* {
    box-sizing: border-box;
}

:root {
    --bg: #f4f6f8;
    --surface: #ffffff;
    --surface-alt: #f8fafc;
    --border: #cfd5dc;
    --border-dark: #aeb6c0;
    --text: #20252b;
    --muted: #69727d;
    --primary: #1976d2;
    --primary-light: #e7f1fc;
    --danger: #c94b4b;
    --line: #4c5968;
}

html,
body {
    margin: 0;
    width: 100%;
    height: 100%;
    font-family: Arial, Helvetica, sans-serif;
    color: var(--text);
    background: var(--bg);
}

body {
    min-width: 900px;
}

button {
    font-family: inherit;
}

.app {
    width: 100%;
    height: 100vh;
    min-height: 650px;
    margin: 0;
    display: flex;
    flex-direction: column;
    background: var(--surface);
    border: none;
    box-shadow: none;
    overflow: hidden;
}

/* =========================
   TOPBAR
   ========================= */

.topbar {
    height: 44px;
    display: flex;
    align-items: center;
    border-bottom: 1px solid var(--border);
    background: #f7f8fa;
    flex-shrink: 0;
}

.brand {
    height: 100%;
    display: flex;
    align-items: center;
    padding: 0 16px;
    font-size: 14px;
    font-weight: 600;
    border-right: 1px solid var(--border);
}

.brand-logo {
    width: 46px;
    height: 46px;
    object-fit: contain;
}

.menu {
    display: flex;
    height: 100%;
}

.menu-item {
    position: relative;
    height: 100%;
}

.menu > button,
.menu-item > .menu-button {
    height: 100%;
    min-width: 70px;
    padding: 0 16px;
    border: 0;
    border-right: 1px solid var(--border);
    background: transparent;
    color: var(--text);
    cursor: pointer;
    font-size: 13px;
}

.menu > button:hover,
.menu-item > .menu-button:hover,
.menu-item > .menu-button:focus-visible,
.dropdown-menu button:focus-visible {
    background: #e9edf1;
    outline: 0;
}

.menu-button[aria-expanded="true"] {
    background: #e9edf1;
}

.dropdown-menu {
    position: absolute;
    top: 43px;
    left: 0;
    z-index: 10;
    display: none;
    min-width: 150px;
    padding: 4px 0;
    border: 1px solid var(--border);
    background: #fff;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.14);
}

.dropdown-menu.open {
    display: block;
}

.dropdown-menu button {
    width: 100%;
    min-width: 0;
    height: 32px;
    padding: 0 14px;
    border: 0;
    background: #fff;
    color: var(--text);
    cursor: pointer;
    text-align: left;
    font-size: 12px;
}

.dropdown-menu button + button {
    border-top: 1px solid #f0f2f4;
}

.canvas.grid-hidden {
    background-image: none;
}

/* =========================
   WORKSPACE
   ========================= */

.workspace {
    flex: 1;
    min-height: 0;
    display: flex;
    flex-direction: column;
    background: #fff;
}

.workspace-header {
    height: 58px;
    padding: 10px 18px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid #e4e7eb;
    background: #fff;
}

.eyebrow {
    display: block;
    color: var(--primary);
    font-size: 9px;
    font-weight: 700;
    letter-spacing: 0.12em;
    margin-bottom: 3px;
}

h1 {
    margin: 0;
    font-size: 18px;
    font-weight: 600;
}

.topology-info {
    display: flex;
    gap: 18px;
    color: var(--muted);
    font-size: 11px;
}

/* =========================
   CANVAS
   ========================= */

.canvas {
    position: relative;
    flex: 1;
    overflow: hidden;
    user-select: none;
    background-color: #fff;

    background-image:
        linear-gradient(#edf0f3 1px, transparent 1px),
        linear-gradient(90deg, #edf0f3 1px, transparent 1px);

    background-size: 25px 25px;
}

.canvas.drag-over {
    background-color: #f8fbff;
    box-shadow: inset 0 0 0 2px #8bbcf0;
}

.links-layer {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1;
}

.selection-box {
    position: absolute;
    display: none;
    z-index: 4;
    border: 1px solid var(--primary);
    background: rgba(25, 118, 210, 0.1);
    pointer-events: none;
}

.link-line {
    stroke: var(--line);
    stroke-width: 2;
}

.link-line.selected {
    stroke: var(--primary);
    stroke-width: 3;
}

/* =========================
   EMPTY STATE
   ========================= */

.empty-state {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    color: #9aa3ad;
    pointer-events: none;
    text-align: center;
}

.empty-icon {
    width: 40px;
    height: 40px;
    margin-bottom: 10px;
    display: grid;
    place-items: center;
    border: 1px dashed #aeb6c0;
    border-radius: 6px;
    font-size: 22px;
}

