@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;700&family=Outfit:wght@400;600;700;800&display=swap');

:root {
    --bg: #020617;
    --panel: rgba(15, 23, 42, .8);
    --border: rgba(255, 255, 255, .07);
    --amber: #f59e0b;
    --blue: #3b82f6;
    --cyan: #22d3ee;
    --green: #4ade80;
    --purple: #a855f7;
    --red: #f87171;
    --text: #f8fafc;
    --muted: #64748b
}

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

html,
body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    background: #020617;
    font-family: 'Outfit', sans-serif;
    overscroll-behavior: none;
    touch-action: none;
    /* Disable browser defaults for panning */
}

#phet-stage {
    position: absolute;
    top: 0;
    left: 0;
    width: 1280px;
    height: 720px;
    background: #020617;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    transform-origin: 0 0;
    /* Updated for custom pan/zoom math */
    box-shadow: 0 0 50px rgba(0, 0, 0, 0.5);
    touch-action: none;
}

body.sim-page {
    font-family: 'Outfit', sans-serif;
    background: var(--bg);
    color: var(--text);
}

/* NAV */
.bst-nav {
    position: relative !important;
    width: 100%;
    z-index: 200;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: .55rem 1.5rem;
    background: rgba(15, 23, 42, 0.92);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    flex-shrink: 0;
}

.logo {
    font-size: 1rem;
    font-weight: 800
}

.nav-crumb {
    font-size: .78rem;
    color: #94a3b8;
    display: flex;
    align-items: center;
    gap: .4rem
}

.nav-crumb span {
    opacity: .3
}

.nav-crumb strong {
    color: var(--text)
}

.info-nav-btn {
    background: linear-gradient(135deg, rgba(245, 158, 11, .15), rgba(59, 130, 246, .1));
    border: 1px solid rgba(245, 158, 11, .35);
    color: var(--amber);
    padding: .35rem 1rem;
    border-radius: 50px;
    font-size: .8rem;
    font-weight: 700;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: .4rem;
    transition: .2s;
    font-family: inherit
}

.info-nav-btn:hover {
    background: var(--amber);
    color: #020617;
    transform: translateY(-1px)
}

.back-btn {
    border-radius: 50px;
    padding: .35rem 1rem;
    font-size: .8rem;
    color: #94a3b8;
    border: 1px solid rgba(255, 255, 255, .1);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: .4rem;
    transition: .2s
}

.back-btn:hover {
    border-color: var(--amber);
    color: var(--amber)
}

/* MAIN */
.bst-main {
    padding: 10px 14px 20px;
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: .6rem;
    width: 100%;
    min-height: 0;
    overflow: hidden;
}

.analogy-banner {
    background: linear-gradient(135deg, rgba(74, 222, 128, .07), rgba(34, 211, 238, .05));
    border: 1px solid rgba(74, 222, 128, .2);
    border-radius: 14px;
    padding: .55rem 1rem;
    display: flex;
    align-items: center;
    gap: .7rem;
    flex-wrap: wrap
}

.banner-icons {
    font-size: 1.3rem;
    flex-shrink: 0;
    letter-spacing: .15rem
}

.banner-text {
    flex: 1;
    font-size: .78rem;
    color: #cbd5e1;
    line-height: 1.45;
    min-width: 200px
}

.banner-text strong {
    color: var(--text)
}

.speed-row {
    display: flex;
    align-items: center;
    gap: .5rem;
    flex-shrink: 0
}

.mode-lbl {
    font-size: .67rem;
    font-weight: 700;
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: .5px
}

.mode-toggle {
    display: flex;
    background: rgba(15, 23, 42, .6);
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden
}

.mt-btn {
    background: transparent;
    border: none;
    color: var(--muted);
    padding: .24rem .6rem;
    font-size: .75rem;
    font-weight: 700;
    cursor: pointer;
    transition: .2s;
    font-family: inherit
}

.mt-btn:hover {
    color: var(--text)
}

.mt-btn.active {
    background: var(--green);
    color: #020617
}

/* LAYOUT */
.bst-layout {
    display: grid;
    grid-template-columns: 1fr 260px;
    gap: .65rem;
    align-items: stretch;
    flex: 1;
    min-height: 0;
}

/* CANVAS */
.tree-canvas-wrap {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 16px;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    backdrop-filter: blur(10px)
}

.canvas-topbar {
    display: flex;
    gap: 1.2rem;
    padding: .45rem 1rem;
    border-bottom: 1px solid var(--border);
    background: rgba(15, 23, 42, .4)
}

