:root {
    --primary-color: #003B46;
    --secondary-color: #07575B;
    --accent-color: #66A5AD;
    --bg-color: #F0F7F9;
    --sidebar-bg: #FFFFFF;
    --text-primary: #1B1B1B;
    --text-secondary: #424242;
    --border-color: #E0E0E0;
    --card-bg: #FFFFFF;
    --nav-height: 70px;
    --sidebar-width: 280px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    color: var(--text-primary);
    background-color: var(--bg-color);
    line-height: 1.6;
    overflow-x: hidden;
}

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 6px;
}
::-webkit-scrollbar-track {
    background: transparent;
}
::-webkit-scrollbar-thumb {
    background: var(--accent-color);
    border-radius: 10px;
}

/* Layout */
.container {
    display: flex;
    min-height: 100vh;
}

/* Header */
header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background: var(--primary-color);
    color: white;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 32px;
    z-index: 1000;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
}

.logo-container {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.5px;
    display: flex;
    align-items: center;
    line-height: 1;
    gap: 8px;
}

.logo-text small {
    font-size: 0.6em;
    opacity: 0.7;
    font-weight: 500;
    margin-top: 2px;
}

.nav-links {
    display: flex;
    gap: 24px;
}

.nav-links a {
    color: rgba(255,255,255,0.8);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    transition: var(--transition);
}

.nav-links a:hover {
    color: white;
}

/* Sidebar */
aside {
    width: var(--sidebar-width);
    background: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    padding: 100px 24px 40px;
    position: fixed;
    height: 100vh;
    overflow-y: auto;
    transition: var(--transition);
}

.sidebar-nav ul {
    list-style: none;
}

.sidebar-nav .nav-category {
    font-size: 0.75rem;
    text-transform: uppercase;
    color: var(--text-secondary);
    letter-spacing: 1px;
    font-weight: 700;
    margin-bottom: 12px;
    margin-top: 24px;
}

.sidebar-nav li a {
    display: block;
    padding: 10px 16px;
    color: var(--text-secondary);
    text-decoration: none;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 500;
    transition: var(--transition);
    margin-bottom: 4px;
}

.sidebar-nav li a:hover, .sidebar-nav li a.active {
    background: rgba(102, 165, 173, 0.1);
    color: var(--primary-color);
}

.sidebar-nav li a.active {
    background: var(--accent-color);
    color: white;
}

.sidebar-nav li a i {
    display: inline-block;
    vertical-align: middle;
    margin-right: 8px;
    margin-top: -2px;
}

.mobile-only {
    display: none;
}

/* Main Content */
main {
    flex: 1;
    margin-left: var(--sidebar-width);
    padding: 120px 60px 80px;
    max-width: 1000px;
}

.content-section {
    margin-bottom: 80px;
    scroll-margin-top: 120px;
}

h1 {
    font-size: 3rem;
    margin-bottom: 16px;
    color: var(--primary-color);
    letter-spacing: -1px;
}

h2 {
    font-size: 1.8rem;
    margin-bottom: 24px;
    margin-top: 48px;
    color: var(--secondary-color);
    display: flex;
    align-items: center;
    gap: 12px;
}

h2::before {
    content: "";
    width: 6px;
    height: 24px;
    background: var(--accent-color);
    display: inline-block;
    border-radius: 10px;
}

p {
    margin-bottom: 20px;
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Image Placeholder Styling */
.image-placeholder {
    background: #E8F1F3;
    border: 2px dashed var(--accent-color);
    border-radius: 16px;
    height: 400px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    margin: 32px 0;
    color: var(--secondary-color);
    position: relative;
    overflow: hidden;
}

.image-placeholder i {
    font-size: 3rem;
    margin-bottom: 12px;
}

.image-placeholder span {
    font-weight: 600;
}

.image-placeholder .recommend-size {
    display: block;
    font-size: 0.8rem;
    opacity: 0.6;
    margin-top: 8px;
    background: var(--primary-color);
    color: white;
    padding: 4px 12px;
    border-radius: 20px;
    font-family: monospace;
}

/* Callout Box */
.callout {
    background: white;
    padding: 24px;
    border-radius: 12px;
    border-left: 5px solid var(--accent-color);
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    margin: 32px 0;
}

.callout h4 {
    margin-bottom: 8px;
    color: var(--primary-color);
}

/* Footer */
footer {
    border-top: 1px solid var(--border-color);
    padding: 40px 0;
    margin-top: 80px;
    text-align: center;
    color: var(--text-secondary);
}

/* Mobile Toggle */
.menu-toggle {
    display: none;
    cursor: pointer;
    background: rgba(255,255,255,0.1);
    padding: 8px;
    border-radius: 8px;
    border: 1px solid rgba(255,255,255,0.2);
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.menu-toggle:hover {
    background: rgba(255,255,255,0.2);
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.content-section {
    animation: fadeIn 0.8s ease-out;
}

/* Responsive */
@media (max-width: 992px) {
    aside {
        transform: translateX(-100%);
    }
    
    aside.open {
        transform: translateX(0);
        z-index: 1001;
    }
    
    main {
        margin-left: 0;
        padding: 100px 32px 40px;
    }
    
    .nav-links {
        display: none;
    }

    .mobile-only {
        display: block;
    }
    
    .menu-toggle {
        display: flex;
        color: white;
        z-index: 1002;
    }

    .menu-toggle svg {
        width: 24px;
        height: 24px;
        display: block;
    }
}