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

:root {
  --bg: #f0f4f8;
  --card-bg: #ffffff;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --accent: #10b981;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --border: #e2e8f0;
  --error: #ef4444;
  --shadow: 0 4px 24px rgba(0,0,0,0.08);
}

.dark {
  --bg: #0f172a;
  --card-bg: #1e293b;
  --primary: #3b82f6;
  --primary-hover: #60a5fa;
  --accent: #34d399;
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --border: #334155;
  --shadow: 0 4px 24px rgba(0,0,0,0.3);
}

body {
  font-family: 'DM Sans', sans-serif;
  background: var(--bg);
  color: var(--text-primary);
  min-height: 100vh;
  transition: background 0.3s ease, color 0.3s ease;
  line-height: 1.6;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 32px;
  flex-wrap: wrap;
  gap: 16px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo-icon {
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 700;
  font-size: 20px;
}

h1 {
  font-size: 28px;
  font-weight: 700;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.dark-toggle {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  border: 2px solid var(--border);
  background: var(--card-bg);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  transition: all 0.2s ease;
  box-shadow: var(--shadow);
}

.dark-toggle:hover {
  border-color: var(--primary);
  transform: scale(1.05);
}

.dashboard {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

@media (min-width: 768px) {
  .dashboard {
    grid-template-columns: 1fr 1fr;
  }
}

.card {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 24px;
  box-shadow: var(--shadow);
  transition: all 0.3s ease;
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
  padding-bottom: 16px;
  border-bottom: 2px solid var(--border);
}

.card-title {
  font-size: 18px;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
}

.card-title::before {
  content: '';
  width: 4px;
  height: 20px;
  background: var(--primary);
  border-radius: 2px;
}

.grade-row {
  display: grid;
  grid-template-columns: 1fr 80px 120px 40px;
  gap: 12px;
  margin-bottom: 12px;
  align-items: start;
  animation: slideIn 0.3s ease;
}

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

@media (max-width: 600px) {
  .grade-row {
    grid-template-columns: 1fr;
    background: var(--bg);
    padding: 16px;
    border-radius: 8px;
  }
}

.input-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.input-group label {
  font-size: 12px;
  font-weight: 500;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

input {
  padding: 12px 14px;
  border: 2px solid var(--border);
  border-radius: 8px;
  font-family: 'DM Sans', sans-serif;
  font-size: 15px;
  background: var(--bg);
  color: var(--text-primary);
  transition: all 0.2s ease;
}

input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

input.error {
  border-color: var(--error);
  box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.15);
}

input[type="number"] {
  font-family: 'JetBrains Mono', monospace;
}

.remove-btn {
  width: 40px;
  height: 42px;
  margin-top: 26px;
  border: 2px solid var(--border);
  border-radius: 8px;
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  justify-content: center;
}

.remove-btn:hover {
  border-color: var(--error);
  color: var(--error);
  background: rgba(239, 68, 68, 0.1);
}

.expense-input {
  margin-top: 20px;
  padding-top: 20px;
  border-top: 2px solid var(--border);
}

.expense-input .input-group input {
  font-family: 'JetBrains Mono', monospace;
  font-size: 18px;
  font-weight: 500;
}

.btn-add {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 20px;
  border: 2px dashed var(--border);
  border-radius: 8px;
  background: transparent;
  color: var(--text-secondary);
  font-family: 'DM Sans', sans-serif;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
  margin-top: 8px;
}

.btn-add:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: rgba(37, 99, 235, 0.05);
}

.btn-calculate {
  width: 100%;
  padding: 16px 24px;
  margin-top: 24px;
  background: linear-gradient(135deg, var(--primary), #1d4ed8);
  border: none;
  border-radius: 8px;
  color: white;
  font-family: 'DM Sans', sans-serif;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

.btn-calculate:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(37, 99, 235, 0.3);
}

.btn-calculate:active {
  transform: translateY(0);
}

.results-section {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.table-wrapper {
  overflow-x: auto;
  border-radius: 8px;
  border: 2px solid var(--border);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

thead {
  background: var(--bg);
}

th {
  padding: 14px 16px;
  text-align: left;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  font-size: 11px;
  letter-spacing: 0.5px;
  white-space: nowrap;
}

td {
  padding: 14px 16px;
  border-top: 1px solid var(--border);
  font-family: 'JetBrains Mono', monospace;
}

tbody tr:nth-child(even) {
  background: var(--bg);
}

tbody tr:hover {
  background: rgba(37, 99, 235, 0.05);
}

.total-row {
  background: linear-gradient(135deg, var(--primary), var(--accent)) !important;
  color: white;
  font-weight: 600;
}

.total-row td {
  border-top: none;
}

.summary-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

@media (max-width: 500px) {
  .summary-grid {
    grid-template-columns: 1fr;
  }
}

.summary-item {
  background: var(--bg);
  padding: 16px;
  border-radius: 8px;
  text-align: center;
}

.summary-item.highlight {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: white;
}

.summary-label {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 8px;
  opacity: 0.8;
}

.summary-value {
  font-family: 'JetBrains Mono', monospace;
  font-size: 24px;
  font-weight: 600;
}

.placeholder {
  text-align: center;
  padding: 40px;
  color: var(--text-secondary);
}

.placeholder-icon {
  font-size: 48px;
  margin-bottom: 16px;
  opacity: 0.5;
}

.error-msg {
  color: var(--error);
  font-size: 12px;
  margin-top: 4px;
  display: none;
}

.error-msg.visible {
  display: block;
}

footer {
  text-align: center;
  padding: 32px;
  color: var(--text-secondary);
  font-size: 13px;
}

.fade-out {
  animation: fadeOut 0.3s ease forwards;
}

@keyframes fadeOut {
  to {
    opacity: 0;
    transform: translateY(10px);
  }
}

#toastContainer {
  position: fixed;
  top: 24px;
  right: 24px;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-width: 380px;
}

.toast {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px 20px;
  background: var(--card-bg);
  border-radius: 10px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.15);
  border-left: 4px solid var(--error);
  transform: translateX(120%);
  transition: transform 0.3s ease, opacity 0.3s ease;
  animation: slideInToast 0.3s ease;
}

.toast-show {
  transform: translateX(0);
}

.toast-success {
  border-left-color: var(--accent);
}

.toast-error {
  border-left-color: var(--error);
}

.toast-icon {
  font-size: 18px;
  flex-shrink: 0;
}

.toast-message {
  flex: 1;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
  line-height: 1.4;
}

.toast-close {
  background: none;
  border: none;
  font-size: 20px;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 0;
  line-height: 1;
  opacity: 0.7;
  transition: opacity 0.2s;
}

.toast-close:hover {
  opacity: 1;
}

@keyframes slideInToast {
  from {
    opacity: 0;
    transform: translateX(100%);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

input.error {
  border-color: var(--error) !important;
  animation: shake 0.4s ease;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-5px); }
  75% { transform: translateX(5px); }
}