* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: #333;
  background: #f5f6f8;
  font-size: 15px;
  line-height: 1.7;
}

a {
  color: #4a6cf7;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 24px;
}

.navbar {
  background: #fff;
  border-bottom: 1px solid #e5e7eb;
  padding: 10px 0;
  display: flex;
  align-items: center;
}

.navbar .container {
  display: flex;
  align-items: center;
  gap: 18px;
  flex-wrap: wrap;
}

.navbar .brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  font-size: 16px;
  color: #333;
}

.navbar .brand img {
  height: 32px;
}

.navbar .links {
  display: flex;
  gap: 14px;
  flex: 1;
}

.navbar .user-box {
  display: flex;
  align-items: center;
  gap: 8px;
}

.navbar .user-box img {
  height: 28px;
  width: 28px;
  border-radius: 50%;
  object-fit: cover;
}

.card {
  background: #fff;
  border: 1px solid #e5e7eb;
  border-radius: 8px;
  padding: 24px;
  margin: 20px 0;
}

.page-title {
  font-size: 20px;
  font-weight: 600;
  margin: 20px 0 12px;
}

.btn {
  display: inline-block;
  padding: 7px 14px;
  border: 1px solid #d1d5db;
  border-radius: 6px;
  background: #fff;
  color: #333;
  cursor: pointer;
  font-size: 14px;
}

.btn:hover {
  background: #f3f4f6;
  text-decoration: none;
}

.btn-primary {
  background: #4a6cf7;
  border-color: #4a6cf7;
  color: #fff;
}

.btn-primary:hover {
  background: #3a5bd9;
  color: #fff;
}

.btn-danger {
  background: #e11d48;
  border-color: #e11d48;
  color: #fff;
}

.btn-danger:hover {
  background: #be123c;
  color: #fff;
}

.btn.confirming {
  box-shadow: 0 0 0 3px rgba(225, 29, 72, 0.35);
  animation: confirmPulse 0.9s ease-in-out infinite;
}

@keyframes confirmPulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.06); }
}

.btn-sm {
  padding: 3px 9px;
  font-size: 12px;
}

.action-group {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: nowrap;
  white-space: nowrap;
}

input[type="text"],
input[type="password"],
input[type="email"],
select,
textarea {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid #d1d5db;
  border-radius: 6px;
  font-size: 14px;
  margin-bottom: 10px;
}

label {
  display: block;
  font-weight: 500;
  margin-bottom: 4px;
}

.flash {
  padding: 10px 14px;
  border-radius: 6px;
  margin: 10px 0;
}

.flash.success {
  background: #ecfdf5;
  color: #047857;
  border: 1px solid #a7f3d0;
}

.flash.danger {
  background: #fef2f2;
  color: #b91c1c;
  border: 1px solid #fecaca;
}

.flash.warning {
  background: #fffbeb;
  color: #b45309;
  border: 1px solid #fde68a;
}

table {
  width: 100%;
  border-collapse: collapse;
  background: #fff;
}

th,
td {
  padding: 12px 16px;
  border-bottom: 1px solid #e5e7eb;
  text-align: left;
  vertical-align: top;
}

th {
  background: #f9fafb;
  font-weight: 600;
}

.form-row {
  display: flex;
  gap: 10px;
  align-items: flex-end;
  flex-wrap: wrap;
}

.form-row > div {
  flex: 1;
  min-width: 140px;
}

.message {
  padding: 16px 18px;
  border-radius: 8px;
  margin: 12px 0;
}

.message.user {
  background: #eef2ff;
  border: 1px solid #c7d2fe;
}

.message.assistant {
  background: #f9fafb;
  border: 1px solid #e5e7eb;
}

.markdown-body {
  line-height: 1.6;
  word-wrap: break-word;
}

.markdown-body > :first-child {
  margin-top: 0;
}

.markdown-body > :last-child {
  margin-bottom: 0;
}

.markdown-body p {
  margin: 0 0 8px;
}

.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4,
.markdown-body h5,
.markdown-body h6 {
  margin: 12px 0 6px;
  line-height: 1.3;
}

