:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-700: #374151;
    --gray-900: #111827;
    --red-500: #ef4444;
    --green-500: #22c55e;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--gray-100);
    color: var(--gray-900);
    line-height: 1.5;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem;
}

.card {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    margin-bottom: 1rem;
}

.btn {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
}

.btn:hover {
    background: var(--primary-dark);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-secondary {
    background: var(--gray-200);
    color: var(--gray-700);
}

.error {
    color: var(--red-500);
    padding: 1rem;
    background: #fef2f2;
    border-radius: 4px;
    margin-bottom: 1rem;
}

.success {
    color: var(--green-500);
    padding: 1rem;
    background: #f0fdf4;
    border-radius: 4px;
    margin-bottom: 1rem;
}

.loading {
    opacity: 0.7;
    pointer-events: none;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 1rem;
}