:root {
    --c-bg: #f5f7fb;
    --c-card: #ffffff;
    --c-sidebar: #ffffff;
    --c-border: #e4e7ee;
    --c-border-strong: #cfd4dd;
    --c-text: #0f172a;
    --c-text-muted: #64748b;
    --c-text-subtle: #94a3b8;
    --c-primary: #4f46e5;
    --c-primary-hover: #4338ca;
    --c-primary-soft: #eef2ff;
    --c-success: #059669;
    --c-warning: #d97706;
    --c-danger: #dc2626;
    --c-danger-soft: #fef2f2;
    --c-accent-bg: #f1f5f9;
    --shadow-sm: 0 1px 2px rgba(16, 24, 40, .05);
    --shadow-md: 0 4px 12px rgba(16, 24, 40, .06);
    --radius: 10px;
    --radius-sm: 6px;
    --sidebar-width: 260px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; height: 100%; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Inter", Roboto, Helvetica, Arial, sans-serif;
    font-size: 14px;
    color: var(--c-text);
    background: var(--c-bg);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}
a { color: var(--c-primary); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ===== App shell ===== */
.app {
    display: grid;
    grid-template-columns: var(--sidebar-width) 1fr;
    min-height: 100vh;
}

/* ===== Sidebar ===== */
.sidebar {
    background: var(--c-sidebar);
    border-right: 1px solid var(--c-border);
    display: flex;
    flex-direction: column;
    position: sticky;
    top: 0;
    height: 100vh;
    padding: 20px 14px;
}
.brand {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 4px 8px 20px;
}
.brand-mark { font-size: 24px; }
.brand-text { font-weight: 700; font-size: 16px; letter-spacing: -.01em; }

.compose-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    background: var(--c-primary);
    color: #fff;
    border-radius: 999px;
    padding: 12px 18px;
    font-weight: 600;
    margin-bottom: 20px;
    transition: background .15s, transform .15s;
    box-shadow: var(--shadow-sm);
}
.compose-btn:hover {
    background: var(--c-primary-hover);
    text-decoration: none;
    color: #fff;
}
.compose-icon { font-size: 16px; }

.nav { display: flex; flex-direction: column; gap: 2px; flex: 1; overflow-y: auto; }
.nav-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 9px 12px;
    border-radius: 999px;
    color: var(--c-text);
    font-weight: 500;
    transition: background .12s;
}
.nav-item:hover { background: var(--c-accent-bg); text-decoration: none; }
.nav-item.active { background: var(--c-primary-soft); color: var(--c-primary); font-weight: 600; }
.nav-icon { width: 20px; text-align: center; font-size: 14px; }
.nav-label { flex: 1; }
.nav-badge {
    background: var(--c-primary);
    color: #fff;
    font-size: 11px;
    font-weight: 700;
    padding: 2px 8px;
    border-radius: 999px;
}
.nav-divider {
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: .08em;
    color: var(--c-text-subtle);
    padding: 18px 12px 6px;
}

.sidebar-footer {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 8px 4px;
    border-top: 1px solid var(--c-border);
    margin-top: 10px;
}
.user-chip { display: flex; align-items: center; gap: 10px; flex: 1; min-width: 0; }
.avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: linear-gradient(135deg, #6366f1, #8b5cf6);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 13px;
    flex-shrink: 0;
}
.user-info { min-width: 0; }
.user-name { font-weight: 600; font-size: 13px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.user-email { font-size: 11px; color: var(--c-text-muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.logout-link {
    width: 32px;
    height: 32px;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--c-text-muted);
    font-size: 16px;
}
.logout-link:hover { background: var(--c-accent-bg); text-decoration: none; }

/* ===== Main content ===== */
.main {
    padding: 32px 40px;
    min-width: 0;
    max-width: 1280px;
}
.page-header {
    margin-bottom: 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    flex-wrap: wrap;
}
.page-header h1 {
    margin: 0;
    font-size: 22px;
    font-weight: 700;
    letter-spacing: -.01em;
}
.page-sub {
    color: var(--c-text-muted);
    font-size: 13px;
}

/* ===== Cards ===== */
.card {
    background: var(--c-card);
    border: 1px solid var(--c-border);
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: var(--shadow-sm);
    margin-bottom: 16px;
}
.card h3 { margin: 0 0 14px; font-size: 16px; font-weight: 600; }
.card h4 { font-size: 14px; font-weight: 600; }
.hint { color: var(--c-text-muted); font-size: 13px; margin: 0 0 12px; }

.settings-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}
@@media (max-width: 900px) {
    .settings-grid { grid-template-columns: 1fr; }
}

