:root {
    --bg-color: #f4f7f9;
    --container-bg: #ffffff;
    --text-color: #2c3e50;
    --nav-bg: #ffffff;
    --footer-bg: #eef2f5;
    --primary-blue: #2980b9;
    --secondary-blue: #3498db;
    --accent-green: #27ae60;
    --accent-red: #e74c3c;
    --border-color: #dcdde1;
    --shadow: 0 4px 12px rgba(0,0,0,0.08);
}

body.dark-mode {
    --bg-color: #1a1c1e;
    --container-bg: #2d3436;
    --text-color: #f5f6fa;
    --nav-bg: #2d3436;
    --footer-bg: #202426;
    --primary-blue: #3498db;
    --secondary-blue: #5dade2;
    --border-color: #4b4b4b;
    --shadow: 0 4px 12px rgba(0,0,0,0.4);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe 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 {
    background-color: var(--nav-bg);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
}

.logo {
    font-size: 1.6rem;
    font-weight: 800;
    color: var(--primary-blue);
    letter-spacing: -1px;
}

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

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 600;
    font-size: 0.95rem;
}

.nav-links a:hover {
    color: var(--primary-blue);
}

.container {
    max-width: 1000px;
    margin: 3rem auto;
    padding: 0 1.5rem;
}

section {
    background: var(--container-bg);
    padding: 3rem;
    border-radius: 16px;
    box-shadow: var(--shadow);
    margin-bottom: 2.5rem;
}

.hero {
    text-align: center;
}

.hero h1 {
    font-size: 2.8rem;
    margin-bottom: 0.8rem;
    font-weight: 800;
}

.input-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-top: 2.5rem;
    text-align: left;
}

.input-group label {
    display: block;
    font-weight: 700;
    margin-bottom: 0.8rem;
    font-size: 1rem;
}

textarea {
    width: 100%;
    height: 300px;
    padding: 1rem;
    border: 1.5px solid var(--border-color);
    border-radius: 10px;
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: inherit;
    font-size: 0.9rem;
    resize: vertical;
    transition: border-color 0.2s;
}

textarea:focus {
    outline: none;
    border-color: var(--primary-blue);
}

.btn-primary {
    background-color: var(--primary-blue);
    color: white;
    padding: 1rem 2.5rem;
    font-size: 1.1rem;
    font-weight: 700;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    margin-top: 2rem;
    transition: transform 0.1s, background-color 0.2s;
}

.btn-primary:hover {
    background-color: var(--secondary-blue);
    transform: translateY(-2px);
}

.result-area {
    margin-top: 3.5rem;
    padding-top: 2rem;
    border-top: 2px dashed var(--border-color);
}

.score-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 2rem;
}

.score-circle {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    border: 8px solid var(--accent-green);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

.feedback-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    text-align: left;
}

.feedback-item {
    padding: 1.5rem;
    border-radius: 10px;
    background-color: var(--bg-color);
    border-left: 4px solid var(--primary-blue);
}

.feedback-item.warning { border-left-color: var(--accent-red); }
.feedback-item.success { border-left-color: var(--accent-green); }

.feedback-item h4 {
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.hidden { display: none; }

.info-section h2 {
    margin-bottom: 2rem;
    font-size: 1.8rem;
    position: relative;
    padding-bottom: 0.5rem;
}

.info-section h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 4px;
    background-color: var(--primary-blue);
}

.guide-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.contact-form form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    max-width: 600px;
    margin: 0 auto;
}

.btn-success {
    background-color: var(--accent-green);
    color: white;
    font-weight: 700;
}

footer {
    background-color: var(--footer-bg);
    padding: 4rem 2rem;
    text-align: center;
}

.footer-nav {
    margin-top: 1.5rem;
    display: flex;
    justify-content: center;
    gap: 2.5rem;
}

@media (max-width: 768px) {
    .input-grid {
        grid-template-columns: 1fr;
    }
    .navbar {
        flex-direction: column;
        gap: 1.5rem;
    }
    section {
        padding: 2rem 1.5rem;
    }
}