/* ═══════════════════════════════════════════
   RESET & BASE
═══════════════════════════════════════════ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:         #0b0f1a;
  --surface:    rgba(255,255,255,0.04);
  --surface-hv: rgba(255,255,255,0.08);
  --border:     rgba(255,255,255,0.08);
  --border-hv:  rgba(255,255,255,0.15);
  --text:       #e2e8f0;
  --text-muted: #94a3b8;
  --accent:     #7c3aed;
  --accent2:    #06b6d4;
  --accent-grd: linear-gradient(135deg, #7c3aed, #06b6d4);
  --green:      #4ade80;
  --yellow:     #fbbf24;
  --red:        #f87171;
  --radius:     16px;
  --radius-sm:  10px;
  --shadow:     0 8px 32px rgba(0,0,0,0.4);
  --font:       'Inter', system-ui, sans-serif;
}

html { scroll-behavior: smooth; }

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

/* ═══════════════════════════════════════════
   BACKGROUND ORBS
═══════════════════════════════════════════ */
.bg-orb {
  position: fixed;
  border-radius: 50%;
  filter: blur(100px);
  pointer-events: none;
  z-index: 0;
  animation: orb-float 12s ease-in-out infinite;
}
.orb-1 { width: 500px; height: 500px; background: rgba(124,58,237,0.18); top: -10%; left: -10%; animation-delay: 0s; }
.orb-2 { width: 400px; height: 400px; background: rgba(6,182,212,0.12); top: 40%; right: -8%; animation-delay: -4s; }
.orb-3 { width: 350px; height: 350px; background: rgba(124,58,237,0.1); bottom: 5%; left: 30%; animation-delay: -8s; }

@keyframes orb-float {
  0%, 100% { transform: translateY(0) scale(1); }
  50% { transform: translateY(-30px) scale(1.05); }
}

/* ═══════════════════════════════════════════
   CONTAINER
═══════════════════════════════════════════ */
.container {
  position: relative;
  z-index: 1;
  max-width: 860px;
  margin: 0 auto;
  padding: 2rem 1.5rem 4rem;
}

/* ═══════════════════════════════════════════
   HEADER
═══════════════════════════════════════════ */
.header {
  text-align: center;
  margin-bottom: 2.5rem;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -0.5px;
  margin-bottom: 0.5rem;
}
.logo strong { background: var(--accent-grd); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }

.logo-icon {
  width: 42px; height: 42px;
  background: var(--accent-grd);
  border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 4px 20px rgba(124,58,237,0.4);
}
.logo-icon svg { width: 22px; height: 22px; color: white; }

.tagline {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* ═══════════════════════════════════════════
   MODE TOGGLE
═══════════════════════════════════════════ */
.mode-toggle-wrapper {
  display: flex;
  justify-content: center;
  margin-bottom: 2rem;
}

.mode-toggle {
  display: inline-flex;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 50px;
  padding: 5px;
  gap: 4px;
  backdrop-filter: blur(12px);
}

.mode-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.55rem 1.4rem;
  border-radius: 50px;
  border: none;
  background: transparent;
  color: var(--text-muted);
  font-family: var(--font);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.25s ease;
}
.mode-btn svg { width: 16px; height: 16px; }
.mode-btn:hover { color: var(--text); background: var(--surface-hv); }
.mode-btn.active {
  background: var(--accent-grd);
  color: #fff;
  box-shadow: 0 4px 16px rgba(124,58,237,0.35);
}

/* ═══════════════════════════════════════════
   PANELS
═══════════════════════════════════════════ */
.panel {
  display: none;
  animation: fadeSlide 0.35s ease forwards;
}
.panel.active { display: block; }

@keyframes fadeSlide {
  from { opacity: 0; transform: translateY(14px); }
  to   { opacity: 1; transform: translateY(0); }
}

.panel-header {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem 2rem;
  margin-bottom: 1.25rem;
  backdrop-filter: blur(12px);
}
.panel-header h1 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0.35rem;
  background: var(--accent-grd);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.panel-header p { color: var(--text-muted); font-size: 0.92rem; }
.panel-header em { color: var(--text); font-style: normal; font-weight: 500; }

