.seo-h1 {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip: rect(0,0,0,0);
    white-space: nowrap;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Arial, sans-serif;
    background: #282c34;
    color: #abb2bf;
    height: 100vh;
    overflow: hidden;
}

.app-container {
    display: flex;
    height: 100vh;
}

.left-panel {
    width: 35%;
    min-width: 280px;
    max-width: 420px;
    flex-shrink: 0;
    background: #21252b;
    display: flex;
    flex-direction: column;
    border-right: 2px solid #181a1f;
}

.level-header {
    padding: 20px;
    background: #2c313a;
    border-bottom: 2px solid #181a1f;
    position: relative;
}

.user-badge {
    position: absolute;
    top: 20px;
    right: 20px;
    background: #61afef;
    color: #fff;
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 0.9em;
    display: flex;
    align-items: center;
    gap: 6px;
    box-shadow: 0 2px 8px rgba(97, 175, 239, 0.3);
}

.user-badge.hidden {
    display: none;
}

.badge-icon {
    font-size: 1.1em;
}

.level-header h2 {
    color: #61afef;
    font-size: 1.3em;
    margin-bottom: 15px;
}

.level-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 10px;
}

.nav-btn {
    background: #61afef;
    color: #fff;
    border: none;
    padding: 8px 16px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9em;
    transition: background 0.2s;
}

.nav-btn:hover {
    background: #528bcc;
}

.nav-btn:disabled {
    background: #3e4451;
    cursor: not-allowed;
    opacity: 0.5;
}

#level-indicator {
    color: #abb2bf;
    font-size: 0.9em;
}

.instructions {
    flex: 1;
    padding: 20px 25px;
    overflow-y: auto;
    line-height: 1.6;
    font-size: 0.95em;
}

.instructions p {
    margin-bottom: 12px;
}

.instructions code {
    background: #282c34;
    padding: 2px 6px;
    border-radius: 3px;
    color: #98c379;
    font-family: 'Courier New', monospace;
}

.hint-box {
    margin: 15px 20px;
    padding: 12px;
    background: #2c313a;
    border-left: 4px solid #e5c07b;
    border-radius: 4px;
    color: #e5c07b;
    font-size: 0.85em;
}

.cheatsheet-link {
    color: #61afef;
    text-decoration: none;
    font-weight: 600;
    border-bottom: 1px dashed #61afef;
}

.cheatsheet-link:hover {
    color: #98c379;
    border-color: #98c379;
}

.privacy-note {
    margin: 15px 20px;
    padding: 12px;
    background: #2c313a;
    border-left: 4px solid #98c379;
    border-radius: 4px;
    color: #98c379;
    font-size: 0.8em;
    line-height: 1.5;
}

.code-editor {
    margin: 15px 20px;
    background: #1e2127;
    border-radius: 6px;
    overflow: hidden;
    border: 1px solid #3e4451;
    max-height: 200px;
}

.code-editor.hidden {
    display: none;
}

.code-header {
    background: #2c313a;
    padding: 8px 12px;
    display: flex;
    align-items: center;
    gap: 8px;
    border-bottom: 1px solid #3e4451;
}

.file-icon {
    font-size: 1em;
}

.file-name {
    color: #abb2bf;
    font-family: 'Courier New', monospace;
    font-size: 0.85em;
}

.unsaved-indicator {
    color: #e5c07b;
    font-size: 0.8em;
    margin-left: auto;
}

.code-content {
    padding: 12px;
    margin: 0;
    color: #abb2bf;
    font-family: 'Courier New', monospace;
    font-size: 0.85em;
    line-height: 1.5;
    overflow-x: auto;
}

.code-content::selection {
    background: #3e4451;
}

.right-panel {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.visualization-container {
    flex: 1;
    background: #282c34;
    display: flex;
    flex-direction: column;
}

.viz-header {
    padding: 15px 20px;
    background: #2c313a;
    border-bottom: 2px solid #181a1f;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: #abb2bf;
    font-weight: 500;
    flex-shrink: 0;
}

.viz-controls {
    display: flex;
    align-items: center;
    gap: 10px;
}

.viz-title-section {
    display: flex;
    align-items: center;
    gap: 15px;
}

.viz-user-badge {
    background: #61afef;
    color: #fff;
    padding: 4px 10px;
    border-radius: 15px;
    font-size: 0.85em;
    display: flex;
    align-items: center;
    gap: 5px;
}

.viz-user-badge.hidden {
    display: none;
}

.reset-btn {
    background: #e06c75;
    color: #fff;
    border: none;
    padding: 8px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9em;
    transition: background 0.2s;
    white-space: nowrap;
}

