/* 기본 스타일 초기화 및 전역 설정 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Noto Sans KR', sans-serif;
    line-height: 1.6;
    color: #333;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 헤더 스타일 */
.header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
    padding: 20px 0;
    margin-bottom: 30px;
}

/* 네비게이션 */
.navigation {
    text-align: right;
    margin-bottom: 15px;
}

.nav-link {
    color: #3498db;
    text-decoration: none;
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    padding: 8px 15px;
    border-radius: 20px;
    background: rgba(52, 152, 219, 0.1);
    transition: all 0.3s ease;
}

.nav-link:hover {
    background: rgba(52, 152, 219, 0.2);
    transform: translateY(-1px);
}

.nav-link i {
    margin-right: 8px;
}

.header h1 {
    color: #2c3e50;
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 10px;
}

.header h1 i {
    color: #3498db;
    margin-right: 15px;
}

.lesson-info {
    text-align: center;
    font-size: 1.2rem;
    color: #7f8c8d;
    font-weight: 500;
}

/* 메인 컨텐츠 */
.main {
    padding-bottom: 50px;
}

/* 섹션 공통 스타일 */
section {
    background: rgba(255, 255, 255, 0.95);
    margin-bottom: 30px;
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(10px);
}

section h2 {
    color: #2c3e50;
    font-size: 1.8rem;
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 3px solid #3498db;
}

section h2 i {
    color: #3498db;
    margin-right: 10px;
}

/* 수업 목표 섹션 */
.lesson-objectives ul {
    list-style: none;
    padding-left: 0;
}

.lesson-objectives li {
    padding: 12px 0;
    padding-left: 30px;
    position: relative;
    font-size: 1.1rem;
    color: #555;
}

.lesson-objectives li::before {
    content: "✈";
    position: absolute;
    left: 0;
    color: #3498db;
    font-size: 1.2rem;
}

/* 조종기 기본 동작 섹션 */
.controller-layout {
    margin-bottom: 30px;
}

.controller-diagram {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    margin-bottom: 30px;
}

.left-stick, .right-stick {
    background: linear-gradient(145deg, #f8f9fa, #e9ecef);
    padding: 25px;
    border-radius: 15px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.left-stick h3, .right-stick h3 {
    color: #2c3e50;
    text-align: center;
    margin-bottom: 20px;
    font-size: 1.3rem;
    font-weight: 600;
}

.stick-actions {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.stick-action {
    display: flex;
    align-items: center;
    padding: 12px 15px;
    background: white;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
}

.stick-action:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.stick-action i {
    color: #3498db;
    font-size: 1.2rem;
    margin-right: 15px;
    width: 20px;
}

.stick-action span {
    font-weight: 500;
    color: #2c3e50;
}

/* 데모 섹션 */
.demo-section {
    background: linear-gradient(135deg, #74b9ff, #0984e3);
    color: white;
    padding: 25px;
    border-radius: 15px;
    margin-top: 20px;
}

.demo-section h3 {
    margin-bottom: 20px;
    font-size: 1.4rem;
}

.demo-steps {
    list-style: none;
    counter-reset: step-counter;
}

.demo-steps li {
    counter-increment: step-counter;
    padding: 12px 0;
    padding-left: 50px;
    position: relative;
    font-size: 1.1rem;
}

.demo-steps li::before {
    content: counter(step-counter);
    position: absolute;
    left: 0;
    top: 8px;
    background: rgba(255, 255, 255, 0.2);
    color: white;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
}

/* 기본 비행 실습 섹션 */
.pattern-steps {
    display: grid;
    gap: 25px;
}

.step {
    background: linear-gradient(145deg, #f8f9fa, #e9ecef);
    padding: 25px;
    border-radius: 15px;
    position: relative;
    border-left: 5px solid #3498db;
}

.step-number {
    position: absolute;
    top: -10px;
    left: -10px;
    background: #3498db;
    color: white;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    font-size: 1.2rem;
    box-shadow: 0 4px 15px rgba(52, 152, 219, 0.3);
}

.step h4 {
    color: #2c3e50;
    margin-bottom: 15px;
    font-size: 1.3rem;
    margin-left: 20px;
}

.step p {
    color: #555;
    font-size: 1.1rem;
    margin-bottom: 15px;
    line-height: 1.7;
}

.safety-tip {
    display: flex;
    align-items: center;
    background: #fff3cd;
    border: 1px solid #ffeaa7;
    padding: 10px 15px;
    border-radius: 8px;
    margin-top: 10px;
}

.safety-tip i {
    color: #f39c12;
    margin-right: 10px;
}

.safety-tip span {
    color: #856404;
    font-weight: 500;
}

/* 안전 규칙 섹션 */
.safety-categories {
    display: grid;
    gap: 30px;
}

.safety-category {
    background: linear-gradient(145deg, #f8f9fa, #e9ecef);
    padding: 25px;
    border-radius: 15px;
}

.safety-category h3 {
    color: #2c3e50;
    margin-bottom: 20px;
    font-size: 1.4rem;
    display: flex;
    align-items: center;
}

.safety-category h3 i {
    margin-right: 10px;
    color: #e74c3c;
}

/* 체크리스트 스타일 */
.checklist {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.checklist-item {
    display: flex;
    align-items: center;
    cursor: pointer;
    padding: 15px;
    background: white;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
    position: relative;
}

.checklist-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.checklist-item input[type="checkbox"] {
    display: none;
}

.checkmark {
    width: 25px;
    height: 25px;
    border: 2px solid #3498db;
    border-radius: 6px;
    margin-right: 15px;
    position: relative;
    transition: all 0.3s ease;
}