/* ═══════════════════════════════════════════
   OPTION ROW (toggle switch)
═══════════════════════════════════════════ */
.option-row {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.5rem;
  margin-bottom: 1.25rem;
  backdrop-filter: blur(12px);
}

.toggle-label {
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  gap: 1rem;
}
.toggle-text strong { display: block; font-size: 0.95rem; }
.toggle-text small { color: var(--text-muted); font-size: 0.8rem; }

.switch-wrap input { display: none; }
.switch {
  display: block;
  width: 50px; height: 26px;
  background: rgba(255,255,255,0.1);
  border-radius: 50px;
  position: relative;
  transition: background 0.25s;
  flex-shrink: 0;
}
.switch::after {
  content: '';
  position: absolute;
  width: 20px; height: 20px;
  background: #fff;
  border-radius: 50%;
  top: 3px; left: 3px;
  transition: transform 0.25s;
  box-shadow: 0 2px 6px rgba(0,0,0,0.3);
}
.switch-wrap input:checked ~ .switch { background: var(--accent); }
.switch-wrap input:checked ~ .switch::after { transform: translateX(24px); }

/* ═══════════════════════════════════════════
   CUMULATIVE INPUTS
═══════════════════════════════════════════ */
.cumulative-inputs {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin-bottom: 1.25rem;
  backdrop-filter: blur(12px);
  overflow: hidden;
  animation: slideDown 0.3s ease;
}
.cumulative-inputs.hidden { display: none; }

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-10px); }
  to   { opacity: 1; transform: translateY(0); }
}

.cumulative-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }

.form-group { display: flex; flex-direction: column; gap: 0.4rem; }
.form-group label { font-size: 0.82rem; color: var(--text-muted); font-weight: 500; letter-spacing: 0.3px; text-transform: uppercase; }
.form-group input {
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.6rem 0.9rem;
  color: var(--text);
  font-family: var(--font);
  font-size: 0.95rem;
  transition: border-color 0.2s, box-shadow 0.2s;
  outline: none;
}
.form-group input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(124,58,237,0.15);
}

/* ═══════════════════════════════════════════
   TABLE
═══════════════════════════════════════════ */
.table-wrapper {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow-x: auto;
  margin-bottom: 1rem;
  backdrop-filter: blur(12px);
}

.course-table { width: 100%; border-collapse: collapse; }
.course-table thead tr {
  background: rgba(255,255,255,0.04);
  border-bottom: 1px solid var(--border);
}
.course-table th {
  padding: 0.85rem 1rem;
  text-align: left;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-muted);
  font-weight: 600;
}

.course-table tbody tr {
  border-bottom: 1px solid var(--border);
  transition: background 0.2s;
}
.course-table tbody tr:last-child { border-bottom: none; }
.course-table tbody tr:hover { background: var(--surface-hv); }

.course-table td { padding: 0.75rem 1rem; }

/* Table inputs */
.course-table input[type="text"],
.course-table input[type="number"],
.course-table select {
  width: 100%;
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.5rem 0.75rem;
  color: var(--text);
  font-family: var(--font);
  font-size: 0.9rem;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}
.course-table select option { background: #1e2333; color: var(--text); }

.course-table input:focus,
.course-table select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(124,58,237,0.15);
}

.type-col { min-width: 130px; }
.type-col.hidden { display: none; }

/* Delete button */
.delete-btn {
  background: rgba(248,113,113,0.1);
  border: 1px solid rgba(248,113,113,0.2);
  color: var(--red);
  border-radius: 8px;
  width: 34px; height: 34px;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: all 0.2s;
}
.delete-btn:hover { background: rgba(248,113,113,0.25); transform: scale(1.08); }
.delete-btn svg { width: 15px; height: 15px; }

/* ═══════════════════════════════════════════
   ADD BUTTON
═══════════════════════════════════════════ */
.add-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--surface);
  border: 1px dashed var(--border-hv);
  color: var(--text-muted);
  border-radius: var(--radius-sm);
  padding: 0.65rem 1.25rem;
  font-family: var(--font);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.2s;
  margin-bottom: 1.5rem;
}
.add-btn svg { width: 16px; height: 16px; }
.add-btn:hover { color: var(--accent2); border-color: var(--accent2); background: rgba(6,182,212,0.06); }