.canvas-stat {
    font-size: .72rem;
    color: var(--muted)
}

.canvas-stat strong {
    color: var(--text);
    font-family: 'JetBrains Mono', monospace
}

.svg-wrapper {
    position: relative;
    flex: 1;
    min-height: 440px
}

#tree-svg {
    display: block;
    width: 100%;
    height: 100%
}

.empty-tree-msg {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--muted);
    font-size: .85rem;
    gap: .3rem;
    pointer-events: none
}

.empty-icon {
    font-size: 2.5rem;
    opacity: .4
}

/* Traversal ribbon */
.traversal-ribbon {
    display: flex;
    align-items: center;
    gap: .5rem;
    padding: .4rem .8rem;
    border-top: 1px solid var(--border);
    background: rgba(15, 23, 42, .5);
    flex-wrap: wrap;
    min-height: 38px
}

.ribbon-label {
    font-size: .68rem;
    font-weight: 800;
    color: var(--cyan);
    text-transform: uppercase;
    letter-spacing: .5px;
    flex-shrink: 0
}

.ribbon-values {
    display: flex;
    gap: .25rem;
    flex-wrap: wrap
}

.rv-item {
    font-family: 'JetBrains Mono', monospace;
    font-size: .72rem;
    font-weight: 700;
    padding: .18rem .45rem;
    border-radius: 6px;
    background: rgba(34, 211, 238, .1);
    border: 1px solid rgba(34, 211, 238, .25);
    color: var(--cyan);
    transition: all .3s;
    opacity: .3
}

.rv-item.done {
    opacity: 1;
    background: rgba(34, 211, 238, .2);
    box-shadow: 0 0 6px rgba(34, 211, 238, .3)
}

.rv-item.current {
    opacity: 1;
    background: rgba(245, 158, 11, .25);
    border-color: var(--amber);
    color: var(--amber);
    box-shadow: 0 0 8px rgba(245, 158, 11, .4);
    transform: scale(1.1)
}

/* SVG node states */
.bst-node-circle {
    transition: all .4s
}

.bst-node-circle.state-default {
    fill: rgba(30, 41, 59, .9);
    stroke: #475569;
    stroke-width: 2px
}

.bst-node-circle.state-visiting {
    fill: rgba(245, 158, 11, .3);
    stroke: var(--amber);
    stroke-width: 2.5px
}

.bst-node-circle.state-found {
    fill: rgba(74, 222, 128, .25);
    stroke: var(--green);
    stroke-width: 2.5px
}

.bst-node-circle.state-notfound {
    fill: rgba(248, 113, 113, .2);
    stroke: var(--red);
    stroke-width: 2px
}

.bst-node-circle.state-deleting {
    fill: rgba(248, 113, 113, .3);
    stroke: var(--red);
    stroke-width: 2.5px
}

.bst-node-circle.state-inserting {
    fill: rgba(74, 222, 128, .3);
    stroke: var(--green);
    stroke-width: 2.5px;
    animation: pulse-node .5s ease-in-out 3
}

.bst-node-circle.state-traversed {
    fill: rgba(34, 211, 238, .2);
    stroke: var(--cyan);
    stroke-width: 2px
}

.bst-node-circle.state-successor {
    fill: rgba(168, 85, 247, .25);
    stroke: var(--purple);
    stroke-width: 2.5px
}

@keyframes pulse-node {

    0%,
    100% {
        filter: drop-shadow(0 0 4px transparent)
    }

    50% {
        filter: drop-shadow(0 0 12px currentColor)
    }
}

.bst-edge {
    stroke: rgba(100, 116, 139, .4);
    stroke-width: 1.5px;
    fill: none;
    transition: all .4s
}

.bst-edge.hl {
    stroke: var(--amber);
    stroke-width: 2px
}

.bst-edge.found {
    stroke: var(--green);
    stroke-width: 2px
}

/* SIDEBAR */
.bst-sidebar {
    display: flex;
    flex-direction: column;
    gap: .5rem;
    height: 100%;
    overflow-y: auto;
    touch-action: pan-y;
}

.bst-sidebar::-webkit-scrollbar {
    width: 2px
}

.bst-sidebar::-webkit-scrollbar-thumb {
    background: #334155
}

.ctrl-group {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: .7rem .8rem;
    backdrop-filter: blur(10px);
    display: flex;
    flex-direction: column;
    gap: .4rem
}

