* { box-sizing: border-box; }

:root {
    --bg: #f4f6f8;
    --card-bg: #ffffff;
    --text: #1f2937;
    --muted: #6b7280;
    --primary: #1d4ed8;
    --primary-dark: #1e40af;
    --border: #d1d5db;
    --success-bg: #dcfce7;
    --success-text: #166534;
    --error-bg: #fee2e2;
    --error-text: #991b1b;
    --warning-bg: #fef9c3;
    --warning-text: #854d0e;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #111827;
        --card-bg: #1f2937;
        --text: #e5e7eb;
        --muted: #9ca3af;
        --primary: #3b82f6;
        --primary-dark: #60a5fa;
        --border: #374151;
        --success-bg: #14532d;
        --success-text: #bbf7d0;
        --error-bg: #7f1d1d;
        --error-text: #fecaca;
        --warning-bg: #713f12;
        --warning-text: #fef08a;
    }
}

body {
    margin: 0;
    font-family: "Tahoma", "Segoe UI", Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
}

.container {
    max-width: 780px;
    margin: 0 auto;
    padding: 24px 16px 64px;
}

h1 { font-size: 22px; margin-bottom: 4px; }
h2 { font-size: 18px; margin-top: 0; }
.hint { color: var(--muted); font-size: 14px; margin-bottom: 20px; }

.card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 20px;
    margin-bottom: 20px;
}

.hidden { display: none; }

input[type=text], input[type=password] {
    width: 100%;
    padding: 10px 12px;
    margin: 6px 0 14px;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 15px;
    background: var(--card-bg);
    color: var(--text);
}

label { font-weight: 600; font-size: 14px; }

button {
    background: var(--primary);
    color: #fff;
    border: none;
    padding: 10px 20px;
    border-radius: 6px;
    font-size: 15px;
    cursor: pointer;
}
button:hover { background: var(--primary-dark); }

.search-results {
    margin-top: 8px;
    max-height: 320px;
    overflow-y: auto;
}

.result-item {
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: 6px;
    margin-bottom: 6px;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    gap: 12px;
}
.result-item:hover { background: rgba(29, 78, 216, 0.08); }
.result-item .name { font-weight: 600; }
.result-item .meta { color: var(--muted); font-size: 13px; white-space: nowrap; }

.selected-student {
    background: rgba(29, 78, 216, 0.08);
    border-radius: 6px;
    padding: 10px 12px;
    margin-bottom: 16px;
    font-weight: 600;
}

.alert {
    padding: 12px 14px;
    border-radius: 8px;
    margin-bottom: 16px;
    font-size: 14px;
}
.alert-error { background: var(--error-bg); color: var(--error-text); }
.alert-success { background: var(--success-bg); color: var(--success-text); }
.alert-warning { background: var(--warning-bg); color: var(--warning-text); }

code {
    background: rgba(127,127,127,0.15);
    padding: 1px 6px;
    border-radius: 4px;
}

/* Top nav */
.topnav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: var(--card-bg);
    border-bottom: 1px solid var(--border);
    padding: 12px 20px;
    flex-wrap: wrap;
    gap: 10px;
}
.topnav .brand { font-weight: 700; font-size: 16px; }
.nav-links a {
    margin-inline-start: 16px;
    text-decoration: none;
    color: var(--text);
    font-size: 14px;
    padding: 6px 4px;
}
.nav-links a.active { color: var(--primary); font-weight: 700; border-bottom: 2px solid var(--primary); }
.nav-user { display: flex; align-items: center; gap: 12px; font-size: 14px; color: var(--muted); }
.logout-link { color: var(--error-text); text-decoration: none; }

/* Login page */
.login-page {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
}
.login-box {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 32px;
    width: 100%;
    max-width: 380px;
    text-align: center;
}
.login-box h1 { font-size: 18px; margin-bottom: 4px; }
.login-box h2 { font-size: 15px; color: var(--muted); font-weight: 400; margin-bottom: 20px; }
.login-box form { text-align: right; }
.login-box button { width: 100%; margin-top: 8px; padding: 12px; }