/* ═══════════════════════════════════════════
   RESULT CARD
═══════════════════════════════════════════ */
.result-card {
  background: linear-gradient(135deg, rgba(124,58,237,0.12), rgba(6,182,212,0.08));
  border: 1px solid rgba(124,58,237,0.3);
  border-radius: var(--radius);
  padding: 1.75rem 2rem;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 2rem;
  flex-wrap: wrap;
  backdrop-filter: blur(12px);
  position: relative;
  overflow: hidden;
}
.result-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--accent-grd);
  opacity: 0.03;
  pointer-events: none;
}

.result-inner { text-align: center; min-width: 110px; }
.result-score {
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1;
  background: var(--accent-grd);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  transition: all 0.4s ease;
}
.result-label { color: var(--text-muted); font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.5px; margin-top: 0.3rem; }

.result-details {
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem;
  flex: 1;
}
.result-detail-item { display: flex; flex-direction: column; gap: 0.2rem; }
.rd-label { font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.5px; color: var(--text-muted); }
.rd-value { font-size: 1rem; font-weight: 600; color: var(--text); }

/* ═══════════════════════════════════════════
   CALCULATE BUTTON
═══════════════════════════════════════════ */
.calc-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  width: 100%;
  padding: 0.95rem;
  background: var(--accent-grd);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  font-family: var(--font);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.25s ease;
  box-shadow: 0 4px 24px rgba(124,58,237,0.35);
  position: relative;
  overflow: hidden;
}
.calc-btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255,255,255,0);
  transition: background 0.2s;
}
.calc-btn:hover { transform: translateY(-2px); box-shadow: 0 8px 32px rgba(124,58,237,0.5); }
.calc-btn:hover::after { background: rgba(255,255,255,0.07); }
.calc-btn:active { transform: translateY(0); }
.calc-btn svg { width: 18px; height: 18px; }

/* ═══════════════════════════════════════════
   GRADE REFERENCE
═══════════════════════════════════════════ */
.grade-reference {
  margin-top: 3rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem 2rem;
  backdrop-filter: blur(12px);
}
.grade-reference h2 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 1.25rem;
  color: var(--text);
}

.grade-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
  gap: 0.75rem;
}

.grade-card {
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.85rem 0.5rem;
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  transition: border-color 0.2s, transform 0.2s;
}
.grade-card:hover { border-color: var(--border-hv); transform: translateY(-2px); }
.grade-letter { font-size: 1.3rem; font-weight: 700; }
.grade-points { font-size: 0.85rem; font-weight: 600; color: var(--text); }
.grade-range { font-size: 0.7rem; color: var(--text-muted); }

/* ═══════════════════════════════════════════
   FOOTER
═══════════════════════════════════════════ */
.footer {
  text-align: center;
  margin-top: 3rem;
  color: var(--text-muted);
  font-size: 0.82rem;
}

/* ═══════════════════════════════════════════
   TOAST NOTIFICATION
═══════════════════════════════════════════ */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: rgba(30,35,51,0.95);
  border: 1px solid var(--border-hv);
  color: var(--text);
  padding: 0.75rem 1.5rem;
  border-radius: 50px;
  font-size: 0.9rem;
  font-weight: 500;
  backdrop-filter: blur(20px);
  z-index: 1000;
  opacity: 0;
  transition: all 0.3s ease;
  pointer-events: none;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
.toast.error { border-color: rgba(248,113,113,0.4); color: var(--red); }
.toast.success { border-color: rgba(74,222,128,0.4); color: var(--green); }

/* ═══════════════════════════════════════════
   UTILITY
═══════════════════════════════════════════ */
.hidden { display: none !important; }

/* ═══════════════════════════════════════════
   RESPONSIVE
═══════════════════════════════════════════ */
@media (max-width: 600px) {
  .container { padding: 1.25rem 1rem 3rem; }
  .result-card { flex-direction: column; gap: 1.25rem; }
  .result-inner { min-width: unset; }
  .cumulative-grid { grid-template-columns: 1fr; }
  .grade-grid { grid-template-columns: repeat(3, 1fr); }
  .panel-header { padding: 1.25rem 1.25rem; }
  .mode-btn { padding: 0.55rem 1rem; font-size: 0.82rem; }
  .result-score { font-size: 2.8rem; }
}