:root {
    --bg-color: #050811;
    --grid-color: rgba(56, 189, 248, 0.07);
    --card-bg: rgba(13, 22, 41, 0.75);
    --card-border: rgba(56, 189, 248, 0.2);
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --accent-cyan: #38bdf8;
    --accent-purple: #c084fc;
    --accent-emerald: #34d399;
    --accent-amber: #fbbf24;
    --accent-rose: #fb7185;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Fira Code', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, monospace;
}

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    min-height: 100vh;
    overflow: hidden;
    position: relative;
    background-image:
        radial-gradient(circle at 50% 50%, rgba(15, 23, 42, 0.8) 0%, var(--bg-color) 100%),
        linear-gradient(to right, var(--grid-color) 1px, transparent 1px),
        linear-gradient(to bottom, var(--grid-color) 1px, transparent 1px);
    background-size: 100% 100%, 50px 50px, 50px 50px;
}

header {
    position: absolute;
    top: 24px;
    left: 24px;
    z-index: 10;
    pointer-events: none;
}

header h1 {
    font-size: 1.4rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, #38bdf8, #a855f7);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 0 30px rgba(56, 189, 248, 0.3);
}

header p {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 4px;
}

.controls {
    position: absolute;
    top: 24px;
    right: 24px;
    z-index: 10;
}

.lang-btn {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    color: var(--text-main);
    padding: 8px 16px;
    border-radius: 8px;
    font-size: 0.85rem;
    cursor: pointer;
    backdrop-filter: blur(10px);
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 6px;
}

.lang-btn:hover {
    border-color: var(--accent-cyan);
    box-shadow: 0 0 15px rgba(56, 189, 248, 0.3);
}

#canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
}

#nodes-container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 2;
    pointer-events: none;
}

.node {
    position: absolute;
    transform: translate(-50%, -50%);
    padding: 12px 20px;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 30px;
    color: var(--text-main);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    pointer-events: auto;
    backdrop-filter: blur(12px);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.5), inset 0 1px 1px rgba(255, 255, 255, 0.1);
    display: flex;
    align-items: center;
    gap: 10px;
    user-select: none;
    will-change: transform, left, top;
    transition: border-color 0.3s, box-shadow 0.3s;
    white-space: nowrap;
}

.node:hover {
    border-color: var(--node-color, var(--accent-cyan));
    box-shadow: 0 0 25px var(--node-color, var(--accent-cyan));
}

.node-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background-color: var(--node-color, var(--accent-cyan));
    box-shadow: 0 0 10px var(--node-color, var(--accent-cyan));
    flex-shrink: 0;
}

.node.core {
    font-size: 1.05rem;
    padding: 16px 28px;
    border-width: 2px;
}

/* Drawer */
.drawer {
    position: fixed;
    top: 0;
    right: -450px;
    width: 420px;
    height: 100%;
    background: rgba(10, 16, 31, 0.92);
    border-left: 1px solid var(--card-border);
    backdrop-filter: blur(20px);
    z-index: 100;
    padding: 36px 30px;
    transition: right 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    box-shadow: -15px 0 40px rgba(0, 0, 0, 0.7);
    display: flex;
    flex-direction: column;
}

.drawer.active {
    right: 0;
}

.drawer-close {
    position: absolute;
    top: 24px;
    right: 24px;
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 1.5rem;
    cursor: pointer;
    transition: color 0.2s;
}

.drawer-close:hover {
    color: var(--text-main);
}

.drawer-tag {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    color: var(--drawer-color, var(--accent-cyan));
    font-weight: 700;
    margin-bottom: 10px;
}

.drawer-title {
    font-size: 1.35rem;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--text-main);
}

.drawer-body {
    font-size: 0.9rem;
    line-height: 1.65;
    color: var(--text-muted);
    flex-grow: 1;
    overflow-y: auto;
}

.drawer-body p {
    margin-bottom: 14px;
}

.drawer-body ul {
    margin-left: 18px;
    margin-bottom: 14px;
}

.drawer-body li {
    margin-bottom: 8px;
}

/* ===== Mobile responsiveness ===== */
@media (max-width: 640px) {
    header {
        top: 16px;
        left: 16px;
    }

    header h1 {
        font-size: 1.05rem;
    }

    header p {
        font-size: 0.7rem;
    }

    .controls {
        top: 16px;
        right: 16px;
    }

    .lang-btn {
        padding: 6px 12px;
        font-size: 0.75rem;
    }

    .node {
        padding: 8px 14px;
        font-size: 0.7rem;
        gap: 6px;
        border-radius: 20px;
    }

    .node-dot {
        width: 6px;
        height: 6px;
    }

    .node.core {
        font-size: 0.85rem;
        padding: 10px 18px;
    }

    .drawer {
        width: 100%;
        right: -100%;
        padding: 28px 20px 20px;
    }

    .drawer-title {
        font-size: 1.1rem;
    }

    .drawer-body {
        font-size: 0.85rem;
    }
}

@media (max-width: 380px) {
    header h1 {
        font-size: 0.95rem;
    }

    .node {
        padding: 6px 11px;
        font-size: 0.62rem;
    }

    .node.core {
        font-size: 0.75rem;
        padding: 9px 16px;
    }
}