.checklist-item input:checked + .checkmark {
    background: #3498db;
    border-color: #3498db;
}

.checklist-item input:checked + .checkmark::after {
    content: "✓";
    position: absolute;
    color: white;
    font-weight: bold;
    font-size: 16px;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.checklist-item input:checked ~ span {
    color: #27ae60;
    text-decoration: line-through;
}

/* 취급 팁 스타일 */
.handling-tips {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.tip {
    display: flex;
    align-items: flex-start;
    padding: 20px;
    background: white;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.tip i {
    font-size: 1.5rem;
    margin-right: 15px;
    margin-top: 5px;
}

.tip i.fa-check-circle {
    color: #27ae60;
}

.tip i.fa-times-circle {
    color: #e74c3c;
}

.tip h4 {
    color: #2c3e50;
    margin-bottom: 8px;
    font-size: 1.2rem;
}

.tip p {
    color: #555;
    line-height: 1.6;
}

/* 긴급상황 대처법 */
.emergency-procedures {
    display: grid;
    gap: 25px;
}

.emergency-case {
    background: white;
    padding: 20px;
    border-radius: 10px;
    border-left: 5px solid #e74c3c;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.emergency-case h4 {
    color: #e74c3c;
    margin-bottom: 15px;
    font-size: 1.2rem;
    display: flex;
    align-items: center;
}

.emergency-case h4 i {
    margin-right: 8px;
}

.emergency-case ol {
    padding-left: 20px;
}

.emergency-case li {
    padding: 8px 0;
    color: #555;
    line-height: 1.6;
}

/* 실습 체크리스트 섹션 */
.student-progress {
    background: linear-gradient(145deg, #f8f9fa, #e9ecef);
    padding: 25px;
    border-radius: 15px;
}

.student-info {
    margin-bottom: 25px;
}

.student-info label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: #2c3e50;
}

.student-info input {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

.student-info input:focus {
    outline: none;
    border-color: #3498db;
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
}

.skill-checklist h4 {
    color: #2c3e50;
    margin-bottom: 20px;
    font-size: 1.3rem;
}

.progress-result {
    margin-top: 30px;
    text-align: center;
}

.completion-rate {
    margin-bottom: 20px;
}

.completion-rate span:first-child {
    font-weight: 600;
    color: #2c3e50;
    font-size: 1.1rem;
}

#completion-percentage {
    font-weight: bold;
    color: #3498db;
    font-size: 1.3rem;
}

.progress-bar {
    width: 100%;
    height: 20px;
    background: #e9ecef;
    border-radius: 10px;
    overflow: hidden;
    margin: 15px 0;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.1);
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #74b9ff, #0984e3);
    width: 0%;
    transition: width 0.5s ease;
    border-radius: 10px;
}

.btn-primary {
    background: linear-gradient(135deg, #74b9ff, #0984e3);
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 25px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(116, 185, 255, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(116, 185, 255, 0.4);
}

.btn-primary:active {
    transform: translateY(0);
}

/* 장애물 미션 섹션 */
.mission-description p {
    font-size: 1.1rem;
    color: #555;
    margin-bottom: 25px;
    line-height: 1.7;
}

.mission-setup {
    background: linear-gradient(145deg, #f8f9fa, #e9ecef);
    padding: 20px;
    border-radius: 10px;
    margin-bottom: 25px;
}

.mission-setup h3 {
    color: #2c3e50;
    margin-bottom: 15px;
    font-size: 1.3rem;
}

.mission-setup ul {
    padding-left: 20px;
}

.mission-setup li {
    padding: 8px 0;
    color: #555;
    line-height: 1.6;
}

.mission-levels {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}

.mission-level {
    background: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    border-top: 4px solid #3498db;
    transition: all 0.3s ease;
}

.mission-level:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.mission-level h4 {
    color: #2c3e50;
    margin-bottom: 10px;
    font-size: 1.2rem;
}

.mission-level p {
    color: #555;
    line-height: 1.6;
}

/* 푸터 */
.footer {
    background: rgba(44, 62, 80, 0.95);
    color: white;
    text-align: center;
    padding: 25px 0;
    margin-top: 50px;
    backdrop-filter: blur(10px);
}

.footer p {
    font-size: 1rem;
    opacity: 0.9;
}

/* 반응형 디자인 */
@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }
    
    .header h1 {
        font-size: 2rem;
    }
    
    .lesson-info {
        font-size: 1rem;
    }
    
    .controller-diagram {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    section {
        padding: 20px;
        margin-bottom: 20px;
    }
    
    section h2 {
        font-size: 1.5rem;
    }
    
    .mission-levels {
        grid-template-columns: 1fr;
    }
    
    .step {
        padding: 20px;
    }
    
    .step h4 {
        font-size: 1.1rem;
    }
    
    .btn-primary {
        padding: 12px 25px;
        font-size: 1rem;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 1.7rem;
    }
    
    .lesson-info {
        font-size: 0.9rem;
    }
    
    section {
        padding: 15px;
    }
    
    .left-stick, .right-stick {
        padding: 15px;
    }
    
    .step {
        padding: 15px;
    }
    
    .step-number {
        width: 30px;
        height: 30px;
        font-size: 1rem;
    }
    
    .student-progress {
        padding: 15px;
    }
}

/* 애니메이션 효과 */
@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

section {
    animation: slideInUp 0.6s ease-out;
}

/* 인쇄용 스타일 */
@media print {
    body {
        background: white;
        color: black;
    }
    
    .header, .footer {
        background: white;
        color: black;
    }
    
    section {
        background: white;
        box-shadow: none;
        border: 1px solid #ddd;
        break-inside: avoid;
    }
    
    .btn-primary {
        display: none;
    }
}