:root {
    --bg-color-light: #f4f7fc; --text-color-light: #1e293b; --card-bg-light: rgba(255, 255, 255, 0.7);
    --border-color-light: rgba(203, 213, 225, 0.9); --subtle-bg-light: #e2e8f0; --shadow-light: 0 8px 32px 0 rgba(31, 38, 135, 0.15);
    --bg-color-dark: #0f172a; --text-color-dark: #e2e8f0; --card-bg-dark: rgba(30, 41, 59, 0.6);
    --border-color-dark: rgba(51, 65, 85, 0.8); --subtle-bg-dark: #1e293b; --shadow-dark: 0 8px 32px 0 rgba(0, 0, 0, 0.2);
    --accent-color: #3b82f6; --accent-color-hover: #2563eb;
    --font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    --border-radius-lg: 1.5rem; --border-radius-md: 0.75rem; --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}
[data-theme="light"] { --bg-color: var(--bg-color-light); --text-color: var(--text-color-light); --card-bg: var(--card-bg-light); --border-color: var(--border-color-light); --subtle-bg: var(--subtle-bg-light); --shadow: var(--shadow-light); }
[data-theme="dark"] { --bg-color: var(--bg-color-dark); --text-color: var(--text-color-dark); --card-bg: var(--card-bg-dark); --border-color: var(--border-color-dark); --subtle-bg: var(--subtle-bg-dark); --shadow: var(--shadow-dark); }
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body { font-family: var(--font-family); background-color: var(--bg-color); color: var(--text-color); line-height: 1.6; transition: var(--transition); overflow-x: hidden; }
.container { max-width: 960px; margin: 0 auto; padding: 2rem 1.5rem; }
.header { padding: 1rem 0; position: sticky; top: 0; z-index: 100; background: var(--card-bg); backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px); border-bottom: 1px solid var(--border-color); }
.header .container { display: flex; justify-content: space-between; align-items: center; padding: 0 1.5rem; max-width: 1200px; }
.logo { font-weight: 700; font-size: 1.5rem; color: var(--text-color); text-decoration: none; }
.nav { display: flex; align-items: center; gap: 1rem; }
.nav a { color: var(--text-color); text-decoration: none; font-weight: 600; position: relative; padding: 0.5rem; }
.nav a::after { content: ''; position: absolute; width: 0; height: 2px; bottom: 0; left: 50%; transform: translateX(-50%); background-color: var(--accent-color); transition: var(--transition); }
.nav a:hover::after, .nav a.active::after { width: 80%; }
.nav a:hover, .nav a.active { color: var(--accent-color); }
.theme-toggle { background: transparent; border: none; cursor: pointer; color: var(--text-color); padding: 0.5rem; border-radius: 50%; }
[data-theme="light"] .moon-icon { display: none; } [data-theme="dark"] .sun-icon { display: none; }
.card { padding: 2.5rem; border-radius: var(--border-radius-lg); box-shadow: var(--shadow); text-align: center; background: var(--card-bg); border: 1px solid var(--border-color); }
h1 { font-size: 2.8rem; margin-bottom: 0.5rem; line-height: 1.2; }
.card > p { font-size: 1.1rem; margin-bottom: 1.5rem; max-width: 600px; margin-left: auto; margin-right: auto; opacity: 0.8; }
.gradient-preview { width: 100%; height: 320px; border-radius: var(--border-radius-md); margin-bottom: 2rem; transition: background 0.5s ease; border: 1px solid var(--border-color); }
.color-inputs { display: flex; justify-content: center; align-items: center; gap: 1rem; flex-wrap: wrap; margin-bottom: 2rem; }
.color-input { -webkit-appearance: none; -moz-appearance: none; appearance: none; width: 60px; height: 60px; background-color: transparent; border: none; cursor: pointer; }
.color-input::-webkit-color-swatch { border-radius: 50%; border: 4px solid var(--bg-color); box-shadow: 0 0 15px rgba(0,0,0,0.1); transition: transform 0.2s; }
.color-input:hover::-webkit-color-swatch { transform: scale(1.1); }
.output { display: flex; gap: 1rem; }
#css-code { width: 100%; padding: 1rem; border-radius: var(--border-radius-md); border: 1px solid var(--border-color); background-color: var(--subtle-bg); color: var(--text-color); font-family: 'Courier New', Courier, monospace; resize: none; font-size: 0.9rem; }
.modern-button { padding: 0 1.5rem; height: 50px; border: 1px solid var(--border-color); border-radius: var(--border-radius-md); font-weight: 600; cursor: pointer; transition: var(--transition); background-color: var(--subtle-bg); color: var(--text-color); white-space: nowrap; }
.modern-button:hover { transform: translateY(-2px); box-shadow: 0 4px 12px rgba(0,0,0,0.1); }
.modern-button.primary { background-color: var(--accent-color); color: white; border: none; }
.modern-button.primary:hover { background-color: var(--accent-color-hover); }
.download-section { margin-top: 3rem; padding-top: 2rem; border-top: 1px solid var(--border-color); }
.download-controls { display: flex; justify-content: center; align-items: center; gap: 1rem; flex-wrap: wrap; }
.dropdown { height: 50px; padding: 0 1rem; border-radius: var(--border-radius-md); border: 1px solid var(--border-color); background-color: var(--bg-color); color: var(--text-color); }
.content-section { text-align: left; max-width: 800px; margin: 4rem auto 0 auto; padding-top: 2rem; border-top: 1px solid var(--border-color); }
.content-section h2 { font-size: 2rem; margin-bottom: 1.5rem; text-align: center; }
.content-section h3 { font-size: 1.5rem; margin-bottom: 1rem; margin-top: 2rem; }
.content-section ul { margin-left: 1.5rem; margin-bottom: 1rem; }
.content-section code { background-color: var(--subtle-bg); padding: 0.2rem 0.4rem; border-radius: 0.25rem; font-family: 'Courier New', Courier, monospace; }
.faq-item { border-bottom: 1px solid var(--border-color); }
.faq-question { display: flex; justify-content: space-between; align-items: center; padding: 1.5rem 0; cursor: pointer; font-weight: 600; font-size: 1.2rem; }
.faq-question:hover { color: var(--accent-color); }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height 0.4s ease-out; }
.faq-answer p { padding-bottom: 1.5rem; }
.faq-item.active .faq-answer { max-height: 300px; }
.faq-toggle { font-size: 2rem; transition: transform 0.3s; }
.faq-item.active .faq-toggle { transform: rotate(45deg); }
.footer { text-align: center; padding: 3rem 1rem; margin-top: 4rem; border-top: 1px solid var(--border-color); }
.footer .footer-nav { margin-bottom: 1.5rem; display: flex; justify-content: center; flex-wrap: wrap; gap: 1.5rem; }
.footer-nav a { color: var(--text-color); text-decoration: none; font-weight: 500; opacity: 0.8; }
.footer-nav a:hover { opacity: 1; color: var(--accent-color); }
.footer p { opacity: 0.7; }

