:root {
    /* Transitions */
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);

    /* Layout */
    --panel-width-left: 300px;
    --panel-width-right: 360px;
    --nav-height: 70px;
}

:root[data-theme="dark"] {
    --bg-dark: hsl(222, 47%, 7%);
    --bg-panel: hsl(222, 47%, 11%);
    --bg-card: hsla(222, 47%, 15%, 0.7);
    --accent-blue: hsl(217, 91%, 60%);
    --accent-yellow: hsl(45, 93%, 58%);
    --accent-green: hsl(160, 84%, 39%);
    --accent-red: hsl(0, 84%, 60%);
    --text-main: hsl(210, 40%, 98%);
    --text-dim: hsl(215, 20%, 75%);
    --border-color: hsla(217, 91%, 60%, 0.15);
    --shadow-premium: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 10px 10px -5px rgba(0, 0, 0, 0.2);
    --glass-bg: hsla(222, 47%, 11%, 0.8);
    --glass-border: hsla(217, 91%, 60%, 0.2);
}

:root[data-theme="light"] {
    --bg-dark: hsl(210, 40%, 98%);
    --bg-panel: hsl(0, 0%, 100%);
    --bg-card: hsla(0, 0%, 95%, 0.4);
    --accent-blue: hsl(221, 83%, 53%);
    --accent-yellow: hsl(38, 92%, 50%);
    --accent-green: hsl(142, 71%, 45%);
    --accent-red: hsl(0, 72%, 51%);
    --text-main: hsl(222, 47%, 12%);
    --text-dim: hsl(215, 16%, 35%);
    --border-color: hsla(221, 83%, 53%, 0.1);
    --shadow-premium: 0 10px 30px -5px rgba(0, 0, 0, 0.05), 0 5px 15px -5px rgba(0, 0, 0, 0.03);
    --glass-bg: hsla(0, 0%, 100%, 0.85);
    --glass-border: hsla(221, 83%, 53%, 0.15);
}

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

body {
    background-color: var(--bg-dark);
    color: var(--text-main);
    font-family: 'Outfit', 'Inter', sans-serif;
    height: 100vh;
    overflow-x: hidden;
    overflow-y: auto;
    /* Allow page-level scroll if containers fail */
}

.app-container {
    display: flex;
    flex-direction: column;
    height: 100%;
}

/* Top Nav */
.top-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
    height: var(--nav-height);
    background-color: var(--bg-panel);
    border-bottom: 2px solid var(--border-color);
    z-index: 100;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, #60a5fa, #3b82f6);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-controls {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.select-group {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.select-group label {
    font-size: 0.7rem;
    color: var(--text-dim);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

select {
    background-color: var(--bg-dark);
    color: var(--text-main);
    border: 1px solid var(--border-color);
    padding: 0.4rem 0.8rem;
    border-radius: 6px;
    font-family: inherit;
    outline: none;
}

/* Main Layout */
.main-content {
    display: grid;
    grid-template-columns: var(--panel-width-left) 1fr var(--panel-width-right);
    flex: 1;
    overflow-y: auto;
    /* Allow grid to overflow */
}

/* Panels */
aside {
    background-color: var(--bg-panel);
    display: flex;
    flex-direction: column;
    transition: var(--transition);
    position: relative;
    z-index: 10;
}

.left-panel {
    border-right: 1px solid var(--border-color);
}

.right-panel {
    border-left: 1px solid var(--border-color);
    overflow-y: auto;
    background: linear-gradient(to bottom, var(--bg-panel), var(--bg-dark));
}

.panel-header {
    padding: 1.5rem 1.25rem;
    font-weight: 800;
    font-size: 0.75rem;
    border-bottom: 1px solid var(--border-color);
    text-transform: uppercase;
    color: var(--accent-blue);
    letter-spacing: 0.15em;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Info Cards */
.info-sections {
    padding: 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.info-card {
    background-color: var(--bg-card);
    padding: 1.25rem;
    border-radius: 16px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-premium);
    backdrop-filter: blur(12px);
    transition: var(--transition);
}

.info-card h3 {
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
    color: var(--accent-blue);
}

.info-card p {
    font-size: 0.85rem;
    line-height: 1.5;
    color: var(--text-dim);
}

pre {
    background-color: var(--bg-dark);
    color: var(--text-main);
    padding: 0.75rem;
    border-radius: 8px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    overflow-x: auto;
    border: 1px solid var(--border-color);
}

.info-complexity {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
}

.complexity-item {
    background-color: var(--bg-card);
    padding: 0.75rem;
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
    border: 1px solid var(--border-color);
}

.complexity-item .label {
    font-size: 0.7rem;
    color: var(--text-dim);
}

.complexity-item span:not(.label) {
    font-weight: 700;
    color: var(--accent-yellow);
}

/* Buttons */
.btn-secondary {
    background: var(--bg-card);
    color: var(--text-main);
    border: 1px solid var(--border-color);
    padding: 0.6rem 1.2rem;
    border-radius: 8px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.btn-secondary:hover {
    border-color: var(--accent-blue);
    color: var(--accent-blue);
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.15);
}

.step-btn {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    width: 45px;
    height: 45px;
    border-radius: 50%;
    font-size: 1.1rem;
    color: var(--text-main);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-premium);
}

.step-btn:hover {
    background: var(--bg-panel);
    color: var(--accent-blue);
    transform: scale(1.1);
}

.play-btn {
    background: linear-gradient(135deg, var(--accent-blue), #60a5fa);
    border: none;
    width: 55px;
    height: 55px;
    border-radius: 50%;
    color: white;
    font-size: 1.3rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.4);
    transition: var(--transition);
}

