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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background-color: #f8f9fc;
    color: #333;
}

/* Navbar */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 60px;
    background: #fff;
    box-shadow: 0 1px 8px rgba(0,0,0,0.07);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-brand {
    font-size: 22px;
    font-weight: 700;
    color: #007bff;
}

.nav-cta {
    background-color: #007bff;
    color: #fff;
    padding: 10px 24px;
    border-radius: 24px;
    text-decoration: none;
    font-weight: 600;
    font-size: 15px;
    transition: background-color 0.2s;
}

.nav-cta:hover {
    background-color: #0056b3;
}

/* Hero */
.hero {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 100px 60px;
    background: linear-gradient(135deg, #e8f0fe 0%, #f0f4ff 100%);
    gap: 60px;
}

.hero-content {
    max-width: 520px;
}

.hero-content h1 {
    font-size: 52px;
    font-weight: 800;
    color: #1a1a2e;
    line-height: 1.2;
    margin-bottom: 20px;
}

.hero-content p {
    font-size: 18px;
    color: #555;
    line-height: 1.7;
    margin-bottom: 36px;
}

.btn-primary {
    display: inline-block;
    background-color: #007bff;
    color: #fff;
    padding: 16px 36px;
    border-radius: 30px;
    text-decoration: none;
    font-size: 17px;
    font-weight: 700;
    transition: background-color 0.2s, transform 0.2s;
}

.btn-primary:hover {
    background-color: #0056b3;
    transform: translateY(-2px);
}

/* Hero Visual */
.hero-visual {
    display: flex;
    flex-direction: column;
    gap: 14px;
    min-width: 280px;
}

.bubble {
    padding: 14px 20px;
    border-radius: 20px;
    font-size: 15px;
    max-width: 260px;
    line-height: 1.5;
    animation: fadeInUp 0.5s ease both;
}

.bubble-bot {
    background: #fff;
    color: #333;
    align-self: flex-start;
    border-bottom-left-radius: 4px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.08);
    animation-delay: 0.2s;
}

.bubble-user {
    background: #007bff;
    color: #fff;
    align-self: flex-end;
    border-bottom-right-radius: 4px;
    animation-delay: 0.4s;
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(16px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* Features */
.features {
    padding: 100px 60px;
    text-align: center;
    background: #fff;
}

.features h2 {
    font-size: 36px;
    font-weight: 800;
    color: #1a1a2e;
    margin-bottom: 60px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 30px;
    max-width: 1100px;
    margin: 0 auto;
}

.feature-card {
    background: #f8f9fc;
    border-radius: 16px;
    padding: 36px 24px;
    transition: transform 0.2s, box-shadow 0.2s;
}

.feature-card:hover {
    transform: translateY(-6px);
    box-shadow: 0 12px 30px rgba(0,0,0,0.08);
}

.feature-icon {
    font-size: 40px;
    margin-bottom: 16px;
}

.feature-card h3 {
    font-size: 18px;
    font-weight: 700;
    margin-bottom: 10px;
    color: #1a1a2e;
}

.feature-card p {
    font-size: 14px;
    color: #666;
    line-height: 1.6;
}

/* Chat Section */
.chat-section {
    padding: 100px 60px;
    text-align: center;
    background: linear-gradient(135deg, #f0f4ff 0%, #e8f0fe 100%);
}

.chat-section h2 {
    font-size: 36px;
    font-weight: 800;
    color: #1a1a2e;
    margin-bottom: 12px;
}

.chat-subtitle {
    font-size: 16px;
    color: #666;
    margin-bottom: 40px;
}

#chat-container {
    width: 480px;
    height: 520px;
    border-radius: 16px;
    background-color: #fff;
    display: flex;
    flex-direction: column;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
    margin: 0 auto;
}

#chat-messages {
    flex-grow: 1;
    overflow-y: auto;
    padding: 24px;
    display: flex;
    flex-direction: column;
    gap: 14px;
}

.message {
    padding: 12px 18px;
    border-radius: 18px;
    max-width: 75%;
    word-wrap: break-word;
    font-size: 15px;
    line-height: 1.5;
}

.user-message {
    background-color: #007bff;
    color: white;
    align-self: flex-end;
    border-bottom-right-radius: 4px;
}

.bot-message {
    background-color: #f0f2f5;
    color: #333;
    align-self: flex-start;
    border-bottom-left-radius: 4px;
}

#chat-input-container {
    display: flex;
    padding: 16px 20px;
    border-top: 1px solid #eee;
    gap: 10px;
}

#chat-input {
    flex-grow: 1;
    border: 1px solid #ddd;
    border-radius: 24px;
    padding: 12px 18px;
    font-size: 15px;
    outline: none;
    transition: border-color 0.2s;
}

#chat-input:focus {
    border-color: #007bff;
}

#send-button {
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 24px;
    padding: 12px 22px;
    cursor: pointer;
    font-size: 15px;
    font-weight: 600;
    transition: background-color 0.2s;
    white-space: nowrap;
}

#send-button:hover {
    background-color: #0056b3;
}

/* Footer */
.footer {
    text-align: center;
    padding: 30px;
    background: #1a1a2e;
    color: #aaa;
    font-size: 14px;
}

/* Responsive */
@media (max-width: 900px) {
    .navbar { padding: 16px 24px; }
    .hero { flex-direction: column; padding: 60px 24px; text-align: center; }
    .hero-content h1 { font-size: 36px; }
    .hero-visual { align-items: center; }
    .features { padding: 60px 24px; }
    .features-grid { grid-template-columns: repeat(2, 1fr); }
    .chat-section { padding: 60px 24px; }
    #chat-container { width: 100%; }
}

@media (max-width: 500px) {
    .features-grid { grid-template-columns: 1fr; }
    .hero-content h1 { font-size: 28px; }
}