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

body {
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    background: #2c3e50;
    min-height: 100vh;
    padding: 20px;
}

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

header {
    text-align: center;
    color: white;
    margin-bottom: 30px;
}

header h1 {
    font-size: 2.5em;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

header p {
    font-size: 1.2em;
    opacity: 0.9;
}

.system-selector {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 30px;
}

.system-btn {
    padding: 12px 24px;
    border: none;
    border-radius: 25px;
    background: rgba(255,255,255,0.2);
    color: white;
    font-size: 1.1em;
    cursor: pointer;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

.system-btn:hover {
    background: rgba(255,255,255,0.3);
    transform: translateY(-2px);
}

.system-btn.active {
    background: rgba(255,255,255,0.4);
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
}

.lesson-selector {
    background: rgba(255,255,255,0.1);
    padding: 20px;
    border-radius: 15px;
    margin-bottom: 30px;
    backdrop-filter: blur(10px);
}

.lesson-selector h3 {
    color: white;
    margin-bottom: 15px;
    text-align: center;
}

.lesson-buttons {
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
}

.lesson-btn {
    padding: 8px 16px;
    border: 2px solid rgba(255,255,255,0.3);
    border-radius: 20px;
    background: transparent;
    color: white;
    cursor: pointer;
    transition: all 0.3s ease;
}

.lesson-btn:hover {
    background: rgba(255,255,255,0.2);
}

.lesson-btn.active {
    background: rgba(255,255,255,0.3);
    border-color: rgba(255,255,255,0.6);
}

.main-content {
    display: flex;
    gap: 30px;
    align-items: flex-start;
}

.left-panel {
    flex: 0 0 400px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.right-panel {
    flex: 1;
}

.terminal-container {
    background: #0d1117;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 15px 35px rgba(0,0,0,0.4);
    margin-bottom: 30px;
    border: 1px solid #30363d;
}

.terminal-header {
    background: #21262d;
    padding: 12px 20px;
    display: flex;
    align-items: center;
    gap: 15px;
    border-bottom: 1px solid #30363d;
}

.terminal-controls {
    display: flex;
    gap: 8px;
}

.control {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.control.close {
    background: #ff5f57;
}

.control.minimize {
    background: #ffbd2e;
}

.control.maximize {
    background: #28ca42;
}

.terminal-title {
    color: #cccccc;
    font-size: 14px;
}

.terminal-body {
    background: #0d1117;
    color: #c9d1d9;
    padding: 24px;
    min-height: 400px;
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 14px;
    line-height: 1.5;
}

#terminal-output {
    margin-bottom: 15px;
    white-space: pre-wrap;
}

.input-line {
    display: flex;
    align-items: center;
}

#prompt {
    color: #58a6ff;
    margin-right: 8px;
    user-select: none;
    font-weight: 500;
}

#command-input {
    background: transparent;
    border: none;
    color: #c9d1d9;
    font-family: inherit;
    font-size: inherit;
    outline: none;
    flex: 1;
    caret-color: #58a6ff;
}

.help-panel {
    background: rgba(255,255,255,0.1);
    border-radius: 15px;
    padding: 20px;
    backdrop-filter: blur(10px);
    height: fit-content;
}

.help-header {
    margin-bottom: 15px;
}

.help-header h3 {
    color: white;
    text-align: center;
}

.help-content {
    color: white;
    line-height: 1.6;
    max-height: 400px;
    overflow-y: auto;
}

.command-example {
    background: rgba(0,0,0,0.3);
    padding: 10px;
    border-radius: 5px;
    margin: 10px 0;
    font-family: monospace;
}

.command-example code {
    color: #58a6ff;
}

.progress-panel {
    background: rgba(255,255,255,0.1);
    border-radius: 15px;
    padding: 20px;
    backdrop-filter: blur(10px);
    height: fit-content;
}

.progress-panel h3 {
    color: white;
    margin-bottom: 15px;
    text-align: center;
}

.progress-bar {
    background: rgba(255,255,255,0.2);
    height: 20px;
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 10px;
}

.progress-fill {
    background: #3fb950;
    height: 100%;
    width: 0%;
    transition: width 0.5s ease;
}

#progress-text {
    color: white;
    text-align: center;
    font-size: 14px;
}

.output-line {
    margin-bottom: 6px;
}

.output-command {
    color: #58a6ff;
    font-weight: 500;
}

.output-result {
    color: #e6edf3;
}

.output-error {
    color: #f85149;
    font-weight: 500;
}

.output-success {
    color: #3fb950;
    font-weight: 500;
}

.hint {
    background: rgba(88, 166, 255, 0.15);
    border-left: 4px solid #58a6ff;
    padding: 12px;
    margin: 12px 0;
    border-radius: 0 8px 8px 0;
    backdrop-filter: blur(5px);
}

.hint-text {
    color: #c9d1d9;
}

@media (max-width: 1024px) {
    .left-panel {
        flex: 0 0 350px;
    }
}

@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    .lesson-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .system-selector {
        flex-direction: column;
        align-items: center;
    }
    
    .main-content {
        flex-direction: column;
        gap: 20px;
    }
    
    .left-panel {
        flex: none;
        width: 100%;
    }
    
    .right-panel {
        flex: none;
        width: 100%;
    }
    
    .terminal-body {
        font-size: 12px;
        padding: 15px;
    }
    
    .help-content {
        max-height: 300px;
    }
}