/* Root variables for theme */
:root {
    --primary-color: #000000;
    --secondary-color: #ffffff;
    --accent-color: #cccccc;
    --text-color: #333333;
    --background-color: #f0f0f0;
    --border-color: #eeeeee;
    --spacing-unit: 10px;
    --font-family-primary: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    --font-family-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
}

/* Basic Reset & Body Styling */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    font-family: var(--font-family-primary);
    color: var(--text-color);
    background-color: var(--background-color);
    line-height: 1.6;
    height: 100%;
}

body {
    display: flex;
    flex-direction: column;
}

main {
    flex: 1;
    padding: var(--spacing-unit);
    max-width: 960px;
    margin: 0 auto;
    width: 100%;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-unit);
}

h1 { font-size: 2em; }
h2 { font-size: 1.5em; }
h3 { font-size: 1.2em; }

/* Links */
a {
    color: var(--primary-color);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

/* Buttons */
button, .button {
    background-color: var(--primary-color);
    color: var(--secondary-color);
    border: 1px solid var(--primary-color);
    padding: calc(var(--spacing-unit) * 1.5) var(--spacing-unit);
    cursor: pointer;
    font-size: 1em;
    text-transform: uppercase;
    letter-spacing: 1px;
    transition: all 0.3s ease;
    min-height: 48px; /* Focused interaction */
    display: inline-block;
    text-align: center;
}

button:hover, .button:hover {
    background-color: var(--secondary-color);
    color: var(--primary-color);
}

/* Forms */
input[type="text"],
input[type="email"],
input[type="password"],
input[type="number"],
textarea {
    width: 100%;
    padding: var(--spacing-unit);
    margin-bottom: var(--spacing-unit);
    border: 1px solid var(--accent-color);
    background-color: var(--secondary-color);
    color: var(--text-color);
    min-height: 48px; /* Focused interaction */
    font-size: 1em;
}

input[type="submit"] {
    width: 100%;
}

/* Header & Navigation */
header {
    background-color: var(--primary-color);
    color: var(--secondary-color);
    padding: var(--spacing-unit);
    border-bottom: 2px solid var(--accent-color);
}

header nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    max-width: 960px;
    margin: 0 auto;
}

header nav a {
    color: var(--secondary-color);
    padding: var(--spacing-unit);
    text-decoration: none;
    text-transform: uppercase;
    font-weight: bold;
}

header nav a:hover {
    background-color: var(--accent-color);
    color: var(--primary-color);
    text-decoration: none;
}

.lang-switcher {
    margin-left: var(--spacing-unit);
}

.lang-switcher a {
    padding: 5px;
    font-size: 0.9em;
}

/* Footer */
footer {
    background-color: var(--primary-color);
    color: var(--secondary-color);
    text-align: center;
    padding: var(--spacing-unit);
    margin-top: auto;
}

/* Mobile-First Adjustments (default styles are mobile-first) */
/* Desktop / Larger screens */
@media (min-width: 768px) {
    header nav {
        justify-content: flex-start;
    }

    header nav a {
        margin-right: var(--spacing-unit);
    }
}

/* Sticky Footer (for checkout button in mobile, general purpose here) */
.sticky-footer-btn {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    background-color: var(--primary-color);
    padding: var(--spacing-unit);
    text-align: center;
    box-shadow: 0 -2px 10px rgba(0,0,0,0.1);
    z-index: 1000;
}

.sticky-footer-btn button {
    width: calc(100% - 2 * var(--spacing-unit)); /* Account for padding */
    max-width: 400px; /* Optional: limit width on larger screens */
}