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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: #333;
    background: #fff;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 120px 0;
    text-align: center;
}

.hero h1 {
    font-size: 5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    letter-spacing: -2px;
}

.tagline {
    font-size: 1.8rem;
    margin-bottom: 0.5rem;
    opacity: 0.95;
}

.subtitle {
    font-size: 1.3rem;
    opacity: 0.9;
    font-weight: 300;
}

/* Problem & Solution */
.problem-solution {
    padding: 80px 0;
    text-align: center;
    background: #f8f9fa;
}

.problem h2 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    line-height: 1.3;
}

.solution p {
    font-size: 1.3rem;
    color: #555;
    max-width: 700px;
    margin: 0 auto;
    line-height: 1.6;
}

/* Demo Section */
.demo {
    padding: 80px 0;
}

.demo h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 4rem;
}

/* Step Sections */
.step-section {
    margin-bottom: 4rem;
}

.step-header {
    text-align: center;
    margin-bottom: 2rem;
}

.step-number {
    display: inline-block;
    background: #667eea;
    color: white;
    padding: 8px 20px;
    border-radius: 25px;
    font-weight: bold;
    font-size: 0.9rem;
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.step-header h3 {
    font-size: 1.8rem;
    margin: 0;
}

/* Step 1: Scenario Card */
.scenario-card {
    background: #f8f9fa;
    border-radius: 15px;
    padding: 2rem;
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.scenario-meta {
    display: flex;
    justify-content: space-between;
    margin-bottom: 1rem;
}

.scenario-count {
    color: #666;
    font-size: 0.9rem;
}

.level-badge {
    background: #667eea;
    color: white;
    padding: 0.2rem 0.8rem;
    border-radius: 20px;
    font-size: 0.9rem;
}

.scenario-card h4 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.scenario-card p {
    color: #666;
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.action-button {
    background: #667eea;
    color: white;
    border: none;
    padding: 12px 30px;
    border-radius: 25px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s;
    margin-right: 1rem;
}

.action-button:hover {
    background: #5a67d8;
    transform: translateY(-2px);
}

.action-button.secondary {
    background: white;
    color: #667eea;
    border: 2px solid #667eea;
}

.action-button.secondary:hover {
    background: #f0f0ff;
}

/* Chat Interface */
.chat-interface {
    background: #fff;
    border: 1px solid #e0e0e0;
    border-radius: 15px;
    overflow: hidden;
    margin-bottom: 2rem;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.chat-header {
    background: #f8f9fa;
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid #e0e0e0;
}

.chat-header span:first-child {
    font-weight: 600;
}

.timer {
    color: #666;
    font-size: 0.9rem;
}

.messages {
    padding: 1.5rem;
    min-height: 350px;
    max-height: 450px;
    overflow-y: auto;
    background: #fafafa;
}

.message {
    margin-bottom: 1rem;
    display: flex;
}

.message.ai {
    justify-content: flex-start;
}

.message.user {
    justify-content: flex-end;
}

.message-bubble {
    max-width: 70%;
    padding: 0.8rem 1.2rem;
    border-radius: 18px;
    font-size: 1rem;
}

.ai .message-bubble {
    background: #e3e3e3;
    color: #333;
}

.user .message-bubble {
    background: #667eea;
    color: white;
}

.chat-input {
    padding: 1rem 1.5rem;
    background: white;
    border-top: 1px solid #e0e0e0;
}

.voice-button {
    width: 100%;
    padding: 12px;
    background: #f0f0f0;
    border: 2px solid #ddd;
    border-radius: 25px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s;
}

.voice-button:hover {
    background: #e0e0e0;
}

/* Step 3: Corrections */
.corrections-container {
    max-width: 800px;
    margin: 0 auto;
}

.correction {
    background: white;
    border: 1px solid #e0e0e0;
    border-radius: 10px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.your-version, .native-version {
    margin-bottom: 1rem;
}

.label {
    font-size: 0.9rem;
    color: #666;
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.your-version p {
    color: #333;
    font-size: 1.1rem;
    background: #ffe5e5;
    padding: 0.8rem 1rem;
    border-radius: 8px;
    display: inline-block;
}

.native-version p:first-of-type {
    color: #333;
    font-size: 1.1rem;
    background: #e5ffe5;
    padding: 0.8rem 1rem;
    border-radius: 8px;
    display: inline-block;
    margin-bottom: 0.8rem;
}

.explanation-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.explanation-list li {
    font-size: 0.9rem;
    color: #666;
    padding-left: 1.5rem;
    position: relative;
    margin-bottom: 0.5rem;
}

.explanation-list li:before {
    content: "✓";
    position: absolute;
    left: 0;
    color: #4ade80;
    font-weight: bold;
}

/* Step 4: Practice Interface */
.practice-interface {
    max-width: 800px;
    margin: 0 auto;
}

.practice-intro {
    font-size: 1.1rem;
    text-align: center;
    margin-bottom: 2rem;
    color: #555;
}

.chat-interface.practice-mode {
    border: 2px solid #4ade80;
}

.practice-badge {
    background: #4ade80;
    color: white;
    padding: 0.3rem 0.8rem;
    border-radius: 15px;
    font-size: 0.85rem;
    font-weight: 600;
}

.message.user.improved {
    position: relative;
}

.improvement-indicator {
    position: absolute;
    bottom: -20px;
    right: 0;
    font-size: 0.85rem;
    color: #4ade80;
    font-weight: 600;
}

.voice-button.practice {
    background: #4ade80;
    border-color: #4ade80;
    color: white;
}

.voice-button.practice:hover {
    background: #22c55e;
}

.practice-complete {
    text-align: center;
    margin-top: 2rem;
    padding: 2rem;
    background: #f0fdf4;
    border-radius: 10px;
}

.practice-complete p {
    font-size: 1.2rem;
    color: #16a34a;
    margin-bottom: 1.5rem;
}

.action-button.primary {
    background: #667eea;
    color: white;
    margin-bottom: 0.5rem;
}

/* Waitlist Section */
.waitlist {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 80px 0;
    text-align: center;
}

.waitlist h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.waitlist p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.waitlist-form {
    display: flex;
    gap: 1rem;
    max-width: 450px;
    margin: 0 auto;
}

.waitlist-form input {
    flex: 1;
    padding: 15px 20px;
    border: none;
    border-radius: 50px;
    font-size: 1rem;
}

.waitlist-form button {
    background: #333;
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 50px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.3s;
    white-space: nowrap;
}

.waitlist-form button:hover {
    background: #222;
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 3.5rem;
    }
    
    .tagline {
        font-size: 1.5rem;
    }
    
    .subtitle {
        font-size: 1.1rem;
    }
    
    .problem h2, .demo h2, .waitlist h2 {
        font-size: 2rem;
    }
    
    .solution p {
        font-size: 1.1rem;
    }
    
    .waitlist-form {
        flex-direction: column;
    }
    
    .waitlist-form button {
        width: 100%;
    }
    
    .message-bubble {
        max-width: 85%;
    }
    
    .action-button {
        display: block;
        width: 100%;
        margin-right: 0;
        margin-bottom: 0.5rem;
    }
    
    .step-header {
        flex-wrap: wrap;
    }
}