:root {
    --bg: #f5f7fb;
    --surface: #ffffff;
    --surface-soft: #f8fafc;
    --text: #101828;
    --muted: #667085;
    --border: #e4e7ec;
    --primary: #d10d12;
    --primary-hover: #b50b10;
    --secondary: #eef2f6;
    --secondary-text: #243447;
    --success: #027a48;
    --warning: #b54708;
    --danger: #b42318;
    --shadow: 0 10px 30px rgba(16, 24, 40, 0.06);
}

html[data-theme="dark"] {
    --bg: #0f1720;
    --surface: #17212b;
    --surface-soft: #1d2939;
    --text: #f2f4f7;
    --muted: #98a2b3;
    --border: #344054;
    --primary: #ff4d57;
    --primary-hover: #ff6670;
    --secondary: #243447;
    --secondary-text: #f2f4f7;
    --success: #32d583;
    --warning: #fdb022;
    --danger: #f97066;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: Arial, sans-serif;
    line-height: 1.5;
}

a {
    color: var(--primary);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

.container {
    width: min(1200px, calc(100% - 32px));
    margin: 0 auto;
}

.site-header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-inner {
    display: flex;
    justify-content: space-between;
    gap: 20px;
    align-items: center;
    min-height: 78px;
    padding: 12px 0;
}

.brand {
    display: flex;
    align-items: center;
    gap: 14px;
    color: var(--text);
    text-decoration: none;
}

.brand:hover {
    text-decoration: none;
}

.brand-logo {
    width: 54px;
    height: 54px;
    object-fit: contain;
    border-radius: 8px;
    background: #fff;
    padding: 2px;
}

.brand-title {
    display: block;
    font-size: 22px;
    font-weight: 700;
    color: var(--text);
}

.brand-subtitle {
    display: block;
    font-size: 13px;
    color: var(--muted);
}

.header-actions {
    display: flex;
    gap: 10px;
    align-items: center;
    flex-wrap: wrap;
}

.main-content {
    padding: 28px 0 40px;
}

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 18px;
    box-shadow: var(--shadow);
    padding: 24px;
}

.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 16px;
}

.dashboard-tile {
    background: var(--surface-soft);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 18px;
    display: flex;
    flex-direction: column;
    min-height: 180px;
}

.dashboard-tile h3 {
    margin-top: 0;
    margin-bottom: 10px;
}

.dashboard-tile p {
    margin-top: 0;
}

.tile-actions {
    margin-top: auto;
    padding-top: 16px;
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    min-height: 40px;
    padding: 10px 16px;
    border-radius: 10px;
    border: 1px solid transparent;
    background: var(--primary);
    color: #fff;
    text-decoration: none;
    font-weight: 600;
    cursor: pointer;
    transition: 0.2s ease;
}

.btn:hover {
    background: var(--primary-hover);
    text-decoration: none;
}

.btn-secondary {
    background: var(--secondary);
    color: var(--secondary-text);
    border-color: var(--border);
}

.btn-secondary:hover {
    filter: brightness(0.98);
}

.btn-danger {
    background: var(--danger);
}

.btn-muted {
    background: #98a2b3;
    cursor: default;
}

.muted {
    color: var(--muted);
}

.form-group {
    margin-bottom: 16px;
}

input[type="text"],
input[type="password"],
input[type="file"],
input[type="date"],
input[type="datetime-local"],
input[type="number"],
select,
textarea {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: 10px;
    background: var(--surface);
    color: var(--text);
    font-size: 15px;
}

textarea {
    resize: vertical;
}

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

th,
td {
    border-bottom: 1px solid var(--border);
    padding: 10px;
    vertical-align: top;
}

th {
    text-align: left;
    background: var(--surface);
}

.subcard {
    padding: 12px;
    border-radius: 12px;
    background: var(--surface-soft);
    border: 1px solid var(--border);
}

.alert {
    border-radius: 12px;
    padding: 12px 14px;
    margin-bottom: 16px;
    border: 1px solid var(--border);
}

.alert-success {
    background: rgba(2, 122, 72, 0.12);
    color: var(--success);
    border-color: rgba(2, 122, 72, 0.25);
}

.alert-warning {
    background: rgba(181, 71, 8, 0.12);
    color: var(--warning);
    border-color: rgba(181, 71, 8, 0.25);
}

.alert-error {
    background: rgba(180, 35, 24, 0.12);
    color: var(--danger);
    border-color: rgba(180, 35, 24, 0.25);
}

.status-success {
    color: var(--success);
    font-weight: 600;
}

.status-danger {
    color: var(--danger);
    font-weight: 600;
}

.status-warning {
    color: var(--warning);
    font-weight: 600;
}

details {
    border: 1px solid var(--border);
    border-radius: 10px;
    background: var(--surface-soft);
    padding: 10px 12px;
}

summary {
    cursor: pointer;
    font-weight: 600;
}

.student-summary-card {
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 14px;
    background: var(--surface);
}

.student-summary-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 10px;
    margin-top: 10px;
}

.page-actions {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    margin-top: 16px;
}

@media (max-width: 768px) {
    .header-inner {
        flex-direction: column;
        align-items: flex-start;
    }

    .brand-title {
        font-size: 18px;
    }

    .main-content {
        padding-top: 20px;
    }

    .card {
        padding: 18px;
    }
}