:root {
    --bg-color: #0f172a;
    --card-bg: rgba(30, 41, 59, 0.7);
    --border-color: rgba(255, 255, 255, 0.1);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #06b6d4;
    --accent-hover: #0891b2;
    --btn-secondary: #334155;
    --success: #10b981;
    --font-family: 'Outfit', sans-serif;
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-family);
    height: 100vh;
    overflow: hidden;
    background-image: radial-gradient(circle at top right, #1e1b4b, #0f172a);
}

.app-container {
    display: flex;
    height: 100vh;
    padding: 1rem;
    gap: 1rem;
}

.glass-card {
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.2);
}

/* Left Panel */
.left-panel {
    width: 380px;
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    overflow-y: auto;
    gap: 1.5rem;
}

.left-panel::-webkit-scrollbar { width: 6px; }
.left-panel::-webkit-scrollbar-thumb { background: var(--btn-secondary); border-radius: 4px; }

header h1 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--accent-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.control-group h3 {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* Tabs and Input */
.dataset-tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.tab-btn {
    flex: 1;
    background: rgba(0,0,0,0.2);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.6rem;
    border-radius: 6px;
    cursor: pointer;
    font-family: inherit;
    transition: 0.2s;
}
.tab-btn.active {
    background: var(--accent-color);
    color: white;
    border-color: var(--accent-color);
}

textarea {
    width: 100%;
    background: rgba(0,0,0,0.2);
    border: 1px solid var(--border-color);
    color: white;
    padding: 0.8rem;
    border-radius: 6px;
    font-family: monospace;
    font-size: 0.85rem;
    resize: vertical;
    outline: none;
}
textarea:focus { border-color: var(--accent-color); }

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 1.5rem 1rem;
    text-align: center;
    transition: all 0.3s ease;
}
.upload-area:hover, .upload-area.dragover { border-color: var(--accent-color); background: rgba(6, 182, 212, 0.05); }
.upload-area i { font-size: 2rem; color: var(--accent-color); margin-bottom: 0.5rem; }
.upload-btn { color: var(--accent-color); cursor: pointer; text-decoration: underline; }

/* Tables */
.table-container {
    max-height: 150px;
    overflow-y: auto;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    margin-bottom: 1rem;
    background: rgba(0,0,0,0.2);
}
.table-container::-webkit-scrollbar { width: 4px;}
.table-container::-webkit-scrollbar-thumb { background: var(--border-color); }

table { width: 100%; border-collapse: collapse; font-size: 0.85rem; }
th, td { padding: 0.5rem; text-align: left; border-bottom: 1px solid var(--border-color); }
th { background: rgba(30,41,59,0.9); position: sticky; top: 0; }

/* Form Controls */
select, input[type="number"], input[type="range"] {
    width: 100%;
    padding: 0.8rem;
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid var(--border-color);
    color: white;
    border-radius: 6px;
    font-family: inherit;
    margin-bottom: 0.5rem;
    outline: none;
    transition: 0.2s;
}
select:focus, input:focus { border-color: var(--accent-color); }

.params-group {
    background: rgba(0,0,0,0.1);
    padding: 1rem;
    border-radius: 8px;
}
.params-group label {
    display: block;
    margin-bottom: 0.4rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.new-point-inputs { display: flex; gap: 0.5rem; }

/* Buttons */
.btn {
    width: 100%;
    padding: 0.8rem;
    border: none;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    font-family: inherit;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}
.primary-btn { background: var(--accent-color); color: white; font-size: 1.1rem; margin-top: auto; }
.primary-btn:hover { background: var(--accent-hover); transform: translateY(-2px); box-shadow: 0 4px 12px rgba(6, 182, 212, 0.4); }
.secondary-btn { background: var(--btn-secondary); color: white; }
.secondary-btn:hover { background: #475569; }

/* Right Panel */
.right-panel {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    overflow-y: auto; /* Fixes right-side overflow issues */
    min-width: 0;
}
.right-panel::-webkit-scrollbar { width: 6px; }
.right-panel::-webkit-scrollbar-thumb { background: var(--btn-secondary); }

.chart-container {
    flex: 1;
    padding: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    min-height: 400px;
}

#visualizerChart {
    width: 100% !important;
    height: 100% !important;
}

.player-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 2rem;
    min-height: 100px;
}

.step-explanation { flex: 1; }
.step-explanation h3 { font-size: 0.9rem; color: var(--text-secondary); margin-bottom: 0.2rem; text-transform: uppercase; }
.step-explanation p { font-size: 1.2rem; font-weight: 600; }

.controls-wrapper { display: flex; align-items: center; gap: 1rem; }

.icon-btn {
    background: var(--btn-secondary);
    border: none;
    color: white;
    width: 45px;
    height: 45px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.1rem;
    transition: transform 0.2s, background 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}
.icon-btn:hover { background: var(--accent-hover); transform: scale(1.1); }
.icon-btn:active { transform: scale(0.95); }

.speed-control {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.3rem;
    margin-left: 1rem;
    font-size: 0.8rem;
    color: var(--text-secondary);
}
.speed-control input { width: 100px; }

.output-group {
    background: rgba(16, 185, 129, 0.1);
    border-color: rgba(16, 185, 129, 0.3);
    padding: 1rem;
}
.output-group h3 { color: var(--success); }

/* Responsive */
@media (max-width: 900px) {
    .app-container {
        flex-direction: column;
        overflow-y: auto;
    }
    .left-panel {
        width: 100%;
        max-height: none;
    }
    .right-panel {
        overflow-y: visible;
        min-height: 600px;
    }
}

/* Tree DOM Styling */
.tree {
    display: inline-block;
    padding-top: 10px;
}
.tree ul {
    padding-top: 20px; position: relative;
    transition: all 0.5s;
    display: flex;
    justify-content: center;
}
.tree li {
    float: left; text-align: center;
    list-style-type: none;
    position: relative;
    padding: 20px 10px 0 10px;
    transition: all 0.5s;
}
.tree li::before, .tree li::after{
    content: '';
    position: absolute; top: 0; right: 50%;
    border-top: 2px solid var(--border-color);
    width: 50%; height: 20px;
}
.tree li::after{
    right: auto; left: 50%;
    border-left: 2px solid var(--border-color);
}
.tree li:only-child::after, .tree li:only-child::before {
    display: none;
}
.tree li:only-child{ padding-top: 0;}
.tree li:first-child::before, .tree li:last-child::after{
    border: 0 none;
}
.tree li:first-child::after{
    border-radius: 5px 0 0 0;
}
.tree li:last-child::before{
    border-right: 2px solid var(--border-color);
    border-radius: 0 5px 0 0;
}
.tree ul ul::before{
    content: '';
    position: absolute; top: 0; left: 50%;
    border-left: 2px solid var(--border-color);
    width: 0; height: 20px;
}
.tree-node-content {
    background: var(--card-bg);
    border: 1px solid var(--accent-color);
    padding: 10px;
    border-radius: 8px;
    display: inline-block;
    min-width: 100px;
    color: white;
}
.tree-leaf {
    border-color: var(--success);
    background: rgba(16, 185, 129, 0.2);
}