:root {
    --bg-color: #0f1115;
    --sidebar-bg: #161b22;
    --card-bg: #1c2128;
    --text-primary: #e6edf3;
    --text-secondary: #8b949e;
    --accent-color: #58a6ff;
    --success-color: #238636;
    --border-color: #30363d;
    --font-main: 'Inter', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
}

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

body {
    font-family: var(--font-main);
    background-color: var(--bg-color);
    color: var(--text-primary);
    display: flex;
    height: 100vh;
    overflow: hidden;
}

/* Sidebar */
.sidebar {
    width: 280px;
    background-color: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    flex-shrink: 0;
}

.logo-area {
    margin-bottom: 2rem;
}

.logo-area h1 {
    font-weight: 800;
    font-size: 1.5rem;
    letter-spacing: -0.5px;
    background: linear-gradient(45deg, var(--accent-color), #bc8cff);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.logo-area p {
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 400;
}

#main-nav {
    flex-grow: 1;
    overflow-y: auto;
}

.nav-item {
    display: block;
    padding: 0.75rem 1rem;
    margin-bottom: 0.5rem;
    border-radius: 6px;
    color: var(--text-secondary);
    text-decoration: none;
    transition: all 0.2s;
    cursor: pointer;
    font-size: 0.95rem;
}

.nav-item:hover {
    background-color: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
}

.nav-item.active {
    background-color: rgba(88, 166, 255, 0.1);
    color: var(--accent-color);
    border-left: 3px solid var(--accent-color);
}

.nav-item.locked {
    opacity: 0.5;
    cursor: not-allowed;
    position: relative;
}

.nav-item.locked::after {
    content: '🔒';
    position: absolute;
    right: 10px;
    font-size: 0.8rem;
}

/* Progress Area */
.progress-container {
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.progress-container p {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.progress-bar {
    height: 6px;
    background-color: var(--border-color);
    border-radius: 3px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background-color: var(--success-color);
    transition: width 0.3s ease;
}

/* Main Content */
.content-area {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    padding: 2rem 3rem;
    overflow-y: auto;
}

header {
    margin-bottom: 2rem;
}

#page-title {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.breadcrumb {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Glass Panel for Content */
.glass-panel {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2.5rem;
    min-height: 400px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
}

.welcome-screen h3 {
    margin-bottom: 1rem;
    color: var(--accent-color);
}

.welcome-screen p {
    line-height: 1.6;
    margin-bottom: 2rem;
    max-width: 600px;
}

.module-card {
    background-color: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    cursor: pointer;
    transition: transform 0.2s, border-color 0.2s;
    max-width: 400px;
}

.module-card:hover {
    transform: translateY(-2px);
    border-color: var(--accent-color);
}

.module-card .tag {
    display: inline-block;
    background-color: var(--accent-color);
    color: #000;
    font-size: 0.7rem;
    padding: 2px 8px;
    border-radius: 4px;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.module-card h4 {
    margin-bottom: 0.5rem;
}

.module-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 0;
}