:root {
    --bg-dark: #0f172a;
    --card-bg: #1e293b;
    --card-border: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-blue: #38bdf8;
    --accent-purple: #a855f7;
    --accent-green: #22c55e;
    --accent-yellow: #eab308;
    --accent-red: #ef4444;
    --accent-pink: #ec4899;
    --radius-lg: 16px;
    --radius-md: 10px;
    --shadow-glow: 0 10px 25px -5px rgba(56, 189, 248, 0.15);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

body {
    background-color: var(--bg-dark);
    color: var(--text-primary);
    min-height: 100vh;
    padding: 20px;
}

.app-container {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 24px;
}

/* Header */
.main-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-lg);
    padding: 18px 28px;
    box-shadow: var(--shadow-glow);
}

.logo {
    display: flex;
    align-items: center;
    gap: 16px;
}

.logo i {
    font-size: 2.2rem;
    color: var(--accent-blue);
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 10px;
}

.badge {
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
    font-size: 0.75rem;
    padding: 3px 10px;
    border-radius: 20px;
    color: #fff;
    font-weight: 600;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-top: 2px;
}

.author-tag {
    background: rgba(56, 189, 248, 0.1);
    color: var(--accent-blue);
    border: 1px solid rgba(56, 189, 248, 0.2);
    padding: 8px 16px;
    border-radius: 30px;
    font-weight: 500;
    font-size: 0.9rem;
}

/* Workspace */
.workspace {
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: 24px;
}

@media (max-width: 992px) {
    .workspace {
        grid-template-columns: 1fr;
    }
}

.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-lg);
    padding: 22px;
}

/* Control Panel */
.control-panel {
    display: flex;
    flex-direction: column;
    gap: 18px;
}

.control-panel h2 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    border-bottom: 1px solid var(--card-border);
    padding-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.highlight-box {
    background: rgba(56, 189, 248, 0.08);
    border: 1px solid rgba(56, 189, 248, 0.25);
    padding: 12px;
    border-radius: var(--radius-md);
}

.target-field {
    font-size: 1.1rem !important;
    font-weight: 700 !important;
    color: var(--accent-blue) !important;
    text-align: center;
}

.control-group label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 6px;
}

.label-with-value {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.badge-value {
    background: rgba(255, 255, 255, 0.08);
    padding: 2px 8px;
    border-radius: 6px;
    font-size: 0.8rem;
    color: var(--accent-blue);
    font-family: 'Fira Code', monospace;
}

.custom-select, .custom-input {
    width: 100%;
    background: #0f172a;
    border: 1px solid var(--card-border);
    color: var(--text-primary);
    padding: 10px 14px;
    border-radius: var(--radius-md);
    font-size: 0.9rem;
    outline: none;
    transition: border-color 0.2s;
}

.custom-select:focus, .custom-input:focus {
    border-color: var(--accent-blue);
}

.input-with-button {
    display: flex;
    gap: 8px;
}

.toggle-group {
    display: flex;
    background: #0f172a;
    border-radius: var(--radius-md);
    padding: 4px;
    border: 1px solid var(--card-border);
}

.toggle-btn {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 8px;
    font-size: 0.8rem;
    font-weight: 600;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s;
}

.toggle-btn.active {
    background: var(--accent-blue);
    color: #0f172a;
}

.help-text {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.text-warning {
    color: var(--accent-yellow) !important;
}

.slider {
    width: 100%;
    accent-color: var(--accent-blue);
    cursor: pointer;
}

/* Action Buttons */
.action-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    margin-top: 4px;
}

.btn {
    padding: 10px 14px;
    border-radius: var(--radius-md);
    border: none;
    font-weight: 600;
    font-size: 0.875rem;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all 0.2s ease;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary { background: var(--accent-blue); color: #0f172a; }
.btn-primary:hover:not(:disabled) { background: #0284c7; color: #fff; }

.btn-secondary { background: rgba(255, 255, 255, 0.08); color: var(--text-primary); border: 1px solid var(--card-border); }
.btn-secondary:hover:not(:disabled) { background: rgba(255, 255, 255, 0.15); }

.btn-warning { background: var(--accent-yellow); color: #0f172a; }
.btn-warning:hover:not(:disabled) { background: #d97706; color: #fff; }

.btn-danger { background: rgba(239, 68, 68, 0.15); color: var(--accent-red); border: 1px solid rgba(239, 68, 68, 0.3); }
.btn-danger:hover:not(:disabled) { background: var(--accent-red); color: #fff; }

/* Metrics */
.metrics-card {
    background: rgba(15, 23, 42, 0.6);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-md);
    padding: 14px;
}

.metrics-card h3 {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 6px;
}

.metrics-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
    text-align: center;
}

.metric-item { display: flex; flex-direction: column; }
.metric-label { font-size: 0.7rem; color: var(--text-secondary); }
.metric-value { font-size: 1.1rem; font-weight: 700; font-family: 'Fira Code', monospace; color: var(--accent-blue); }

.status-pending { color: var(--text-secondary); }
.status-found { color: var(--accent-green); }
.status-notfound { color: var(--accent-red); }