.reset-btn:hover {
    background: #be5046;
}

.git-viz {
    flex: 1;
    overflow: auto;
    display: flex;
    align-items: flex-start;
    min-width: 0;
}

.commit-node {
    cursor: pointer;
}

.commit-node circle {
    transition: r 0.15s ease;
}

.commit-node:hover circle {
    r: 22;
}

.commit-tooltip {
    pointer-events: none;
}

#tree-svg {
    display: block;
    flex-shrink: 0;
}

.viz-empty {
    margin: auto;
    color: #5c6370;
    font-size: 0.9em;
    font-family: 'Courier New', monospace;
}

.terminal-container {
    height: 80px;
    background: #1e2127;
    border-top: 2px solid #181a1f;
    border-bottom: 2px solid #181a1f;
    display: flex;
    flex-direction: column;
}

.terminal-header {
    padding: 10px 20px;
    background: #2c313a;
    color: #abb2bf;
    font-weight: 500;
    font-size: 0.9em;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.terminal-controls {
    display: flex;
    align-items: center;
    gap: 10px;
}

.user-badge {
    background: #61afef;
    color: #fff;
    padding: 4px 10px;
    border-radius: 15px;
    font-size: 0.85em;
    display: flex;
    align-items: center;
    gap: 5px;
}

.user-badge.hidden {
    display: none;
}

.output-container {
    height: 180px;
    background: #1e2127;
    display: flex;
    flex-direction: column;
}

.output-header {
    padding: 10px 20px;
    background: #2c313a;
    color: #abb2bf;
    font-weight: 500;
    font-size: 0.9em;
}

.terminal-output {
    flex: 1;
    padding: 15px;
    overflow-y: auto;
    font-family: 'Courier New', monospace;
    font-size: 0.9em;
}

.output-line {
    margin: 4px 0;
    color: #abb2bf;
}

.success {
    color: #98c379;
}

.error {
    color: #e06c75;
}

.info {
    color: #61afef;
}

.warning {
    color: #e5c07b;
}

.terminal-input-line {
    display: flex;
    align-items: center;
    padding: 15px;
    background: #282c34;
    flex: 1;
}

.prompt {
    color: #98c379;
    margin-right: 10px;
    font-family: 'Courier New', monospace;
    font-weight: bold;
    font-size: 1.1em;
}

#command-input {
    flex: 1;
    background: transparent;
    border: none;
    color: #abb2bf;
    font-family: 'Courier New', monospace;
    font-size: 1em;
    outline: none;
}

#command-input::placeholder {
    color: #5c6370;
}


@media (max-width: 1024px) {
    body {
        height: auto;
        overflow: auto;
    }

    .app-container {
        flex-direction: column;
        height: auto;
        min-height: 100vh;
    }
    
    .left-panel {
        width: 100%;
        max-width: none;
        height: auto;
        border-right: none;
        border-bottom: 2px solid #181a1f;
    }
    
    .instructions {
        max-height: 200px;
    }

    .visualization-container {
        min-height: 220px;
    }

    .terminal-container {
        height: 80px;
    }
    
    .output-container {
        height: 150px;
    }
}

@media (max-width: 768px) {
    .level-header {
        padding: 14px;
    }

    .level-header h2 {
        font-size: 1.1em;
    }

    .level-nav {
        flex-wrap: wrap;
        gap: 8px;
    }

    .nav-btn, .reset-btn {
        padding: 10px 18px;
        min-height: 44px;
        font-size: 1em;
    }

    .instructions {
        padding: 14px 16px;
        font-size: 0.9em;
        max-height: 180px;
    }

    .hint-box, .privacy-note {
        margin: 10px 14px;
        padding: 10px;
    }

    .code-editor {
        margin: 10px 14px;
    }

    #command-input {
        font-size: 16px; /* prevents iOS auto-zoom */
    }

    .terminal-input-line {
        padding: 12px;
    }

    .viz-header {
        padding: 10px 14px;
        font-size: 0.85em;
    }

    .terminal-output {
        font-size: 0.85em;
        padding: 10px;
    }
}

@media (max-width: 480px) {
    .level-header h2 {
        font-size: 1em;
        margin-bottom: 10px;
    }

    .nav-btn, .reset-btn {
        padding: 10px 12px;
        font-size: 0.9em;
    }

    #level-indicator {
        font-size: 0.8em;
    }

    .instructions {
        font-size: 0.85em;
        max-height: 160px;
    }

    .viz-title-section {
        flex-direction: column;
        align-items: flex-start;
        gap: 6px;
    }
}