/* Burger menu icon */
.menu-toggle {
    display: none; /* Hidden by default on larger screens */
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    z-index: 110; /* Above header */
}
.menu-toggle .icon-bar {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--text-color);
    margin: 5px 0;
    transition: var(--transition);
}

/* Mobile menu container */
.mobile-nav-overlay {
    display: none; /* Hidden by default */
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7); /* Overlay background */
    z-index: 105;
    opacity: 0;
    transition: opacity 0.3s ease-in-out;
}

.mobile-nav {
    position: fixed;
    top: 0;
    right: -280px; /* Off-screen by default */
    width: 250px;
    height: 100%;
    background: var(--card-bg);
    border-left: 1px solid var(--border-color);
    box-shadow: -4px 0 12px rgba(0,0,0,0.1);
    padding-top: 4rem; /* Space for header */
    display: flex;
    flex-direction: column;
    gap: 1rem;
    transition: right 0.3s ease-in-out;
    z-index: 106;
}
.mobile-nav a {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 600;
    padding: 0.75rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    transition: var(--transition);
}
.mobile-nav a:hover {
    color: var(--accent-color);
    background-color: var(--subtle-bg);
}

/* State when menu is open */
body.menu-open .mobile-nav-overlay {
    display: block;
    opacity: 1;
}
body.menu-open .mobile-nav {
    right: 0; /* Slide in */
}
body.menu-open .menu-toggle .icon-bar:nth-child(1) {
    transform: translateY(8px) rotate(45deg);
}
body.menu-open .menu-toggle .icon-bar:nth-child(2) {
    opacity: 0;
}
body.menu-open .menu-toggle .icon-bar:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
}


/* Media queries for mobile */
@media (max-width: 768px) {
    .header .container {
        flex-direction: row; /* Keep logo and toggle on one line */
        justify-content: space-between;
        padding: 0.5rem 1.5rem;
    }
    .nav {
        display: none; /* Hide regular nav on small screens */
    }
    .menu-toggle {
        display: block; /* Show burger icon */
    }
    .theme-toggle {
        margin-left: 1rem; /* Space between burger and theme toggle */
    }
}

/* Typographic Scale Calculator Styles */
.typographic-scale-controls {
    display: flex;
    justify-content: center;
    align-items: stretch;
    gap: 1.5rem;
    flex-wrap: wrap;
    margin-top: 2.5rem;
    margin-bottom: 3rem;
    padding: 1.5rem;
    background-color: var(--subtle-bg);
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--border-color);
}

.control-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.75rem;
    flex: 1;
    min-width: 160px;
}

.control-group label {
    font-weight: 600;
    font-size: 0.9rem;
    opacity: 0.9;
}

.control-group input[type="number"],
.control-group select {
    width: 100%;
    height: 50px;
    padding: 0 1rem;
    border-radius: var(--border-radius-md);
    border: 1px solid var(--border-color);
    background-color: var(--bg-color);
    color: var(--text-color);
    text-align: center;
    font-size: 1.1rem;
    font-weight: 500;
    transition: var(--transition);
}

.control-group input[type="number"]:focus,
.control-group select:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.3);
}

.typographic-scale-preview {
    width: 100%;
    margin-top: 3rem;
    border-top: 1px solid var(--border-color);
    padding-top: 3rem;
}

.scale-item {
    padding: 1.75rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: grid;
    grid-template-columns: 1fr auto auto;
    gap: 1.5rem;
    align-items: baseline;
    transition: background-color 0.2s ease-in-out;
    border-radius: var(--border-radius-md);
}

.scale-item:first-child {
    border-top: 1px solid var(--border-color);
}

.scale-item:hover {
    background-color: var(--subtle-bg);
    transform: scale(1.02);
    box-shadow: var(--shadow);
    z-index: 1;
    position: relative;
}

.scale-item span {
    font-family: 'Inter', sans-serif;
    font-size: 1em; /* The font-size is set on the parent */
    line-height: 1.4;
}

.scale-item .size-details {
    font-family: 'Courier New', Courier, monospace;
    opacity: 0.7;
    font-size: 0.85rem;
    text-align: right;
}

.scale-item .size-px {
    font-weight: 700;
    opacity: 1;
    color: var(--accent-color);
    font-size: 1em;
}

.output-code-section {
    margin-top: 4rem;
    text-align: center;
}

.output-code-section h2 {
    margin-bottom: 1.5rem;
    font-size: 1.8rem;
}