:root {
   --primary: #2563eb;
   --primary-dark: #1d4ed8;
   --secondary: #10b981;
   --danger: #ef4444;
   --white: #ffffff;
   --bg-card: #ffffff;
   --bg-light: #f8fafc;
   --text-primary: #1e293b;
   --text-secondary: #64748b;
   --border-color: #e2e8f0;
   --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
   --radius: 8px;
}

.hero-rbt {
   padding: 4rem 0;
   text-align: center;
   border-bottom: 1px solid var(--border-color);
   box-shadow: var(--shadow);
   background: linear-gradient(135deg, #ffffff, #fcfdff);
}

.hero-rbt h1 {
   font-size: 2.2rem;
   margin-bottom: 1.5rem;
   color: var(--text-primary);
}

.hero-rbt p {
   font-size: 1.1rem;
   max-width: 800px;
   margin: 0 auto 2rem;
   color: var(--text-secondary);
}

.generator {
   background: var(--white);
   border-radius: var(--radius);
   padding: 2.5rem;
   margin: 3rem 0;
   box-shadow: var(--shadow);
}

.generator h2 {
   font-size: 2rem;
   margin-bottom: 1.5rem;
   color: var(--primary);
   text-align: center;
}

.form-group {
   margin-bottom: 1.5rem;
}

.form-group label {
   display: block;
   margin-bottom: 0.5rem;
   font-weight: 600;
   color: var(--text-primary);
}

.form-control {
   width: 100%;
   padding: 0.75rem 1rem;
   border: 1px solid #d1d5db;
   border-radius: var(--radius);
   font-size: 1rem;
   transition: border-color 0.3s, box-shadow 0.3s;
}

.form-control:focus {
   outline: none;
   border-color: var(--primary);
   box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.2);
}

.char-counter {
   margin-top: 0.5rem;
   font-size: 0.9rem;
   color: var(--text-secondary);
}

.char-count {
   font-weight: 600;
   color: var(--text-primary);
}

.char-status.ok {
   color: var(--secondary);
}

.char-status.warn {
   color: #f59e0b;
}

.char-status.over {
   color: var(--danger);
}

.tips {
   background: #eff6ff;
   border-left: 4px solid var(--primary);
   padding: 1rem 1.5rem;
   margin: 2rem 0;
   border-radius: 0 var(--radius) var(--radius) 0;
}

.tips h3 {
   color: var(--primary);
   margin-bottom: 0.5rem;
}

.tips ul {
   padding-left: 1.5rem;
}

.tips li {
   margin-bottom: 0.5rem;
}

.btn {
   display: inline-block;
   padding: 0.75rem 1.5rem;
   background: var(--primary);
   color: var(--white);
   border: none;
   border-radius: var(--radius);
   font-size: 1rem;
   font-weight: 600;
   cursor: pointer;
   transition: background-color 0.3s, transform 0.2s;
   text-decoration: none;
}

.btn-secondary {
   background: var(--secondary);
}

.btn-secondary:hover {
   background: #059669;
   transform: translateY(-2px);
}

.btn-danger {
   background: var(--danger);
}

.btn-danger:hover {
   background: #dc2626;
   transform: translateY(-2px);
}

.btn-group {
   display: flex;
   gap: 10px;
   margin-top: 1.5rem;
}

.serp-preview-wrapper {
   margin-top: 2.5rem;
   padding: 1.5rem;
   background: var(--bg-light);
   border-radius: var(--radius);
   border: 1px solid var(--border-color);
}

.serp-preview-wrapper h3 {
   font-size: 1.2rem;
   margin-bottom: 0.5rem;
   color: var(--primary);
}

.serp-preview-wrapper h3 i {
   margin-right: 0.5rem;
}

.preview-hint {
   font-size: 0.9rem;
   color: var(--text-secondary);
   margin-bottom: 1rem;
}

.serp-preview {
   padding: 1.25rem 1.5rem;
   background: var(--white);
   border-radius: var(--radius);
   box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
   font-family: arial, sans-serif;
   max-width: 600px;
}

.serp-preview-url {
   font-size: 0.875rem;
   color: #202124;
   margin-bottom: 0.25rem;
   line-height: 1.3;
}

.serp-preview-title {
   font-size: 1.25rem;
   color: #1a0dab;
   line-height: 1.3;
   margin-bottom: 0.25rem;
   cursor: pointer;
}

.serp-preview-title:hover {
   text-decoration: underline;
}

.serp-preview-title.truncated {
   color: #1a0dab;
}

.serp-preview-desc {
   font-size: 0.875rem;
   color: #4d5156;
   line-height: 1.57;
}

.serp-preview-desc.truncated {
   color: #4d5156;
}

.features {
   display: grid;
   grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
   gap: 2rem;
   margin: 3rem 0;
}

.feature-card {
   background: var(--white);
   border-radius: var(--radius);
   padding: 2rem;
   box-shadow: var(--shadow);
   transition: transform 0.3s, box-shadow 0.3s;
}

.feature-card:hover {
   transform: translateY(-5px);
   box-shadow: 0 10px 15px rgba(0, 0, 0, 0.1);
}

.feature-card i {
   font-size: 2.5rem;
   color: var(--primary);
   margin-bottom: 1rem;
}

.feature-card h3 {
   font-size: 1.4rem;
   margin-bottom: 1rem;
   color: var(--text-primary);
}

.info-section {
   width: 100%;
   padding: 3rem 0;
}

.section-title {
   font-size: 2rem;
   font-weight: 700;
   margin-bottom: 2rem;
   color: var(--text-primary);
   text-align: center;
}

.how-to-steps {
   display: grid;
   grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
   gap: 2rem;
   margin-top: 2rem;
}

.step-card {
   background: var(--white);
   border-radius: var(--radius);
   padding: 1.5rem;
   box-shadow: var(--shadow);
   position: relative;
}

.step-number {
   position: absolute;
   top: -15px;
   left: -15px;
   width: 40px;
   height: 40px;
   background: var(--primary);
   color: var(--white);
   border-radius: 50%;
   display: flex;
   align-items: center;
   justify-content: center;
   font-weight: bold;
   font-size: 1.2rem;
}

.step-card h3 {
   margin: 0.5rem 0 1rem;
   color: var(--text-primary);
}

.faq-container-rbt {
   margin-top: 2rem;
}

.faq-container-rbt .faq-item {
   background: var(--white);
   border-radius: var(--radius);
   margin-bottom: 1rem;
   box-shadow: var(--shadow);
   overflow: hidden;
}

.faq-container-rbt .faq-question {
   padding: 1rem 1.5rem;
   cursor: pointer;
   display: flex;
   justify-content: space-between;
   align-items: center;
   font-weight: 600;
   color: var(--text-primary);
}

.faq-container-rbt .faq-question i {
   transition: transform 0.3s;
}

.faq-container-rbt .faq-item.active .faq-question i {
   transform: rotate(180deg);
}

.faq-container-rbt .faq-answer {
   max-height: 0;
   overflow: hidden;
   transition: max-height 0.3s ease;
}

.faq-container-rbt .faq-item.active .faq-answer {
   max-height: 300px;
}

.faq-container-rbt .faq-answer p {
   padding: 0 1.5rem 1.5rem;
   margin: 0;
   color: var(--text-secondary);
}

@media (max-width: 768px) {
   .btn-group {
      flex-direction: column;
   }
}