:root {
    --bg-color: #f7fafc;
    --header-bg: #1a202c;
    --accent-color: #38b2ac;
    --text-main: #2d3748;
    --text-muted: #718096;
    --card-bg: #ffffff;
    --border-color: #e2e8f0;
    --danger: #e53e3e;
    --success: #38a169;
}

body {
    font-family: 'Inter', -apple-system, system-ui, sans-serif;
    background: var(--bg-color);
    color: var(--text-main);
    margin: 0;
    padding: 0;
    line-height: 1.4;
}

/* Navigointipalkki */
.nav-bar {
    display: flex;
    justify-content: center;
    gap: 15px;
    background: var(--header-bg);
    padding: 12px;
    border-bottom: 2px solid var(--accent-color);
}

.nav-bar a {
    color: #a0aec0;
    text-decoration: none;
    font-weight: 700;
    font-size: 0.85rem;
    text-transform: uppercase;
    padding: 6px 16px;
    border-radius: 6px;
    transition: all 0.2s;
}

.nav-bar a:hover {
    color: #fff;
    background: rgba(255,255,255,0.05);
}

.nav-bar a.active {
    color: #fff;
    background: var(--accent-color);
}

/* Taulukon yleisrakenne */
.table-container {
    background: var(--card-bg);
    border-radius: 12px;
    border: 1px solid var(--border-color);
    overflow: hidden;
    margin: 0 20px 30px 20px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

table {
    width: 100%;
    border-collapse: collapse;
    table-layout: auto;
}

th {
    background: #f8fafc;
    padding: 10px 15px;
    text-align: left;
    font-size: 0.75rem;
    color: var(--header-bg);
    text-transform: uppercase;
    font-weight: 800;
    border-bottom: 2px solid var(--border-color);
}

td {
    padding: 8px 15px;
    border-bottom: 1px solid var(--border-color);
    font-size: 0.9rem;
}

tr:last-child td { border-bottom: none; }

/* Luokan otsikkopalkki */
.class-header {
    background: #edf2f7;
    padding: 12px 20px;
    font-weight: 800;
    border-bottom: 1px solid var(--border-color);
    color: var(--header-bg);
    text-transform: uppercase;
    font-size: 0.9rem;
}

.btn {
    padding: 8px 18px;
    border-radius: 6px;
    border: none;
    font-weight: 700;
    font-size: 0.85rem;
    cursor: pointer;
    transition: all 0.2s;
    text-transform: uppercase;
}

.btn-primary { background: var(--accent-color); color: white; }
.btn-save    { background: var(--header-bg); color: white; }
.btn-danger  { background: var(--danger); color: white; padding: 4px 8px; }

/* Login */
.login-body {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background: var(--bg-color);
}

.login-card {
    background: white;
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    width: 100%;
    max-width: 360px;
    text-align: center;
}

.login-card h2 { margin: 0 0 8px; color: var(--header-bg); }
.login-card p  { color: var(--text-muted); margin-bottom: 24px; }

.form-group { text-align: left; margin-bottom: 16px; }
.form-group label { display: block; font-weight: 700; font-size: 0.85rem; margin-bottom: 6px; }
.form-group input {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 1rem;
    box-sizing: border-box;
}
.form-group input:focus { border-color: var(--accent-color); outline: none; }

#errorMessage {
    display: none;
    color: var(--danger);
    font-size: 0.85rem;
    margin-top: 12px;
}

/* Copyright footer */
.copyright {
    text-align: center;
    padding: 12px;
    font-size: 0.75rem;
    color: #a0aec0;
    background: #1a202c;
    margin-top: 40px;
}
.copyright a { color: #a0aec0; text-decoration: underline; }
.copyright a:hover { color: #fff; }
@media (max-width: 768px) {
    th, td { padding: 8px 10px; font-size: 0.8rem; }
    .nav-bar { gap: 8px; }
    .nav-bar a { font-size: 0.75rem; padding: 5px 10px; }
    .table-container { margin: 0 10px 20px 10px; }
}