/* =============================================
   Öğrenci Yönetimi — App Styles
   Aesthetic: Clean editorial, geometric accents
   ============================================= */

:root {
  --bg: #0f1117;
  --bg-card: #161b27;
  --bg-card2: #1c2235;
  --border: #252d42;
  --border-light: #2e3a54;
  --text: #e8ecf4;
  --text-muted: #7a8aaa;
  --text-dim: #4a5678;
  --accent: #4f8ef7;
  --accent-dim: rgba(79,142,247,0.12);
  --green: #34c77b;
  --green-dim: rgba(52,199,123,0.12);
  --amber: #f5a623;
  --amber-dim: rgba(245,166,35,0.12);
  --red: #f25757;
  --red-dim: rgba(242,87,87,0.12);
  --purple: #a78bfa;
  --purple-dim: rgba(167,139,250,0.12);
  --sidebar-w: 220px;
  --radius: 10px;
  --font-display: 'Syne', sans-serif;
  --font-body: 'DM Sans', sans-serif;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { font-size: 15px; }

body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  line-height: 1.6;
}

/* ---- SIDEBAR ---- */
.sidebar {
  width: var(--sidebar-w);
  background: var(--bg-card);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0; left: 0; bottom: 0;
  z-index: 100;
}

.sidebar-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 24px 20px 20px;
  border-bottom: 1px solid var(--border);
}

.brand-icon {
  font-size: 24px;
  color: var(--accent);
  line-height: 1;
}

.brand-text {
  font-family: var(--font-display);
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.3;
}
.brand-text strong { color: var(--text); font-weight: 700; }

.nav-links {
  list-style: none;
  padding: 16px 12px;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 12px;
  border-radius: 7px;
  text-decoration: none;
  color: var(--text-muted);
  font-size: 13.5px;
  font-weight: 500;
  transition: all 0.15s;
}
.nav-link:hover { background: var(--bg-card2); color: var(--text); }
.nav-link.active { background: var(--accent-dim); color: var(--accent); }
.nav-icon { font-size: 14px; opacity: 0.8; }

.sidebar-footer {
  padding: 16px 20px;
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.user-name { font-size: 12px; color: var(--text-muted); }
.logout-link { font-size: 12px; color: var(--text-dim); text-decoration: none; }
.logout-link:hover { color: var(--red); }
.settings-link {
  font-size: 16px;
  color: var(--text-dim);
  text-decoration: none;
  line-height: 1;
  padding: 2px 4px;
  border-radius: 4px;
  transition: color 0.15s, background 0.15s;
}
.settings-link:hover { color: var(--accent); }
.settings-link.active { color: var(--accent); background: var(--accent-dim); }
.app-version {
  font-size: 11px;
  color: var(--text-dim);
  font-weight: 400;
  margin-left: 4px;
  letter-spacing: 0.3px;
}

/* ---- MAIN CONTENT ---- */
.main-content {
  margin-left: var(--sidebar-w);
  flex: 1;
  padding: 32px 36px;
  max-width: 1200px;
}

/* ---- PAGE HEADER ---- */
.page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 28px;
}

.page-title {
  font-family: var(--font-display);
  font-size: 26px;
  font-weight: 800;
  color: var(--text);
  letter-spacing: -0.5px;
}

/* ---- FLASH MESSAGES ---- */
.flash {
  padding: 12px 16px;
  border-radius: var(--radius);
  margin-bottom: 20px;
  font-size: 13.5px;
  font-weight: 500;
}
.flash-success { background: var(--green-dim); color: var(--green); border: 1px solid rgba(52,199,123,0.2); }
.flash-error { background: var(--red-dim); color: var(--red); border: 1px solid rgba(242,87,87,0.2); }

/* ---- STAT CARDS ---- */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  margin-bottom: 32px;
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  position: relative;
  overflow: hidden;
}
.stat-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
}
.stat-card--blue::before { background: var(--accent); }
.stat-card--green::before { background: var(--green); }
.stat-card--amber::before { background: var(--amber); }
.stat-card--purple::before { background: var(--purple); }

.stat-label { font-size: 12px; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 8px; }
.stat-value { font-family: var(--font-display); font-size: 24px; font-weight: 800; color: var(--text); }

/* ---- SECTION HEADER ---- */
.section-header { margin-bottom: 14px; }
.section-title { font-family: var(--font-display); font-size: 16px; font-weight: 700; color: var(--text); }

/* ---- TABLE CARD ---- */
.table-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 28px;
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13.5px;
}
.data-table th {
  background: var(--bg-card2);
  padding: 11px 16px;
  text-align: left;
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--text-muted);
  border-bottom: 1px solid var(--border);
}
.data-table td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  vertical-align: middle;
}
.data-table tr:last-child td { border-bottom: none; }
.data-table tr:hover td { background: rgba(255,255,255,0.02); }

.table-link { color: var(--accent); text-decoration: none; font-size: 13px; }
.table-link:hover { text-decoration: underline; }
.table-footer { font-size: 12px; color: var(--text-dim); margin-top: -20px; margin-bottom: 28px; padding: 0 4px; }

.empty { text-align: center; color: var(--text-dim); padding: 28px !important; }

/* ---- PROGRESS BAR ---- */
.progress-bar-wrap {
  background: var(--bg-card2);
  border-radius: 99px;
  height: 6px;
  position: relative;
  min-width: 80px;
}
.progress-bar {
  background: linear-gradient(90deg, var(--accent), var(--green));
  height: 100%;
  border-radius: 99px;
  transition: width 0.3s ease;
}
.progress-label {
  font-size: 11px;
  color: var(--text-muted);
  margin-left: 8px;
  vertical-align: middle;
  white-space: nowrap;
}

/* ---- TWO COLUMN LAYOUT ---- */
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }

