/* ========== Base ========== */
:root {
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --primary-light: #eef2ff;
  --success: #10b981;
  --danger: #ef4444;
  --warning: #f59e0b;
  --bg: #f8fafc;
  --card: #ffffff;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.1);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ========== Header / Nav ========== */
.navbar {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow);
}

.navbar .logo {
  font-size: 20px;
  font-weight: 700;
  color: var(--primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.navbar .nav-links {
  display: flex;
  gap: 8px;
  align-items: center;
}

.navbar .nav-links a, .navbar .nav-links button {
  padding: 8px 16px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  transition: all 0.2s;
}

.navbar .nav-links a {
  color: var(--text-muted);
}
.navbar .nav-links a:hover, .navbar .nav-links a.active {
  color: var(--primary);
  background: var(--primary-light);
  text-decoration: none;
}

.navbar .user-info {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 14px;
}

.navbar .user-avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 14px;
}

/* ========== Container ========== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px;
}

/* ========== Cards ========== */
.card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
  border: 1px solid var(--border);
}

.card-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 16px;
}

/* ========== Buttons ========== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: all 0.2s;
  text-decoration: none;
}

.btn:hover { text-decoration: none; transform: translateY(-1px); }

.btn-primary {
  background: var(--primary);
  color: white;
}
.btn-primary:hover { background: var(--primary-hover); }

.btn-outline {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
}
.btn-outline:hover { background: var(--bg); }

.btn-danger {
  background: var(--danger);
  color: white;
}
.btn-danger:hover { background: #dc2626; }

.btn-sm {
  padding: 6px 12px;
  font-size: 13px;
  border-radius: 6px;
}

.btn-lg {
  padding: 14px 28px;
  font-size: 16px;
  border-radius: 10px;
}

.btn-block { width: 100%; }

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

/* Social login buttons */
.btn-qq {
  background: #12b7f5;
  color: white;
}
.btn-qq:hover { background: #0ea5e0; }

.btn-github {
  background: #24292e;
  color: white;
}
.btn-github:hover { background: #1a1f24; }

.btn-wechat {
  background: #07c160;
  color: white;
}
.btn-wechat:hover { background: #06ad56; }

/* ========== Forms ========== */
.form-group { margin-bottom: 16px; }

.form-label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  margin-bottom: 6px;
  color: var(--text);
}

.form-input {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  transition: border 0.2s, box-shadow 0.2s;
  outline: none;
}

.form-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79,70,229,0.1);
}

.form-input.error { border-color: var(--danger); }

.form-error {
  font-size: 13px;
  color: var(--danger);
  margin-top: 4px;
}

/* ========== Login Page ========== */
.login-container {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.login-card {
  background: var(--card);
  border-radius: 16px;
  box-shadow: var(--shadow-lg);
  padding: 40px;
  width: 100%;
  max-width: 420px;
  border: 1px solid var(--border);
}

.login-card .logo-section {
  text-align: center;
  margin-bottom: 32px;
}

.login-card .logo-section h1 {
  font-size: 28px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 8px;
}

.login-card .logo-section p {
  color: var(--text-muted);
  font-size: 14px;
}

.divider {
  display: flex;
  align-items: center;
  gap: 16px;
  margin: 24px 0;
  color: var(--text-muted);
  font-size: 13px;
}

.divider::before, .divider::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

.social-buttons {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.verify-code-row {
  display: flex;
  gap: 12px;
}

.verify-code-row .form-input {
  flex: 1;
}

.send-code-btn {
  white-space: nowrap;
  min-width: 120px;
}

/* ========== Toast ========== */
.toast-container {
  position: fixed;
  top: 20px;
  right: 20px;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.toast {
  padding: 12px 20px;
  border-radius: 8px;
  font-size: 14px;
  color: white;
  box-shadow: var(--shadow-lg);
  animation: slideIn 0.3s ease;
  max-width: 360px;
}

.toast-success { background: var(--success); }
.toast-error { background: var(--danger); }
.toast-info { background: var(--primary); }

@keyframes slideIn {
  from { transform: translateX(100%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

/* ========== Dashboard ========== */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
  margin-top: 20px;
}

.tool-card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
  border: 1px solid var(--border);
  cursor: pointer;
  transition: all 0.2s;
}

.tool-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.tool-card .tool-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  background: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  margin-bottom: 16px;
}

.tool-card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
}

.tool-card p {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.5;
}

/* Chat panel */
.chat-panel {
  display: flex;
  flex-direction: column;
  height: calc(100vh - 180px);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--card);
}