.play-btn:hover {
    transform: scale(1.1) translateY(-2px);
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.6);
}

/* Inputs */
.control-row {
    display: flex;
    gap: 10px;
}

.control-row .input-group {
    flex: 1;
    margin-bottom: 0.8rem;
}

.input-group {
    margin-bottom: 1rem;
}

.input-group label {
    display: block;
    font-size: 0.8rem;
    margin-bottom: 0.4rem;
    color: var(--text-dim);
}

input[type="text"],
input[type="number"] {
    width: 100%;
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    padding: 0.6rem 0.8rem;
    border-radius: 8px;
    outline: none;
    transition: var(--transition);
    font-family: inherit;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.05);
}

input[type="text"]:focus,
input[type="number"]:focus {
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.2);
}

input[type="range"] {
    width: 120px;
    accent-color: var(--accent-blue);
}

/* Visualization Panel Layout */
.viz-panel {
    display: flex;
    flex-direction: column;
    position: relative;
    background-color: var(--bg-dark);
}

#visualization-area {
    flex: 1;
    position: relative;
    overflow-x: hidden;
    overflow-y: auto;
    background: radial-gradient(circle at center, var(--bg-panel) 0%, var(--bg-dark) 100%);
}

#main-svg {
    width: 100%;
    display: block;
    min-height: 100%;
    /* Ensure it fills at least the area */
}

/* SVG Elements Styling */
.graph-node {
    filter: drop-shadow(0px 4px 6px rgba(0, 0, 0, 0.3));
    transition: filter 0.3s ease;
}

.graph-node:hover {
    filter: drop-shadow(0px 6px 10px rgba(59, 130, 246, 0.5));
    cursor: pointer;
}

.graph-edge {
    stroke-linecap: round;
}

.playback-controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
    padding: 0.8rem 1.5rem;
    background: var(--glass-bg);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border: 1px solid var(--glass-border);
    position: absolute;
    bottom: 30px;
    right: 30px;
    width: auto;
    border-radius: 100px;
    box-shadow: 0 15px 35px -5px rgba(0, 0, 0, 0.2), var(--shadow-premium);
    pointer-events: auto;
    transition: var(--transition);
    border-top: 1px solid hsla(0, 0%, 100%, 0.1);
}

.playback-controls .step-btn {
    width: 38px;
    height: 38px;
    font-size: 1rem;
}

.playback-controls .play-btn {
    width: 48px;
    height: 48px;
    font-size: 1.2rem;
}

.playback-controls button {
    pointer-events: auto;
}

/* Panel Body */
.panel-body {
    padding: 1.25rem;
    flex: 1;
    overflow-y: auto;
}

/* Button groups */
.btn-group {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
    gap: 0.75rem;
    margin-bottom: 0.5rem;
}

/* Button variants */
.btn-primary,
.btn-danger,
.btn-info,
.btn-outline,
.btn-danger-outline {
    padding: 0.75rem 1rem;
    border-radius: 8px;
    font-family: inherit;
    font-weight: 600;
    font-size: 0.8rem;
    cursor: pointer;
    transition: var(--transition);
    border: none;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    position: relative;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1.2;
    min-height: 44px;
}

.btn-primary::after,
.btn-danger::after,
.btn-info::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(rgba(255, 255, 255, 0.1), transparent);
    pointer-events: none;
}

.btn-primary {
    background-color: var(--accent-blue);
    color: white;
}

.btn-primary:hover {
    background-color: #2563eb;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.4);
}

.btn-danger {
    background-color: var(--accent-red);
    color: white;
}

.btn-danger:hover {
    background-color: #dc2626;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(220, 38, 38, 0.4);
}

.btn-info {
    background-color: var(--accent-green);
    color: white;
}

.btn-info:hover {
    background-color: #059669;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(5, 150, 105, 0.4);
}

.btn-outline {
    background-color: transparent;
    border: 1px solid var(--accent-blue);
    color: var(--accent-blue);
}

.btn-outline:hover {
    background-color: var(--accent-blue);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);
}

.btn-danger-outline {
    background-color: transparent;
    border: 1px solid var(--accent-red);
    color: var(--accent-red);
}

.btn-danger-outline:hover {
    background-color: var(--accent-red);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(220, 38, 38, 0.2);
}

/* Theme toggle */
#theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    padding: 0;
}

/* Toast Alerts */
.toast-container {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 2000;
    display: flex;
    flex-direction: column;
    gap: 12px;
    pointer-events: none;
}

.toast {
    background-color: var(--glass-bg);
    color: var(--text-main);
    padding: 12px 20px;
    border-radius: 12px;
    box-shadow: var(--shadow-premium);
    backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    animation: slideIn 0.3s ease-out forwards;
    opacity: 0;
    font-weight: 500;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 12px;
    min-width: 250px;
    pointer-events: auto;
}

.toast-success i {
    color: var(--accent-green);
}

.toast-error i {
    color: var(--accent-red);
}

.toast-warning i {
    color: var(--accent-yellow);
}

.toast-info i {
    color: var(--accent-blue);
}

.toast-success {
    border-left: 4px solid var(--accent-green);
}

.toast-error {
    border-left: 4px solid var(--accent-red);
}

.toast-warning {
    border-left: 4px solid var(--accent-yellow);
}

.toast-info {
    border-left: 4px solid var(--accent-blue);
}


@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }

    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.toast.fade-out {
    animation: fadeOut 0.3s ease-out forwards;
}

@keyframes fadeOut {
    to {
        opacity: 0;
        transform: translateY(10px);
    }
}