/* 구구단 앱 - read_clock과 동일한 디자인 */

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

/* 헤더 네비게이션 스타일 (루트 페이지와 완전히 동일) */
.header {
    background: #ffffff;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 20px rgba(0,0,0,0.08);
    border-bottom: 1px solid #E9ECEF;
}

.header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    color: #FF6B35;
}

.logo-icon {
    font-size: 28px;
    filter: drop-shadow(0 2px 4px rgba(255,107,53,0.2));
}

.logo-text {
    font-size: 24px;
    font-weight: 700;
    letter-spacing: -0.02em;
    color: #FF6B35;
}

.nav-menu ul {
    display: flex;
    list-style: none;
    gap: 32px;
    align-items: center;
}

.nav-menu a {
    text-decoration: none;
    color: #2C3E50;
    font-weight: 500;
    font-size: 15px;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    padding: 8px 16px;
    border-radius: 8px;
}

.nav-menu a:hover {
    background: rgba(255,107,53,0.1);
    color: #FF6B35;
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(255,107,53,0.15);
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: #2C3E50;
    transition: 0.3s;
    border-radius: 2px;
}

/* 반응형 헤더 */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        display: none;
    }
    
    .nav-menu.active {
        display: block;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: white;
        box-shadow: 0 4px 20px rgba(0,0,0,0.1);
        padding: 20px;
    }
    
    .nav-menu.active ul {
        flex-direction: column;
        gap: 20px;
    }
}

body {
    font-family: 'Segoe UI', 'Roboto', 'Helvetica Neue', 'Arial', 'Noto Sans', sans-serif;
    background: #ffffff;
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
    padding-bottom: 120px; /* 푸터 공간 */
}

/* 메인 컨텐츠 */
.main-content {
    margin-top: 0;
    min-height: calc(100vh - 120px);
}

/* 구구단 메인 컨테이너 */
.main-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 20px;
    text-align: center;
}

.main-title {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
    margin-bottom: 20px;
    font-size: 2.5rem;
    font-weight: 700;
    color: #FF6B35;
}

.main-title-icon {
    font-size: 3rem;
    filter: drop-shadow(0 4px 8px rgba(255,107,53,0.3));
}

.main-desc {
    font-size: 1.2rem;
    color: #666;
    margin-bottom: 40px;
    line-height: 1.6;
}

.main-menu {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

.main-menu-btn {
    background: #ffffff;
    border: 2px solid #e9ecef;
    border-radius: 20px;
    padding: 30px;
    cursor: pointer;
    transition: all 0.3s ease;
    min-width: 250px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
}

.main-menu-btn:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 50px rgba(0,0,0,0.15);
    border-color: #FF6B35;
}

.main-menu-btn .icon {
    font-size: 3rem;
    filter: drop-shadow(0 4px 8px rgba(0,0,0,0.1));
}

.main-menu-btn .text {
    text-align: center;
}

.main-menu-btn .text div:first-child {
    font-size: 1.5rem;
    font-weight: 700;
    color: #333;
    margin-bottom: 8px;
}

.main-menu-btn .text .description {
    font-size: 1rem;
    color: #666;
    line-height: 1.4;
}

.learn-btn:hover {
    border-color: #4CAF50;
    box-shadow: 0 20px 50px rgba(76, 175, 80, 0.2);
}

.master-btn:hover {
    border-color: #FF9800;
    box-shadow: 0 20px 50px rgba(255, 152, 0, 0.2);
}

.footer-hint {
    font-size: 1rem;
    color: #999;
    margin-top: 40px;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 10px;
    border: 1px solid #e9ecef;
}

/* 반응형 디자인 */
@media (max-width: 768px) {
    .main-container {
        padding: 30px 15px;
    }
    
    .main-title {
        font-size: 2rem;
        flex-direction: column;
        gap: 10px;
    }
    
    .main-title-icon {
        font-size: 2.5rem;
    }
    
    .main-desc {
        font-size: 1.1rem;
        margin-bottom: 30px;
    }
    
    .main-menu {
        gap: 20px;
    }
    
    .main-menu-btn {
        min-width: 200px;
        padding: 25px 20px;
    }
    
    .main-menu-btn .icon {
        font-size: 2.5rem;
    }
    
    .main-menu-btn .text div:first-child {
        font-size: 1.3rem;
    }
    
    .main-menu-btn .text .description {
        font-size: 0.9rem;
    }
}

@media (max-width: 480px) {
    .main-container {
        padding: 20px 10px;
    }
    
    .main-title {
        font-size: 1.8rem;
    }
    
    .main-title-icon {
        font-size: 2rem;
    }
    
    .main-desc {
        font-size: 1rem;
        margin-bottom: 25px;
    }
    
    .main-menu {
        gap: 15px;
    }
    
    .main-menu-btn {
        min-width: 180px;
        padding: 20px 15px;
    }
    
    .main-menu-btn .icon {
        font-size: 2rem;
    }
    
    .main-menu-btn .text div:first-child {
        font-size: 1.2rem;
    }
    
    .main-menu-btn .text .description {
        font-size: 0.85rem;
    }
    
    .footer-hint {
        font-size: 0.9rem;
        padding: 15px;
        margin-top: 30px;
    }
}