:root {
    --color-bg: #ffffff;
    --color-text: #1a1a1a;
    --color-muted: #666666;
    --color-border: #e5e5e5;
    --color-accent: #0066cc;
    --color-accent-hover: #004999;
    --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, sans-serif;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
    font-family: var(--font-stack);
    color: var(--color-text);
    background: var(--color-bg);
    line-height: 1.6;
}

.container {
    max-width: 720px;
    margin: 0 auto;
    padding: 48px 24px;
}

header {
    margin-bottom: 32px;
    padding-bottom: 24px;
    border-bottom: 1px solid var(--color-border);
}

.back-link {
    color: var(--color-muted);
    text-decoration: none;
    font-size: 0.9rem;
    display: inline-block;
    margin-bottom: 16px;
}

.back-link:hover {
    color: var(--color-accent);
}

h1 {
    font-size: 2rem;
    margin: 0 0 8px 0;
    font-weight: 600;
}

h2 {
    font-size: 1.25rem;
    margin: 0 0 16px 0;
    font-weight: 600;
}

.subtitle {
    color: var(--color-muted);
    margin: 0;
}

.btn {
    background: var(--color-accent);
    color: #ffffff;
    border: none;
    padding: 10px 20px;
    font-size: 1rem;
    font-family: var(--font-stack);
    border-radius: 6px;
    cursor: pointer;
    transition: background-color 0.15s ease;
}

.btn:hover {
    background: var(--color-accent-hover);
}

.message {
    margin-top: 16px;
    color: var(--color-muted);
    min-height: 1.6em;
}