.ctrl-group-title {
    font-size: .72rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: .7px;
    color: var(--muted);
    display: flex;
    align-items: center;
    gap: .35rem
}

.ctrl-input-row {
    display: flex;
    gap: .35rem
}

.bst-input {
    flex: 1;
    background: rgba(15, 23, 42, .7);
    border: 1px solid rgba(255, 255, 255, .1);
    color: var(--text);
    padding: .35rem .65rem;
    border-radius: 8px;
    font-size: .88rem;
    font-family: 'JetBrains Mono', monospace;
    font-weight: 700;
    outline: none;
    transition: .2s
}

.bst-input:focus {
    border-color: var(--amber);
    box-shadow: 0 0 0 2px rgba(245, 158, 11, .12)
}

.bst-btn {
    display: flex;
    align-items: center;
    gap: .35rem;
    padding: .35rem .75rem;
    border-radius: 8px;
    font-size: .78rem;
    font-weight: 700;
    cursor: pointer;
    border: none;
    font-family: inherit;
    transition: all .2s;
    white-space: nowrap;
    flex-shrink: 0
}

.bst-btn.green {
    background: rgba(74, 222, 128, .15);
    color: var(--green);
    border: 1px solid rgba(74, 222, 128, .3)
}

.bst-btn.green:hover {
    background: var(--green);
    color: #020617
}

.bst-btn.amber {
    background: rgba(245, 158, 11, .12);
    color: var(--amber);
    border: 1px solid rgba(245, 158, 11, .3)
}

.bst-btn.amber:hover {
    background: var(--amber);
    color: #020617
}

.bst-btn.red {
    background: rgba(248, 113, 113, .12);
    color: var(--red);
    border: 1px solid rgba(248, 113, 113, .3)
}

.bst-btn.red:hover {
    background: var(--red);
    color: #fff
}

.bst-btn.danger {
    background: rgba(100, 116, 139, .1);
    color: var(--muted);
    border: 1px solid rgba(100, 116, 139, .2)
}

.bst-btn.danger:hover {
    background: rgba(248, 113, 113, .1);
    color: var(--red);
    border-color: rgba(248, 113, 113, .3)
}

.full-width {
    width: 100%;
    justify-content: center
}

.preset-label {
    font-size: .62rem;
    color: var(--muted);
    font-weight: 700
}

.preset-pills {
    display: flex;
    gap: .3rem;
    flex-wrap: wrap
}

.preset-pill {
    background: rgba(59, 130, 246, .1);
    border: 1px solid rgba(59, 130, 246, .25);
    color: var(--blue);
    padding: .18rem .55rem;
    border-radius: 20px;
    font-size: .7rem;
    font-weight: 700;
    cursor: pointer;
    transition: .2s;
    font-family: inherit
}

.preset-pill:hover {
    background: var(--blue);
    color: #fff
}

.traversal-btns {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: .3rem
}

.trav-btn {
    background: rgba(34, 211, 238, .08);
    border: 1px solid rgba(34, 211, 238, .2);
    color: var(--cyan);
    padding: .28rem .5rem;
    border-radius: 7px;
    font-size: .72rem;
    font-weight: 700;
    cursor: pointer;
    transition: .2s;
    font-family: inherit;
    text-align: center
}

.trav-btn:hover {
    background: var(--cyan);
    color: #020617
}

/* STEP PANEL */
.step-panel {
    background: linear-gradient(135deg, rgba(15, 23, 42, .8), rgba(30, 41, 59, .6));
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: .7rem .8rem
}

.step-panel-header {
    display: flex;
    align-items: center;
    gap: .45rem;
    margin-bottom: .3rem
}

.step-icon {
    font-size: 1.1rem
}

.step-title {
    font-size: .82rem;
    font-weight: 800;
    color: var(--text)
}

.step-desc {
    font-size: .75rem;
    color: #94a3b8;
    line-height: 1.55
}

.step-result {
    margin-top: .4rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: .73rem;
    padding: .3rem .55rem;
    border-radius: 6px
}

.step-result.ok {
    background: rgba(74, 222, 128, .1);
    color: var(--green);
    border: 1px solid rgba(74, 222, 128, .2)
}

.step-result.err {
    background: rgba(248, 113, 113, .1);
    color: var(--red);
    border: 1px solid rgba(248, 113, 113, .2)
}

.step-result.info {
    background: rgba(34, 211, 238, .08);
    color: var(--cyan);
    border: 1px solid rgba(34, 211, 238, .2)
}