.markdown-body ul,
.markdown-body ol {
  margin: 0 0 8px;
  padding-left: 22px;
}

.markdown-body li {
  margin: 2px 0;
}

.markdown-body pre {
  background: #f3f4f6;
  border: 1px solid #e5e7eb;
  border-radius: 6px;
  padding: 10px 12px;
  overflow-x: auto;
  margin: 0 0 8px;
}

.markdown-body code {
  font-family: Consolas, Menlo, monospace;
  font-size: 13px;
}

.markdown-body pre code {
  padding: 0;
  background: transparent;
}

.markdown-body :not(pre) > code {
  background: #f3f4f6;
  border-radius: 4px;
  padding: 1px 5px;
}

.markdown-body blockquote {
  margin: 0 0 8px;
  padding: 2px 12px;
  border-left: 3px solid #d1d5db;
  color: #6b7280;
}

.markdown-body table {
  border-collapse: collapse;
  margin: 0 0 8px;
}

.markdown-body table th,
.markdown-body table td {
  border: 1px solid #e5e7eb;
  padding: 6px 10px;
}

.markdown-body hr {
  border: 0;
  border-top: 1px solid #e5e7eb;
  margin: 12px 0;
}

.message .role {
  font-weight: 600;
  font-size: 12px;
  color: #6b7280;
  margin-bottom: 4px;
  white-space: nowrap;
}

.thumb {
  width: 90px;
  height: 90px;
  object-fit: cover;
  border: 1px solid #e5e7eb;
  border-radius: 6px;
  margin: 4px;
}

.thumb-row {
  display: flex;
  flex-wrap: wrap;
}

.auth-form {
  max-width: 420px;
  margin: 40px auto;
}

.center {
  text-align: center;
}

.muted {
  color: #6b7280;
  font-size: 12px;
}

.badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 10px;
  font-size: 12px;
}

.badge.on {
  background: #ecfdf5;
  color: #047857;
}

.badge.off {
  background: #fef2f2;
  color: #b91c1c;
}

.badge.not-mastered {
  background: #fef2f2;
  color: #b91c1c;
}

.badge.mastered {
  background: #ecfdf5;
  color: #047857;
}

.divider {
  border: 0;
  border-top: 1px solid #e5e7eb;
  margin: 16px 0;
}

.loading-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
}

.loading-box {
  background: #fff;
  padding: 28px 36px;
  border-radius: 10px;
  text-align: center;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.2);
}

.spinner {
  width: 36px;
  height: 36px;
  border: 4px solid #e5e7eb;
  border-top-color: #4a6cf7;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: 0 auto 12px;
}

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

.loading-text {
  color: #555;
  font-size: 14px;
}

.hero {
  text-align: center;
  padding: 56px 20px 48px;
}

.hero h1 {
  font-size: 34px;
  margin: 0 0 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
}

.hero-logo {
  height: 52px;
}

.hero-tagline {
  font-size: 18px;
  color: #4a6cf7;
  margin: 0 0 10px;
  font-weight: 600;
}

.hero-desc {
  color: #6b7280;
  max-width: 620px;
  margin: 0 auto 24px;
}

.hero-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn-lg {
  padding: 11px 28px;
  font-size: 16px;
}

.section-title {
  font-size: 20px;
  margin: 0 0 16px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
}

.feature {
  border: 1px solid #e5e7eb;
  border-radius: 8px;
  padding: 16px;
  background: #f9fafb;
}

.feature h3 {
  margin: 0 0 6px;
  font-size: 16px;
  color: #333;
}

.feature p {
  margin: 0;
  color: #6b7280;
  font-size: 14px;
}

.steps {
  margin: 0;
  padding-left: 22px;
}

.steps li {
  margin: 0 0 14px;
}

.steps li p {
  margin: 2px 0 0;
  color: #6b7280;
}