/* assets/style.css */
:root {
    --primary-color: #2563eb;    /* Xanh hiện đại */
    --secondary-color: #1e293b;  /* Xanh đen Slate */
    --bg-light: #f8fafc;
    --text-main: #334155;
    --white: #ffffff;
}

body {
    font-family: 'Inter', -apple-system, sans-serif;
    margin: 0;
    display: flex;
    flex-direction: column;
    height: 100vh;
    background-color: var(--bg-light);
    color: var(--text-main);
}

header {
    background: var(--secondary-color);
    color: var(--white);
    padding: 1.5rem;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

header h1 { margin: 0; font-size: 1.5rem; letter-spacing: 1px; }

.wrapper { display: flex; flex: 1; overflow: hidden; }

nav {
    width: 260px;
    background: var(--white);
    border-right: 1px solid #e2e8f0;
    padding: 1.5rem;
}

nav h3 { color: var(--secondary-color); font-size: 0.9rem; text-transform: uppercase; margin-bottom: 1rem; }

nav ul { list-style: none; padding: 0; }

nav li { margin-bottom: 0.5rem; }

nav a {
    display: block;
    padding: 0.75rem 1rem;
    color: var(--text-main);
    text-decoration: none;
    border-radius: 8px;
    transition: all 0.3s;
}

nav a:hover {
    background: #eff6ff;
    color: var(--primary-color);
    transform: translateX(5px);
}

main {
    flex: 1;
    padding: 2.5rem;
    overflow-y: auto;
    background: var(--bg-light);
}

.card {
    background: var(--white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

footer {
    background: var(--secondary-color);
    color: #94a3b8;
    text-align: center;
    padding: 1rem;
    font-size: 0.85rem;
}
.btn-primary { background: #2563eb; color: white; padding: 15px; border: none; border-radius: 8px; font-weight: bold; cursor: pointer; }
.score-select { border: 1px solid #cbd5e1; padding: 5px; border-radius: 4px; }