.empty-state strong {
    color: #68727e;
    font-size: 13px;
    margin-bottom: 5px;
}

.empty-state span {
    font-size: 11px;
}

/* =========================
   NODES
   ========================= */

.network-node {
    position: absolute;
    z-index: 3;
    width: 72px;
    height: 62px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 4px;

    background: #fff;
    border: 1px solid #8e98a4;
    border-radius: 3px;

    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.12);
    cursor: grab;
    user-select: none;
}

.network-node:active {
    cursor: grabbing;
}

.network-node:hover {
    border-color: var(--primary);
}

.network-node.selected {
    border: 2px solid var(--primary);
    background: var(--primary-light);
}

.network-node.link-source {
    border: 2px solid #e3a72f;
    background: #fff9e9;
}

.node-symbol {
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.node-symbol svg {
    width: 26px;
    height: 26px;
    fill: none;
    stroke: currentColor;
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
}

.node-name {
    font-size: 10px;
    color: #4d5762;
}

.node-type {
    position: absolute;
    bottom: -16px;
    font-size: 9px;
    color: #8b949e;
}

/* Different symbols */
.node-host .node-symbol {
    color: #343c45;
}

.node-switch .node-symbol {
    color: #1976d2;
}

.node-controller .node-symbol {
    color: #6d55a8;
}

.node-router .node-symbol {
    color: #3d7d59;
}

.node-nat .node-symbol {
    color: #536170;
}

/* =========================
   BOTTOM PANEL
   ========================= */

.bottom-panel {
    height: 128px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    border-top: 1px solid var(--border-dark);
    background: #f7f8fa;
    flex-shrink: 0;
}

.panel-section {
    min-width: 0;
}

.components-section {
    border-right: 1px solid var(--border-dark);
}

.panel-title {
    height: 34px;
    display: flex;
    align-items: center;
    padding: 0 12px;
    border-bottom: 1px solid var(--border);
    font-size: 15px;
    font-weight: 500;
    background: #fff;
}

.component-list,
.actions-list {
    height: calc(100% - 34px);
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 9px 12px;
}

.component-tool,
.action-btn {
    height: 58px;
    min-width: 82px;
    padding: 6px 10px;

    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;

    border: 1px solid #b8c0c9;
    border-radius: 3px;
    background: #fff;

    color: #252b32;
    font-size: 10px;

    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}

.component-tool {
    cursor: grab;
}

.component-tool:hover,
.action-btn:hover {
    background: #f0f5fa;
    border-color: #8da5bb;
}

.component-tool:active {
    cursor: grabbing;
}

.component-icon {
    width: 26px;
    height: 26px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.component-icon svg {
    width: 24px;
    height: 24px;
    fill: none;
    stroke: currentColor;
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
}

.host-icon {
    color: #343c45;
}

.switch-icon {
    color: #1976d2;
}

.controller-icon {
    color: #6d55a8;
}

.router-icon {
    color: #3d7d59;
}

.nat-icon {
    color: #536170;
}

.action-btn {
    cursor: pointer;
    min-width: 110px;
}

.action-btn span {
    font-size: 17px;
}

.action-btn.active {
    background: #e7f1fc;
    border-color: var(--primary);
    color: #125fa8;
}

.action-btn.danger:hover {
    color: var(--danger);
    border-color: #d99797;
}

/* =========================
   MODE INDICATOR
   ========================= */

.mode-indicator {
    position: fixed;
    left: 50%;
    bottom: 22px;
    transform: translateX(-50%);

    display: flex;
    align-items: center;
    gap: 8px;

    padding: 8px 12px;
    background: #202830;
    color: #fff;
    border-radius: 4px;

    font-size: 11px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
    z-index: 20;
}

.mode-indicator.hidden {
    display: none;
}

.mode-dot {
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: #e3a72f;
}

.mode-indicator button {
    margin-left: 6px;
    border: 0;
    background: transparent;
    color: #a9cfff;
    cursor: pointer;
    font-size: 11px;
}

/* =========================
   TOAST
   ========================= */

.toast {
    position: fixed;
    right: 22px;
    bottom: 22px;
    padding: 10px 14px;
    background: #202830;
    color: #fff;
    border-radius: 4px;
    font-size: 11px;
    opacity: 0;
    transform: translateY(8px);
    pointer-events: none;
    transition: 0.2s ease;
    z-index: 30;
}

.toast.show {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 1050px) {
    body {
        min-width: 0;
    }

    .app {
        width: 100%;
        height: 100vh;
        min-height: 650px;
        margin: 0;
    }

    .bottom-panel {
        grid-template-columns: 1fr;
        height: auto;
    }

    .components-section {
        border-right: 0;
        border-bottom: 1px solid var(--border-dark);
    }

    .component-list,
    .actions-list {
        overflow-x: auto;
    }
}