-form button[type="submit"] {
    background-color: var(--primary-color);
}
#chat-form button[type="submit"]:hover:not(:disabled) {
  background-color: #1b66c9;
  transform: scale(1.05);
}
#chat-form button[type="submit"]:disabled {
  background-color: #9e9e9e;
  cursor: not-allowed;
}
#chat-form button[type="submit"] svg {
  width: 24px;
  height: 24px;
}
#chat-form button[type="submit"] .icon-stop {
    display: none;
}
#chat-form button[type="submit"].is-generating .icon-send {
    display: none;
}
#chat-form button[type="submit"].is-generating .icon-stop {
    display: block;
}

#voice-input-btn {
    background-color: transparent;
    color: var(--text-color);
}
#voice-input-btn:hover {
    background-color: rgba(0,0,0,0.05);
}
#voice-input-btn.is-recording {
    color: #fff;
    background-color: #ea4335;
    animation: pulse-red 1.5s infinite;
}
@keyframes pulse-red {
    0% { box-shadow: 0 0 0 0 rgba(234, 67, 53, 0.7); }
    70% { box-shadow: 0 0 0 10px rgba(234, 67, 53, 0); }
    100% { box-shadow: 0 0 0 0 rgba(234, 67, 53, 0); }
}


/* Loading animation */
.loading {
  display: flex;
  gap: 4px;
  padding: 0.5rem 0;
}
.loading span {
  width: 8px;
  height: 8px;
  background-color: var(--primary-color);
  border-radius: 50%;
  animation: pulse 1.4s infinite ease-in-out both;
}
.loading span:nth-child(1) { animation-delay: -0.32s; }
.loading span:nth-child(2) { animation-delay: -0.16s; }
@keyframes pulse {
  0%, 80%, 100% { transform: scale(0); }
  40% { transform: scale(1.0); }
}

#usage-limit-indicator {
    font-size: 0.75rem;
    text-align: center;
    color: var(--text-color);
    opacity: 0.7;
    margin-top: 0.5rem;
    padding: 0 1rem;
    max-width: 900px;
    margin: 0.5rem auto 0;
}

/* --- Responsive Design --- */
@media (max-width: 768px) {
    #sidebar {
        position: fixed;
        left: 0;
        top: 0;
        height: 100%;
        z-index: 200;
        margin-left: -260px; /* Hidden by default */
    }
    body.sidebar-open #sidebar {
        margin-left: 0;
        box-shadow: 4px 0 15px rgba(0,0,0,0.1);
    }
    body.sidebar-open .app-layout::after {
        content: '';
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: rgba(0,0,0,0.4);
        z-index: 199;
    }

    #menu-toggle-btn {
        display: block;
    }
    .header-controls #current-affairs-btn span {
        display: none;
    }
    .header-controls #current-affairs-btn {
        padding: 0.5rem;
        border-radius: 50%;
    }
    header h1 {
        font-size: 1.15rem;
    }
    #chat-container {
        padding: 1rem 0.75rem;
    }
    footer {
        padding: 0.5rem;
    }
    #chat-form {
        gap: 0.25rem;
    }
    #voice-input-btn {
        display: none; /* Can be enabled if desired for mobile */
    }
}