/* Problem Page Styles */

/* Breadcrumb */
.breadcrumb {
    padding: 1rem 0;
    background: var(--surface);
    border-bottom: 2px solid var(--border-color);
    position: fixed;
    top: 0;
    left: 280px;
    right: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
}

.breadcrumb .container {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9375rem;
}

.breadcrumb a {
    color: var(--primary);
    text-decoration: none;
    transition: var(--transition);
    font-weight: 500;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
}

.breadcrumb a:hover {
    background: var(--bg-secondary);
    color: var(--primary-hover);
}

.breadcrumb .separator {
    margin: 0 0.25rem;
    color: var(--text-tertiary);
    font-weight: 600;
}

.breadcrumb span:last-child {
    color: var(--text-primary);
    font-weight: 600;
    padding: 0.25rem 0.5rem;
    background: var(--bg-secondary);
    border-radius: 4px;
}

.problem-layout {
    display: flex;
    min-height: 100vh;
    background: var(--bg-primary);
}

/* Sidebar */
.sidebar {
    width: 280px;
    background: var(--surface);
    border-right: 2px solid var(--border-color);
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    overflow-y: auto;
    flex-shrink: 0;
    z-index: 90;
}

.sidebar-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.sidebar-title {
    font-family: 'Poppins', sans-serif;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 0.5rem;
}

.sidebar-problem-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.4;
}

.sidebar-nav {
    padding: 1rem 0;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1.5rem;
    color: var(--text-secondary);
    text-decoration: none;
    transition: var(--transition);
    cursor: pointer;
    border-left: 3px solid transparent;
}

.nav-item:hover {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

.nav-item.active {
    background: var(--bg-secondary);
    color: var(--primary);
    border-left-color: var(--primary);
    font-weight: 500;
}

.nav-item-icon {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
}

.nav-item-icon.check {
    color: var(--success);
}

.nav-item-icon.current {
    color: var(--primary);
}

.nav-item-text {
    flex: 1;
    font-size: 0.875rem;
    line-height: 1.4;
}

/* Main Content */
.main-content {
    flex: 1;
    min-width: 0;
    margin-left: 280px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background: var(--bg-secondary);
}

.content-header {
    margin-top: 60px;
    padding: 2rem 2rem 1.5rem;
    background: var(--surface);
    border-bottom: 1px solid var(--border-color);
    border-left: none;
}

/* Page-like content wrapper — centered with boundaries on both sides */
.content-body {
    flex: 1;
    padding: 2rem 1rem;
    display: flex;
    justify-content: center;
    background: var(--bg-secondary);
}

.markdown-content {
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2.5rem 3rem;
    max-width: 1000px;
    width: 100%;
    box-shadow: var(--shadow-sm);
}

.content-title {
    font-family: 'Poppins', sans-serif;
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.content-meta {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    font-size: 0.875rem;
    color: var(--text-tertiary);
}

.content-meta-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.content-navigation {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    padding: 1.5rem 2rem;
    border-top: 1px solid var(--border-color);
    background: var(--surface);
}

.nav-button {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    cursor: pointer;
}

.nav-button:hover:not(:disabled) {
    background: var(--surface);
    border-color: var(--primary);
    transform: translateY(-2px);
}

.nav-button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.nav-button.prev svg {
    order: -1;
}

.nav-button.next svg {
    order: 1;
}

/* Loading State */
.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 400px;
    color: var(--text-secondary);
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Error State */
.error {
    padding: 3rem 2rem;
    text-align: center;
    color: var(--text-secondary);
}

.error-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.error-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.error-message {
    margin-bottom: 1.5rem;
}

/* Mobile Sidebar Toggle */
.sidebar-toggle {
    display: none;
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 56px;
    height: 56px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 50%;
    box-shadow: var(--shadow-lg);
    cursor: pointer;
    z-index: 999;
    transition: var(--transition);
}

.sidebar-toggle:hover {
    transform: scale(1.1);
}

.sidebar-toggle svg {
    width: 24px;
    height: 24px;
}

/* Responsive */
@media (max-width: 1024px) {
    .sidebar {
        width: 250px;
    }
    
    .content-body {
        padding: 2rem 1.5rem;
    }
}

@media (max-width: 768px) {
    .breadcrumb {
        left: 0;
    }
    
    .problem-layout {
        flex-direction: column;
    }
    
    .sidebar {
        position: fixed;
        top: 0;
        left: 0;
        width: 280px;
        height: 100vh;
        transform: translateX(-100%);
        transition: transform 0.3s ease;
        z-index: 998;
        box-shadow: var(--shadow-xl);
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .sidebar-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
    }
    
    .main-content {
        width: 100%;
        margin-left: 0;
    }
    
    .content-header {
        padding: 1.5rem 1rem;
    }
    
    .content-title {
        font-size: 1.5rem;
    }
    
    .content-meta {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }

    .content-body {
        padding: 1rem;
    }

    .markdown-content {
        padding: 1.5rem 1.25rem;
        border-radius: 8px;
    }
    
    .content-body {
        padding: 2rem 1rem;
    }
    
    .content-navigation {
        flex-direction: column;
        padding: 1.5rem 1rem;
    }
    
    .nav-button {
        width: 100%;
        justify-content: center;
    }
}

/* Sidebar Scrollbar */
.sidebar::-webkit-scrollbar {
    width: 6px;
}

.sidebar::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

.sidebar::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 3px;
}

.sidebar::-webkit-scrollbar-thumb:hover {
    background: var(--text-tertiary);
}

/* Print Styles */
@media print {
    .sidebar,
    .sidebar-toggle,
    .theme-toggle,
    .breadcrumb,
    .content-navigation {
        display: none;
    }
    
    .main-content {
        width: 100%;
    }
    
    .content-body {
        max-width: 100%;
    }
}