/* PROPERTY CARD */
.property-card {
    background: linear-gradient(135deg, rgba(74, 222, 128, .06), rgba(34, 211, 238, .04));
    border: 1px solid rgba(74, 222, 128, .18);
    border-radius: 12px;
    padding: .65rem .75rem
}

.prop-title {
    font-size: .7rem;
    font-weight: 800;
    color: var(--green);
    text-transform: uppercase;
    letter-spacing: .7px;
    margin-bottom: .4rem
}

.prop-rule {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: .35rem;
    flex-wrap: wrap;
    margin-bottom: .4rem
}

.prop-left {
    background: rgba(248, 113, 113, .12);
    color: #fca5a5;
    border: 1px solid rgba(248, 113, 113, .25);
    padding: .18rem .5rem;
    border-radius: 6px;
    font-size: .68rem;
    font-weight: 700
}

.prop-op {
    font-size: 1rem;
    font-weight: 900;
    color: var(--muted)
}

.prop-root {
    background: rgba(34, 211, 238, .15);
    color: var(--cyan);
    border: 1px solid rgba(34, 211, 238, .3);
    padding: .18rem .55rem;
    border-radius: 6px;
    font-size: .72rem;
    font-weight: 800
}

.prop-right {
    background: rgba(74, 222, 128, .12);
    color: var(--green);
    border: 1px solid rgba(74, 222, 128, .25);
    padding: .18rem .5rem;
    border-radius: 6px;
    font-size: .68rem;
    font-weight: 700
}

.prop-desc {
    font-size: .68rem;
    color: var(--muted);
    line-height: 1.5
}

/* INFO MODAL */
.info-modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(2, 6, 23, .85);
    backdrop-filter: blur(10px);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    animation: mfade .2s ease
}

.info-modal-overlay.hidden {
    display: none
}

@keyframes mfade {
    from {
        opacity: 0
    }

    to {
        opacity: 1
    }
}

.info-modal-box {
    background: linear-gradient(145deg, #1e293b, #0f172a);
    border: 1px solid rgba(74, 222, 128, .2);
    border-radius: 20px;
    padding: 1.4rem;
    width: 100%;
    max-width: 600px;
    max-height: 85vh;
    overflow-y: auto;
    position: relative;
    box-shadow: 0 30px 80px rgba(0, 0, 0, .7);
    animation: mslide .3s cubic-bezier(.175, .885, .32, 1.275)
}

@keyframes mslide {
    from {
        transform: translateY(25px);
        opacity: 0
    }

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

.info-modal-close {
    position: absolute;
    top: .85rem;
    right: .85rem;
    background: rgba(255, 255, 255, .05);
    border: 1px solid var(--border);
    color: var(--muted);
    width: 30px;
    height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: .2s;
    font-size: .78rem
}

.info-modal-close:hover {
    background: var(--red);
    color: #fff;
    border-color: var(--red)
}

.info-modal-header {
    display: flex;
    align-items: center;
    gap: .9rem;
    margin-bottom: .9rem
}

.info-modal-icon {
    font-size: 2rem
}

.info-modal-title {
    font-size: 1rem;
    font-weight: 800;
    color: var(--text)
}

.info-modal-subtitle {
    font-size: .7rem;
    color: var(--muted)
}

.why-tabs {
    display: flex;
    gap: .3rem;
    flex-wrap: wrap;
    margin-bottom: .8rem;
    border-bottom: 1px solid var(--border);
    padding-bottom: .45rem
}

.why-tab {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--muted);
    padding: .22rem .65rem;
    border-radius: 7px;
    font-size: .73rem;
    font-weight: 700;
    cursor: pointer;
    transition: .2s;
    font-family: inherit
}

.why-tab:hover {
    color: var(--green);
    border-color: var(--green)
}

.why-tab.active {
    background: var(--green);
    border-color: var(--green);
    color: #020617
}

.why-section {
    display: none
}

.why-section.active {
    display: block
}

.step-list {
    display: flex;
    flex-direction: column;
    gap: .45rem;
    margin: .3rem 0
}

.step-item {
    display: flex;
    align-items: flex-start;
    gap: .5rem;
    font-size: .78rem;
    color: #94a3b8;
    line-height: 1.55
}

.step-item em {
    color: var(--amber);
    font-style: normal
}

.step-item strong {
    color: var(--text)
}

.step-num {
    background: rgba(74, 222, 128, .13);
    color: var(--green);
    border-radius: 50%;
    width: 24px;
    height: 24px;
    min-width: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: .65rem;
    font-weight: 800
}