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

body {
    font-family: 'Noto Sans', sans-serif;
    background: #f5f5f5;
    color: #1a1a1a;
    padding: 0;
    min-height: 100vh;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background: #fff;
    min-height: 100vh;
}

.lesson-header {
    background: linear-gradient(135deg, #2c3e50 0%, #3498db 100%);
    color: #fff;
    padding: 32px 24px;
    border-bottom: 4px solid #2980b9;
}

.lesson-number {
    font-size: 12px;
    font-weight: 600;
    letter-spacing: 1px;
    text-transform: uppercase;
    opacity: 0.9;
    margin-bottom: 8px;
}

.lesson-title {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 8px;
}

.lesson-subtitle {
    font-size: 14px;
    opacity: 0.85;
}

.lesson-content {
    padding: 24px;
}

.section {
    margin-bottom: 32px;
    padding-bottom: 32px;
    border-bottom: 1px solid #e0e0e0;
}

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

.section-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.step-badge {
    background: #3498db;
    color: #fff;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

.section-title {
    font-size: 18px;
    font-weight: 700;
    color: #2c3e50;
}

.instruction {
    font-size: 14px;
    color: #555;
    margin-bottom: 20px;
    line-height: 1.6;
}

.scenario-selector {
    font-family: 'Noto Sans', sans-serif;
    font-size: 14px;
    padding: 12px 16px;
    background: #fff;
    color: #333;
    border: 2px solid #ddd;
    border-radius: 6px;
    cursor: pointer;
    width: 100%;
    margin-bottom: 16px;
    transition: border-color 0.2s;
}

.scenario-selector:focus {
    outline: none;
    border-color: #3498db;
}

.scenario-box {
    background: #f8f9fa;
    border-left: 4px solid #3498db;
    padding: 16px 20px;
    border-radius: 4px;
}

.scenario-label {
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: #3498db;
    margin-bottom: 8px;
}

.scenario-text {
    font-size: 15px;
    line-height: 1.7;
    color: #2c3e50;
}

.thinking-areas {
    display: grid;
    grid-template-columns: 1fr;
    gap: 20px;
}

.area {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.area-header {
    display: flex;
    align-items: center;
    gap: 10px;
}

.area-number {
    width: 24px;
    height: 24px;
    background: #ecf0f1;
    color: #2c3e50;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    font-weight: 700;
    flex-shrink: 0;
}

.area-label {
    font-size: 13px;
    font-weight: 600;
    color: #2c3e50;
}

textarea {
    font-family: 'Noto Sans', sans-serif;
    font-size: 14px;
    padding: 14px;
    border: 2px solid #e0e0e0;
    border-radius: 6px;
    resize: vertical;
    min-height: 90px;
    transition: border-color 0.2s, box-shadow 0.2s;
    background: #fafafa;
}

textarea:focus {
    outline: none;
    border-color: #3498db;
    background: #fff;
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
}

.btn {
    padding: 14px 24px;
    font-family: 'Noto Sans', sans-serif;
    font-size: 14px;
    font-weight: 600;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: transform 0.1s, box-shadow 0.2s;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.btn:active {
    transform: translateY(1px);
}

.btn-reveal {
    background: #3498db;
    color: #fff;
    width: 100%;
    margin-bottom: 20px;
    box-shadow: 0 2px 8px rgba(52, 152, 219, 0.3);
}

.btn-reveal:hover {
    box-shadow: 0 4px 12px rgba(52, 152, 219, 0.4);
}

.btn-icon {
    font-size: 16px;
}

.btn-arrow {
    font-size: 16px;
}

.hints {
    display: none;
    flex-direction: column;
    gap: 16px;
    padding: 20px;
    background: #f0f8ff;
    border-radius: 8px;
    border: 2px solid #d0e8ff;
}

.hints.visible {
    display: flex;
}

.hint-section {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.hint-title {
    font-size: 12px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: #2980b9;
}

.hint-content {
    font-size: 14px;
    line-height: 1.6;
    color: #2c3e50;
    padding-left: 12px;
    border-left: 3px solid #3498db;
}

.lesson-nav {
    padding: 24px;
    background: #f8f9fa;
    border-top: 1px solid #e0e0e0;
}

.btn-next {
    background: #2c3e50;
    color: #fff;
    width: 100%;
    box-shadow: 0 2px 8px rgba(44, 62, 80, 0.3);
}

.btn-next:hover {
    box-shadow: 0 4px 12px rgba(44, 62, 80, 0.4);
}

@media (min-width: 640px) {
    .lesson-header {
        padding: 40px 32px;
    }

    .lesson-content {
        padding: 32px;
    }

    .lesson-title {
        font-size: 28px;
    }

    .thinking-areas {
        grid-template-columns: 1fr 1fr;
    }

    .lesson-nav {
        padding: 24px 32px;
    }
}