/* ---- COHORT GRID ---- */
.cohort-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.cohort-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
}
.cohort-number {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 800;
  margin-bottom: 16px;
  color: var(--text);
}
.cohort-stats { display: flex; gap: 16px; margin-bottom: 4px; }
.cohort-stat { display: flex; flex-direction: column; gap: 3px; }
.cohort-stat-label { font-size: 11px; color: var(--text-dim); text-transform: uppercase; letter-spacing: 0.05em; }
.cohort-stat-value { font-size: 14px; font-weight: 600; }

/* ---- FILTER BAR ---- */
.filter-bar {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 18px;
  flex-wrap: wrap;
}
.filter-select, .filter-input {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 7px;
  padding: 8px 12px;
  font-size: 13.5px;
  font-family: var(--font-body);
}
.filter-select:focus, .filter-input:focus { outline: none; border-color: var(--accent); }
.filter-input { min-width: 200px; }

/* ---- BADGES ---- */
.badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 99px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.03em;
}
.badge-green { background: var(--green-dim); color: var(--green); }
.badge-purple { background: var(--purple-dim); color: var(--purple); }
.badge-gray { background: rgba(255,255,255,0.06); color: var(--text-muted); }

/* ---- BUTTONS ---- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 9px 18px;
  border-radius: 7px;
  font-family: var(--font-body);
  font-size: 13.5px;
  font-weight: 500;
  cursor: pointer;
  border: none;
  text-decoration: none;
  transition: all 0.15s;
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: #3d7de6; }
.btn-outline { background: transparent; border: 1px solid var(--border); color: var(--text-muted); }
.btn-outline:hover { border-color: var(--accent); color: var(--accent); }
.btn-ghost { background: transparent; color: var(--text-muted); }
.btn-ghost:hover { color: var(--text); }
.btn-danger { background: var(--red-dim); color: var(--red); border: 1px solid rgba(242,87,87,0.2); }
.btn-danger:hover { background: var(--red); color: #fff; }
.btn-sm { padding: 6px 12px; font-size: 12.5px; }
.btn-full { width: 100%; justify-content: center; }

.btn-icon-delete {
  background: none;
  border: none;
  color: var(--text-dim);
  cursor: pointer;
  font-size: 13px;
  padding: 3px 6px;
  border-radius: 4px;
}
.btn-icon-delete:hover { color: var(--red); background: var(--red-dim); }

/* ---- FORM CARD ---- */
.form-layout { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; align-items: start; }
.form-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
}
.form-section-title {
  font-family: var(--font-display);
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 22px;
  color: var(--text);
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}
.form-section-subtitle {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 14px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.form-group { display: flex; flex-direction: column; gap: 6px; margin-bottom: 16px; }
.form-group label { font-size: 12px; font-weight: 500; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.05em; }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.form-group--checks { justify-content: flex-end; padding-bottom: 4px; gap: 10px; }

input[type=text], input[type=email], input[type=number], input[type=date],
input[type=password], select, textarea {
  background: var(--bg-card2);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 7px;
  padding: 9px 12px;
  font-size: 13.5px;
  font-family: var(--font-body);
  width: 100%;
  transition: border-color 0.15s;
}
input:focus, select:focus, textarea:focus {
  outline: none;
  border-color: var(--accent);
  background: rgba(79,142,247,0.04);
}
textarea { resize: vertical; min-height: 80px; }
select option { background: var(--bg-card2); }

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-muted);
  cursor: pointer;
  text-transform: none;
  letter-spacing: 0;
}
.checkbox-label input[type=checkbox] { width: auto; accent-color: var(--accent); }

.form-actions { display: flex; gap: 10px; margin-top: 8px; align-items: center; }

/* ---- PAYMENT SUMMARY ---- */
.payment-summary {
  display: flex;
  gap: 0;
  background: var(--bg-card2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 20px;
  overflow: hidden;
}
.payment-summary-item {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 14px 18px;
  border-right: 1px solid var(--border);
}
.payment-summary-item:last-child { border-right: none; }
.payment-summary-item span { font-size: 11px; color: var(--text-dim); text-transform: uppercase; letter-spacing: 0.06em; }
.payment-summary-item strong { font-size: 17px; font-weight: 700; }

/* ---- COLOR UTILITIES ---- */
.text-green { color: var(--green); }
.text-amber { color: var(--amber); }
.text-red { color: var(--red); }
.text-blue { color: var(--accent); }

/* ---- LOGIN PAGE ---- */
.login-body {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  background: var(--bg);
}
.login-container { width: 100%; max-width: 400px; padding: 20px; }
.login-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 40px 36px;
}
.login-brand { text-align: center; margin-bottom: 32px; }
.brand-icon-lg { font-size: 36px; color: var(--accent); display: block; margin-bottom: 12px; }
.login-brand h1 { font-family: var(--font-display); font-size: 22px; font-weight: 800; margin-bottom: 6px; }
.login-brand p { font-size: 13px; color: var(--text-muted); }
.login-form .form-group { margin-bottom: 18px; }

/* ---- RESPONSIVE ---- */
@media (max-width: 1024px) {
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .two-col { grid-template-columns: 1fr; }
  .cohort-grid { grid-template-columns: repeat(2, 1fr); }
  .form-layout { grid-template-columns: 1fr; }
}
@media (max-width: 768px) {
  .sidebar { width: 60px; }
  .sidebar .brand-text, .sidebar .nav-link span:not(.nav-icon),
  .sidebar-footer .user-name, .sidebar-footer .logout-link, .sidebar-footer .settings-link { display: none; }
  .main-content { margin-left: 60px; padding: 20px; }
  .stats-grid { grid-template-columns: 1fr 1fr; }
  .form-row { grid-template-columns: 1fr; }
}