.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.chat-msg {
  max-width: 80%;
  padding: 12px 16px;
  border-radius: 12px;
  font-size: 14px;
  line-height: 1.6;
  white-space: pre-wrap;
}

.chat-msg.user {
  align-self: flex-end;
  background: var(--primary);
  color: white;
}

.chat-msg.ai {
  align-self: flex-start;
  background: var(--bg);
  border: 1px solid var(--border);
}

.chat-input-area {
  display: flex;
  gap: 12px;
  padding: 16px 20px;
  border-top: 1px solid var(--border);
  background: var(--card);
}

.chat-input-area textarea {
  flex: 1;
  resize: none;
  min-height: 44px;
  max-height: 120px;
}

/* ========== Community ========== */
.community-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
  flex-wrap: wrap;
  gap: 12px;
}

.post-card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
  border: 1px solid var(--border);
  margin-bottom: 16px;
}

.post-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 12px;
}

.post-header .avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
}

.post-meta { font-size: 13px; color: var(--text-muted); }

.post-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 8px;
}

.post-content {
  font-size: 14px;
  color: var(--text);
  line-height: 1.7;
  margin-bottom: 16px;
}

.post-tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

.tag {
  padding: 4px 10px;
  background: var(--primary-light);
  color: var(--primary);
  border-radius: 20px;
  font-size: 12px;
  font-weight: 500;
}

.post-actions {
  display: flex;
  gap: 16px;
  align-items: center;
}

.post-actions button {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 13px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 4px 8px;
  border-radius: 6px;
  transition: all 0.2s;
}

.post-actions button:hover { background: var(--bg); color: var(--primary); }

/* Comments */
.comments-section {
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

.comment {
  padding: 10px 0;
  border-bottom: 1px solid var(--border);
}

.comment:last-child { border-bottom: none; }

.comment .comment-author {
  font-weight: 600;
  font-size: 13px;
  margin-bottom: 4px;
}

.comment .comment-text {
  font-size: 14px;
  color: var(--text);
}

.comment .comment-time {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 4px;
}

/* ========== Admin ========== */
.admin-tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 24px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0;
}

.admin-tabs button {
  padding: 10px 20px;
  background: none;
  border: none;
  font-size: 14px;
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.2s;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
}

.admin-tabs button.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  font-weight: 600;
}

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

.user-table {
  width: 100%;
  border-collapse: collapse;
}

.user-table th, .user-table td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border);
  font-size: 14px;
}

.user-table th {
  font-weight: 600;
  color: var(--text-muted);
  font-size: 13px;
}

.user-table tr:hover { background: var(--bg); }

.badge {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 500;
}

.badge-success { background: #d1fae5; color: #065f46; }
.badge-danger { background: #fee2e2; color: #991b1b; }
.badge-warning { background: #fef3c7; color: #92400e; }

/* ========== Modal ========== */
.modal-overlay {
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(0,0,0,0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 24px;
}

.modal {
  background: var(--card);
  border-radius: 16px;
  padding: 32px;
  max-width: 500px;
  width: 100%;
  box-shadow: var(--shadow-lg);
}

.modal h2 { margin-bottom: 20px; font-size: 20px; }

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
  margin-top: 24px;
}

/* ========== Loading ========== */
.spinner {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
  display: inline-block;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ========== Utility ========== */
.hidden { display: none !important; }
.text-center { text-align: center; }
.text-muted { color: var(--text-muted); }
.mt-4 { margin-top: 16px; }
.mt-8 { margin-top: 32px; }
.mb-4 { margin-bottom: 16px; }
.mb-8 { margin-bottom: 32px; }
.flex { display: flex; }
.gap-2 { gap: 8px; }
.gap-4 { gap: 16px; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }

/* OAuth Callback banner */
.oauth-banner {
  padding: 16px;
  border-radius: 8px;
  text-align: center;
  margin-bottom: 16px;
}

.oauth-banner.loading {
  background: var(--primary-light);
  color: var(--primary);
}

.oauth-banner.error {
  background: #fee2e2;
  color: var(--danger);
}

/* ========== Responsive ========== */
@media (max-width: 768px) {
  .container { padding: 16px; }
  .login-card { padding: 24px; }
  .tools-grid { grid-template-columns: 1fr; }
  .navbar { padding: 0 16px; }
  .user-table { display: block; overflow-x: auto; }
}