src/App.svelte

<script lang="ts">
  import { onMount } from 'svelte';

  let loading = true;
  let error: string | null = null;
  let stats = {
    revenue: 0,
    users: 0,
    orders: 0,
    conversion: 0
  };

  onMount(async () => {
    try {
      await new Promise(resolve => setTimeout(resolve, 1000));
      stats = {
        revenue: 124500,
        users: 2341,
        orders: 342,
        conversion: 3.2
      };
      loading = false;
    } catch (err) {
      error = 'Failed to load dashboard data';
      loading = false;
    }
  });

  const formatCurrency = (amount: number) =>
    new Intl.NumberFormat('en-US', {
      style: 'currency',
      currency: 'USD',
      minimumFractionDigits: 0,
      maximumFractionDigits: 0
    }).format(amount);

  const formatNumber = (num: number) =>
    new Intl.NumberFormat('en-US').format(num);
</script>

<svelte:head>
  <style>
    :root {
      --primary: #3b82f6;
      --success: #10b981;
      --danger: #ef4444;
      --gray-50: #f9fafb;
      --gray-100: #f3f4f6;
      --gray-200: #e5e7eb;
      --gray-300: #d1d5db;
      --gray-400: #9ca3af;
      --gray-500: #6b7280;
      --gray-600: #4b5563;
      --gray-700: #374151;
      --gray-800: #1f2937;
      --gray-900: #111827;
    }

    * { box-sizing: border-box; }

    body {
      margin: 0;
      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
      background-color: var(--gray-50);
      color: var(--gray-900);
      line-height: 1.5;
    }

    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 2rem 1rem;
    }

    header { margin-bottom: 2rem; }

    h1 {
      margin: 0;
      font-size: 2rem;
      font-weight: 700;
      color: var(--gray-900);
    }

    .subtitle {
      margin: 0.25rem 0 0;
      color: var(--gray-600);
    }

    .grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
      gap: 1.5rem;
      margin-bottom: 2rem;
    }

    .loading, .error {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 400px;
      color: var(--gray-500);
    }

    .spinner {
      width: 40px;
      height: 40px;
      border: 4px solid var(--gray-200);
      border-top: 4px solid var(--primary);
      border-radius: 50%;
      animation: spin 1s linear infinite;
    }

    @keyframes spin {
      0% { transform: rotate(0deg); }
      100% { transform: rotate(360deg); }
    }

    .error { color: var(--danger); }

    .card {
      background: white;
      border-radius: 0.5rem;
      padding: 1.5rem;
      box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
      transition: box-shadow 0.15s;
    }

    .card:hover {
      box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    }

    .card-title {
      margin: 0 0 0.5rem;
      font-size: 0.875rem;
      font-weight: 500;
      color: var(--gray-600);
      text-transform: uppercase;
      letter-spacing: 0.05em;
    }

    .card-value {
      margin: 0;
      font-size: 1.875rem;
      font-weight: 700;
      color: var(--gray-900);
    }

    .card-change {
      margin-top: 0.5rem;
      font-size: 0.875rem;
      font-weight: 500;
    }

    .positive { color: var(--success); }
    .negative { color: var(--danger); }

    .chart-section {
      background: white;
      border-radius: 0.5rem;
      padding: 1.5rem;
      box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    }

    .chart-section h2 {
      margin: 0 0 1rem;
      font-size: 1.25rem;
      font-weight: 600;
      color: var(--gray-900);
    }

    .chart-placeholder {
      width: 100%;
      height: 200px;
      background: var(--gray-100);
      border: 2px dashed var(--gray-300);
      border-radius: 0.5rem;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--gray-500);
      font-size: 1rem;
    }

    @media (max-width: 640px) {
      .container { padding: 1rem; }
      h1 { font-size: 1.5rem; }
      .grid { grid-template-columns: 1fr; }
    }
  </style>
</svelte:head>

<main class="container">
  <header>
    <h1>Dashboard</h1>
    <p class="subtitle">Overview of your business performance</p>
  </header>

  {#if loading}
    <div class="loading">
      <div class="spinner"></div>
      <p>Loading dashboard...</p>
    </div>
  {:else if error}
    <div class="error">
      <p>{error}</p>
    </div>
  {:else}
    <section class="grid">
      <div class="card">
        <h3 class="card-title">Revenue</h3>
        <p class="card-value">{formatCurrency(stats.revenue)}</p>
        <p class="card-change positive">+12.5%</p>
      </div>

      <div class="card">
        <h3 class="card-title">Active Users</h3>
        <p class="card-value">{formatNumber(stats.users)}</p>
        <p class="card-change positive">+5.2%</p>
      </div>

      <div class="card">
        <h3 class="card-title">Orders</h3>
        <p class="card-value">{formatNumber(stats.orders)}</p>
        <p class="card-change negative">-2.4%</p>
      </div>

      <div class="card">
        <h3 class="card-title">Conversion</h3>
        <p class="card-value">{stats.conversion}%</p>
        <p class="card-change positive">+0.3%</p>
      </div>
    </section>

    <section class="chart-section">
      <h2>Revenue Trend</h2>
      <div class="chart-placeholder">Chart placeholder</div>
    </section>
  {/if}
</main>