:root {
    --bg-color: #ffffff;
    --text-color: #333333;
    --primary-color: #ff6b6b;
    --secondary-color: #f8f9fa;
    --border-color: #e9ecef;
    --accent-color: #4dabf7;
}

[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --text-color: #f8f9fa;
    --primary-color: #ff8787;
    --secondary-color: #2d2d2d;
    --border-color: #404040;
}

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

body {
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

/* Header & Nav */
header {
    background-color: var(--bg-color);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar {
    max-width: 1000px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
}

/* Main Layout */
main {
    max-width: 800px;
    margin: 2rem auto;
    padding: 0 2rem;
}

section {
    margin-bottom: 4rem;
}

h1, h2 {
    margin-bottom: 1.5rem;
    text-align: center;
}

hr {
    border: 0;
    border-top: 1px solid var(--border-color);
    margin: 4rem 0;
}

/* Hero Section (Recommendation) */
.hero-section {
    text-align: center;
    padding: 4rem 0;
}

.input-container {
    display: flex;
    gap: 10px;
    justify-content: center;
    margin-top: 2rem;
}

input[type="number"] {
    padding: 12px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    width: 250px;
    font-size: 1rem;
    background-color: var(--secondary-color);
    color: var(--text-color);
}

button {
    padding: 12px 24px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: bold;
    transition: opacity 0.2s;
}

button:hover {
    opacity: 0.9;
}

/* Info Section (Cards) */
.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.info-card {
    background-color: var(--secondary-color);
    padding: 1.5rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.info-card h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

/* Form Styles */
.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: bold;
}

input[type="email"], textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--secondary-color);
    color: var(--text-color);
}

/* Footer */
footer {
    background-color: var(--secondary-color);
    padding: 3rem 2rem;
    border-top: 1px solid var(--border-color);
    margin-top: 4rem;
}

.footer-content {
    max-width: 1000px;
    margin: 0 auto;
    text-align: center;
}

.footer-links {
    list-style: none;
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-top: 1rem;
}

.footer-links a {
    color: var(--text-color);
    text-decoration: none;
    font-size: 0.9rem;
    opacity: 0.8;
}

/* Responsive */
@media (max-width: 600px) {
    .navbar {
        flex-direction: column;
        gap: 1rem;
    }
    .nav-links {
        gap: 1rem;
    }
    .input-container {
        flex-direction: column;
    }
    input[type="number"] {
        width: 100%;
    }
}