/* ===== Flash / Alert ===== */
.flash, .alert {
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    margin-bottom: 16px;
    font-size: 13px;
}
.flash {
    background: #ecfdf5;
    border: 1px solid #10b981;
    color: #065f46;
}
.alert-error {
    background: var(--c-danger-soft);
    border: 1px solid var(--c-danger);
    color: #991b1b;
}
.alert {
    background: #eff6ff;
    border: 1px solid #3b82f6;
    color: #1e40af;
}

/* ===== Forms ===== */
.form-group { margin-bottom: 14px; }
.form-group label {
    display: block;
    font-weight: 600;
    font-size: 13px;
    margin-bottom: 6px;
    color: var(--c-text);
}
.form-group small { color: var(--c-text-muted); font-size: 12px; display: block; margin-top: 4px; }
.form-group input[type="text"],
.form-group input[type="email"],
.form-group input[type="password"],
.form-group input[type="file"],
.form-group textarea,
.form-group select,
input[type="text"]:not([class]),
input[type="email"]:not([class]),
input[type="password"]:not([class]) {
    width: 100%;
    padding: 10px 12px;
    font: inherit;
    border: 1px solid var(--c-border-strong);
    border-radius: var(--radius-sm);
    background: #fff;
    transition: border-color .15s, box-shadow .15s;
}
.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--c-primary);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, .1);
}
.form-group textarea { min-height: 200px; resize: vertical; font-family: inherit; }
.form-group input:disabled { background: #f8fafc; color: var(--c-text-muted); }
.checkbox-row { display: flex; align-items: center; gap: 8px; font-weight: 500 !important; cursor: pointer; }
.checkbox-row input { margin: 0; }

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 9px 16px;
    background: #fff;
    color: var(--c-text);
    border: 1px solid var(--c-border-strong);
    border-radius: var(--radius-sm);
    font: inherit;
    font-weight: 600;
    cursor: pointer;
    transition: all .12s;
    text-decoration: none;
}
.btn:hover { background: #f8fafc; text-decoration: none; }
.btn-primary {
    background: var(--c-primary);
    color: #fff;
    border-color: var(--c-primary);
}
.btn-primary:hover { background: var(--c-primary-hover); border-color: var(--c-primary-hover); color: #fff; }
.btn-danger {
    background: var(--c-danger);
    color: #fff;
    border-color: var(--c-danger);
}
.btn-danger:hover { background: #b91c1c; color: #fff; }
.btn-ghost {
    background: transparent;
    border-color: transparent;
    color: var(--c-text-muted);
}
.btn-ghost:hover { background: var(--c-accent-bg); color: var(--c-text); }
.btn-sm { padding: 5px 10px; font-size: 12px; }

/* ===== Mail list ===== */
.mail-toolbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 16px;
    background: var(--c-card);
    border: 1px solid var(--c-border);
    border-radius: var(--radius) var(--radius) 0 0;
    border-bottom: none;
    font-size: 13px;
    color: var(--c-text-muted);
}
.mail-list {
    list-style: none;
    padding: 0;
    margin: 0;
    background: var(--c-card);
    border: 1px solid var(--c-border);
    border-radius: 0 0 var(--radius) var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}
.mail-list li {
    border-bottom: 1px solid var(--c-border);
}
.mail-list li:last-child { border-bottom: none; }
.mail-row {
    display: grid;
    grid-template-columns: 40px 220px 1fr 110px;
    gap: 12px;
    align-items: center;
    padding: 12px 16px;
    color: inherit;
    text-decoration: none;
    transition: background .1s;
}
.mail-row:hover { background: #f8fafc; text-decoration: none; }
.mail-row .sender-avatar {
    width: 32px; height: 32px; border-radius: 50%;
    background: linear-gradient(135deg, #e0e7ff, #c7d2fe);
    color: #4338ca;
    display: flex; align-items: center; justify-content: center;
    font-weight: 700; font-size: 12px;
}
.mail-row .from { font-weight: 500; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.mail-row .subject-line { display: flex; gap: 8px; overflow: hidden; min-width: 0; }
.mail-row .subject { font-weight: 500; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.mail-row .snippet { color: var(--c-text-muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.mail-row .date { color: var(--c-text-muted); font-size: 12px; text-align: right; white-space: nowrap; }
.mail-row.unread { background: #fdfdff; }
.mail-row.unread .from,
.mail-row.unread .subject { font-weight: 700; color: var(--c-text); }
.mail-row.unread::before {
    content: "";
    position: absolute;
    left: 0; top: 50%;
    transform: translateY(-50%);
    width: 3px; height: 24px;
    background: var(--c-primary);
    border-radius: 0 2px 2px 0;
}
.mail-list li { position: relative; }

