/* Gumroad-style Design System */
:root {
    --color-bg: #ffffff;
    --color-text: #000000;
    --color-border: #000000;
    --color-primary: #000000;
    --color-accent-pink: #ff90e8;
    --color-accent-yellow: #ffc900;
    --color-accent-green: #00E054;
    --color-accent-blue: #2B4C7E;
    --color-gray-light: #f4f4f0;
    
    --border-width: 2px;
    --shadow-hard: 5px 5px 0px 0px var(--color-border);
    --shadow-hover: 2px 2px 0px 0px var(--color-border);
    
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --font-mono: 'JetBrains Mono', 'Courier New', Courier, monospace;
    
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 8rem;
}

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

body {
    font-family: var(--font-main);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: var(--spacing-sm);
    letter-spacing: -0.02em;
}

h1 { font-size: 3.5rem; }
h2 { font-size: 2.5rem; }
h3 { font-size: 1.75rem; }

p {
    margin-bottom: var(--spacing-sm);
    font-size: 1.125rem;
}

a {
    color: var(--color-text);
    text-decoration: none;
}

ul {
    list-style: none;
}

/* Utilities */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.section {
    padding: var(--spacing-xl) 0;
    border-bottom: var(--border-width) solid var(--color-border);
}

.grid {
    display: grid;
    gap: var(--spacing-md);
}

.grid-2 { grid-template-columns: 1fr 1fr; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-sm { gap: var(--spacing-sm); }

.text-center { text-align: center; }
.bg-pink { background-color: var(--color-accent-pink); }
.bg-yellow { background-color: var(--color-accent-yellow); }
.bg-green { background-color: var(--color-accent-green); }
.bg-black { background-color: var(--color-primary); color: white; }

/* Components */
.btn {
    display: inline-block;
    padding: 1rem 2rem;
    font-weight: 700;
    font-size: 1.125rem;
    border: var(--border-width) solid var(--color-border);
    background-color: var(--color-bg);
    color: var(--color-text);
    cursor: pointer;
    transition: all 0.1s ease;
    box-shadow: var(--shadow-hard);
}

.btn:hover {
    transform: translate(2px, 2px);
    box-shadow: var(--shadow-hover);
}

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

.btn-black {
    background-color: var(--color-primary);
    color: white;
}

.card {
    border: var(--border-width) solid var(--color-border);
    padding: var(--spacing-md);
    background-color: white;
    box-shadow: var(--shadow-hard);
    transition: transform 0.2s;
}

.card:hover {
    transform: translate(-2px, -2px);
    box-shadow: 7px 7px 0px 0px var(--color-border);
}

/* Navbar */
.navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: var(--color-bg);
    border-bottom: var(--border-width) solid var(--color-border);
    padding: 1rem 0;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-weight: 900;
    font-size: 1.5rem;
    border: 2px solid black;
    padding: 0.25rem 0.5rem;
    background: var(--color-accent-yellow);
    box-shadow: 3px 3px 0 0 black;
}

.nav-links {
    display: flex;
    gap: var(--spacing-md);
}

.nav-links a {
    font-weight: 600;
    position: relative;
}

.nav-links a:hover::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: black;
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
}

/* Footer */
.footer {
    background-color: var(--color-text);
    color: white;
    padding: var(--spacing-xl) 0;
}

.footer a {
    color: white;
    text-decoration: underline;
}

/* Responsive */
@media (max-width: 768px) {
    h1 { font-size: 2.5rem; }
    h2 { font-size: 2rem; }
    
    .grid-2, .grid-3 { grid-template-columns: 1fr; }
    
    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: white;
        flex-direction: column;
        padding: var(--spacing-md);
        border-bottom: var(--border-width) solid black;
    }
    
    .nav-links.active {
        display: flex;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .section { padding: var(--spacing-lg) 0; }
}