/* Base styles and CSS variables */

:root {
    --bitcoin-orange: #f7931a;
    --bg-primary: #1e2139;
    --bg-secondary: #252945;
    --bg-card: #081d3a;
    --text-primary: #ffffff;
    --text-secondary: #a0a3bd;
    --success: #4ade80;
    --error: #f87171;
    --border-color: rgba(255, 255, 255, 0.08);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.3);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    padding: 1rem;
    line-height: 1.6;
}

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

header {
    text-align: center;
    padding: 2.5rem 0 1.5rem;
    margin-bottom: 2rem;
}

h1 {
    font-size: 2.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    font-weight: 700;
    letter-spacing: -0.02em;
}

h1 .bitcoin-icon {
    color: var(--bitcoin-orange);
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 400;
}

.card {
    background: var(--bg-card);
    border-radius: 1.25rem;
    padding: 2rem;
    margin-bottom: 1.25rem;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-md);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn {
    display: inline-block;
    padding: 1rem 1.75rem;
    background: var(--bitcoin-orange);
    color: white;
    text-decoration: none;
    border-radius: 0.75rem;
    border: none;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all 0.2s ease;
    width: 100%;
    text-align: center;
    box-shadow: var(--shadow-sm);
    letter-spacing: 0.01em;
}

.btn:hover {
    background: #e08610;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn:active {
    transform: translateY(0);
    box-shadow: var(--shadow-sm);
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.15);
}

/* Footer */
.footer {
    text-align: center;
    padding: 2rem 0 1rem;
    margin-top: 3rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.footer p {
    margin: 0;
}

.footer a {
    color: #ffa940;
    text-decoration: none;
    transition: all 0.2s ease;
    font-weight: 500;
}

.footer a:hover {
    color: #ffbb66;
    text-decoration: underline;
}

/* Mobile-first responsive design */
@media (max-width: 640px) {
    h1 {
        font-size: 1.875rem;
    }
    
    .card {
        padding: 1.5rem;
    }
    
    header {
        padding: 1.5rem 0 1rem;
    }
    
    .footer {
        padding: 1.5rem 0 0.75rem;
        margin-top: 2rem;
    }
}

@media (min-width: 641px) {
    body {
        padding: 1.5rem;
    }
}

@media (min-width: 768px) {
    body {
        padding: 2.5rem;
    }
}