.empty-state {
    background: var(--c-card);
    border: 1px solid var(--c-border);
    border-radius: var(--radius);
    padding: 60px 20px;
    text-align: center;
    color: var(--c-text-muted);
}
.empty-state .icon { font-size: 36px; margin-bottom: 12px; }

/* ===== Mail view ===== */
.mail-view .mail-view-header {
    border-bottom: 1px solid var(--c-border);
    padding-bottom: 18px;
    margin-bottom: 20px;
}
.mail-view .mail-view-header h2 { margin: 0 0 10px; font-size: 22px; font-weight: 600; }
.mail-view .meta { color: var(--c-text-muted); font-size: 13px; display: flex; flex-direction: column; gap: 4px; }
.mail-view .meta strong { color: var(--c-text); font-weight: 600; min-width: 60px; display: inline-block; }
.mail-view .mail-body {
    white-space: pre-wrap;
    line-height: 1.6;
    color: var(--c-text);
    font-size: 14px;
}

/* Attachments */
.attachments { margin-top: 24px; padding-top: 20px; border-top: 1px solid var(--c-border); }
.attachments h4 { margin: 0 0 10px; font-size: 13px; font-weight: 600; color: var(--c-text-muted); text-transform: uppercase; letter-spacing: .05em; }
.attachment-list { display: flex; flex-direction: column; gap: 8px; }
.attachment-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 14px;
    background: var(--c-accent-bg);
    border: 1px solid var(--c-border);
    border-radius: var(--radius-sm);
    color: inherit;
    transition: all .12s;
}
.attachment-item:hover { background: #e2e8f0; text-decoration: none; border-color: var(--c-border-strong); }
.attachment-item .att-name { font-weight: 600; font-size: 13px; }
.attachment-item .att-type { font-size: 11px; color: var(--c-text-muted); margin-top: 2px; }
.attachment-item .att-size { color: var(--c-primary); font-size: 12px; font-weight: 500; }

/* ===== Tables ===== */
.data-table {
    width: 100%;
    background: var(--c-card);
    border-collapse: collapse;
    border: 1px solid var(--c-border);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}
.data-table thead tr {
    background: #f8fafc;
    border-bottom: 1px solid var(--c-border);
}
.data-table th {
    text-align: left;
    padding: 12px 16px;
    font-weight: 600;
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: .04em;
    color: var(--c-text-muted);
}
.data-table td {
    padding: 12px 16px;
    border-bottom: 1px solid var(--c-border);
    font-size: 13px;
}
.data-table tr:last-child td { border-bottom: none; }
.data-table tr:hover td { background: #fafbfc; }

/* Status pills */
.pill {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 999px;
    font-size: 11px;
    font-weight: 600;
    letter-spacing: .02em;
}
.pill-success { background: #d1fae5; color: #065f46; }
.pill-warning { background: #fef3c7; color: #92400e; }
.pill-danger { background: #fee2e2; color: #991b1b; }
.pill-muted   { background: #e2e8f0; color: #475569; }
.pill-info    { background: #dbeafe; color: #1e40af; }

/* Stat cards */
.stat-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 14px;
    margin-bottom: 24px;
}
.stat-card {
    background: var(--c-card);
    border: 1px solid var(--c-border);
    border-radius: var(--radius);
    padding: 18px 22px;
    box-shadow: var(--shadow-sm);
}
.stat-card .stat-label {
    color: var(--c-text-muted);
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: .04em;
    margin-bottom: 8px;
    font-weight: 600;
}
.stat-card .stat-value { font-size: 28px; font-weight: 700; color: var(--c-text); }

/* ===== Utility ===== */
.mono { font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace; font-size: 12.5px; }
.text-muted { color: var(--c-text-muted); }
.text-mini { font-size: 12px; }
.mt-0 { margin-top: 0; }
.mt-2 { margin-top: 8px; }
.mt-4 { margin-top: 16px; }
.mb-0 { margin-bottom: 0; }
.inline-form { display: inline; }
.spacer { flex: 1; }
.flex-row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }

/* ===== Mobile ===== */
@@media (max-width: 760px) {
    .app { grid-template-columns: 1fr; }
    .sidebar { position: static; height: auto; padding: 12px; flex-direction: row; overflow-x: auto; gap: 8px; }
    .sidebar .brand { padding: 0 12px; }
    .compose-btn { margin: 0; }
    .nav { flex-direction: row; gap: 4px; }
    .sidebar-footer { border-top: none; margin: 0; padding: 0; }
    .main { padding: 16px; }
    .mail-row { grid-template-columns: 40px 1fr 80px; }
    .mail-row .subject-line { display: none; }
}