/* Display Area */
.display-area {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.visualizer-card {
    display: flex;
    flex-direction: column;
    min-height: 420px;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 20px;
    border-bottom: 1px solid var(--card-border);
    padding-bottom: 12px;
}

.card-header h2 { font-size: 1.25rem; font-weight: 700; }

.legend { display: flex; gap: 14px; flex-wrap: wrap; }
.legend-item { display: flex; align-items: center; gap: 6px; font-size: 0.8rem; color: var(--text-secondary); }
.color-box { width: 12px; height: 12px; border-radius: 3px; }

.color-box.default { background: #334155; }
.color-box.checking { background: var(--accent-yellow); }
.color-box.range { background: var(--accent-purple); }
.color-box.eliminated { background: #1e293b; border: 1px solid var(--accent-red); }
.color-box.found { background: var(--accent-green); }

/* Visualizer Boxes Container */
.visualizer-container {
    flex-grow: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    flex-wrap: wrap;
    padding: 24px 16px;
    background: #0b1120;
    border-radius: var(--radius-md);
    border: 1px dashed var(--card-border);
    min-height: 250px;
}

.element-box {
    width: 55px;
    height: 65px;
    background: #1e293b;
    border: 2px solid var(--card-border);
    border-radius: 10px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    position: relative;
    transition: all 0.25s ease;
    user-select: none;
}

.element-val {
    font-size: 1.15rem;
    font-weight: 700;
    font-family: 'Fira Code', monospace;
    color: var(--text-primary);
}

.element-idx {
    font-size: 0.65rem;
    color: var(--text-secondary);
    font-family: 'Fira Code', monospace;
    position: absolute;
    bottom: 3px;
}

/* Box States */
.element-box.checking {
    background: var(--accent-yellow) !important;
    border-color: var(--accent-yellow) !important;
    box-shadow: 0 0 15px var(--accent-yellow);
    transform: translateY(-8px) scale(1.1);
}
.element-box.checking .element-val { color: #0f172a; }

.element-box.range {
    background: rgba(168, 85, 247, 0.2) !important;
    border-color: var(--accent-purple) !important;
    box-shadow: 0 0 10px rgba(168, 85, 247, 0.4);
}

.element-box.eliminated {
    opacity: 0.35;
    background: #0f172a !important;
    border-color: var(--accent-red) !important;
    transform: scale(0.92);
}

.element-box.found {
    background: var(--accent-green) !important;
    border-color: var(--accent-green) !important;
    box-shadow: 0 0 20px var(--accent-green);
    transform: translateY(-10px) scale(1.15);
}
.element-box.found .element-val { color: #0f172a; }

.pointer-tag {
    position: absolute;
    top: -24px;
    font-size: 0.7rem;
    font-weight: 700;
    padding: 2px 6px;
    border-radius: 4px;
    font-family: 'Fira Code', monospace;
    text-transform: uppercase;
}
.pointer-low { background: var(--accent-purple); color: #fff; }
.pointer-mid { background: var(--accent-yellow); color: #0f172a; }
.pointer-high { background: var(--accent-pink); color: #fff; }

.status-message {
    margin-top: 16px;
    font-size: 0.95rem;
    color: var(--text-secondary);
    text-align: center;
    font-style: italic;
}

/* Info Grid */
.info-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

@media (max-width: 1200px) {
    .info-grid { grid-template-columns: 1fr; }
}

.info-card h2, .code-card h2, .complexity-card h2 {
    font-size: 1.05rem;
    margin-bottom: 12px;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 8px;
}

.info-content { color: var(--text-secondary); font-size: 0.9rem; line-height: 1.6; }
.info-content p { margin-bottom: 10px; }
.info-content ul { margin-left: 20px; margin-bottom: 10px; }

.code-card pre {
    background: #0b1120;
    padding: 14px;
    border-radius: var(--radius-md);
    overflow-x: auto;
    border: 1px solid var(--card-border);
}

.code-card code { font-family: 'Fira Code', monospace; font-size: 0.85rem; color: #e2e8f0; }

.complexity-table { width: 100%; border-collapse: collapse; margin-top: 8px; }
.complexity-table th, .complexity-table td {
    padding: 10px 12px;
    text-align: left;
    border-bottom: 1px solid var(--card-border);
    font-size: 0.875rem;
}
.complexity-table th { color: var(--text-secondary); font-weight: 500; }
.complexity-table td code {
    font-family: 'Fira Code', monospace;
    background: rgba(56, 189, 248, 0.1);
    color: var(--accent-blue);
    padding: 2px 6px;
    border-radius: 4px;
}

.badge-prereq {
    background: rgba(234, 179, 8, 0.15);
    color: var(--accent-yellow);
    padding: 3px 8px;
    border-radius: 6px;
    font-size: 0.8rem;
    font-weight: 600;
}

.main-footer {
    text-align: center;
    padding: 16px;
    color: var(--text-secondary);
    font-size: 0.85rem;
    border-top: 1px solid var(--card-border);
}