/* 
 * Simple Expense Splitter - CSS
 * Version: 1.0.1
 * Last Updated: 2024
 */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600&display=swap');

/* ===== CSS VARIABLES ===== */
:root {
  --primary: #6366f1;
  --primary-light: #8b5cf6;
  --primary-dark: #4f46e5;
  --accent: #f59e0b;
  --accent-light: #fbbf24;
  --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --card-glass: rgba(255,255,255,0.4);
  --card-border: rgba(255,255,255,0.7);
  --border: #e2e8f0;
  --text: #1e293b;
  --muted: #374151;
  --danger: #ef4444;
  --success: #10b981;
  --warning: #f59e0b;
  --shadow: 0 24px 48px rgba(0,0,0,0.18);
  --shadow-light: 0 6px 18px rgba(99,102,241,0.18);
  --shadow-medium: 0 12px 32px rgba(99,102,241,0.25);
  --shadow-heavy: 0 28px 56px rgba(0,0,0,0.22);
  --border-radius: 1rem;
  --border-radius-small: 0.75rem;
  --border-radius-large: 1.25rem;
  --transition: 0.3s;
  --transition-slow: 0.5s;
}

/* ===== BASE STYLES ===== */
html, body {
  font-family: 'Inter', sans-serif;
  background: var(--bg-gradient);
  margin: 0;
  padding: 0;
  color: var(--text);
  min-height: 100vh;
  width: 100vw;
  box-sizing: border-box;
  transition: background 0.6s cubic-bezier(.4,0,.2,1);
  overflow-x: hidden;
}

/* ===== LAYOUT ===== */
#app {
  width: 92vw;
  min-width: 0;
  max-width: 1200px;
  margin: 1.5rem auto;
  background-color: var(--card-glass);
  padding: 2.2rem 2vw;
  border-radius: 1.5rem;
  box-shadow: var(--shadow);
  border: 2.5px solid var(--card-border);
  backdrop-filter: blur(20px) saturate(1.4);
  -webkit-backdrop-filter: blur(20px) saturate(1.4);
  animation: fadein 0.7s;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

#main-content, #sidebar {
  width: 100%;
  margin-bottom: 0;
}
@media (min-width: 900px) {
  #app {
    flex-direction: row;
    gap: 3rem;
    padding: 2.5rem 3vw;
    align-items: flex-start;
  }

#main-content {
  flex: 2 1 600px;
  min-width: 0;
}

#sidebar {
  flex: 1 1 320px;
  min-width: 0;
  margin-bottom: 2rem;
}
}


/* ===== TYPOGRAPHY ===== */
h1, h2, h3 {
  font-weight: 600;
  margin-top: 0;
  margin-bottom: 1rem;
}

h1 {
  font-size: clamp(1.5rem, 4vw, 2.4rem);
  color: var(--primary);
  letter-spacing: -1px;
  background: linear-gradient(90deg, #2563eb 40%, #60a5fa 100%);
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

h2 {
  font-size: clamp(1.1rem, 2.5vw, 1.5rem);
  color: var(--text);
}

h3 {
  font-size: clamp(1rem, 2vw, 1.15rem);
  color: var(--muted);
}

/* ===== FORMS ===== */
form {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
  animation: fadeinup 0.7s;
}

input[type="text"],
input[type="number"],
select {
  width: 100%;
  padding: 0.8rem 1rem;
  border: 2px solid var(--border);
  border-radius: var(--border-radius-small);
  font-size: 1rem;
  background: rgba(255,255,255,0.9);
  backdrop-filter: blur(10px);
  transition: all var(--transition);
  box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

input:focus, select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99,102,241,0.1), 0 4px 8px rgba(0,0,0,0.1);
  background: rgba(255,255,255,0.95);
  transform: translateY(-1px);
}

input[type="checkbox"] {
  width: 1.2rem;
  height: 1.2rem;
  accent-color: var(--primary);
  cursor: pointer;
  transition: all var(--transition);
}

input[type="checkbox"]:checked {
  transform: scale(1.1);
}

/* ===== BUTTONS ===== */
button {
  padding: 0.8rem 1.5rem;
  border: none;
  border-radius: var(--border-radius);
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  color: #fff;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: all var(--transition);
  box-shadow: var(--shadow-light);
  will-change: transform;
  position: relative;
  overflow: hidden;
}

button::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  transition: left 0.5s;
}

button:hover::before {
  left: 100%;
}

button:hover, button:focus {
  background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary) 100%);
  transform: translateY(-2px);
  box-shadow: var(--shadow-medium);
}

button[disabled] {
  background: var(--border);
  color: var(--muted);
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

button[disabled]::before {
  display: none;
}

/* ===== GROUP SECTION ===== */
#group-section {
  margin-bottom: 2rem;
}

#group-select {
  margin: 0.5rem 0;
}

#delete-group-btn, #edit-group-btn {
  background: linear-gradient(135deg, var(--danger) 0%, #f97316 100%);
  color: #fff;
  margin-left: 0.5rem;
  padding: 0.6rem 1.2rem;
  font-size: 0.9rem;
  border-radius: var(--border-radius-small);
  transition: all var(--transition);
}

#edit-group-btn {
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-light) 100%);
  color: #1e293b;
}

#delete-group-btn:hover {
  background: linear-gradient(135deg, #dc2626 0%, var(--danger) 100%);
  transform: translateY(-1px);
  box-shadow: var(--shadow-medium);
}

#edit-group-btn:hover {
  background: linear-gradient(135deg, var(--accent-light) 0%, var(--accent) 100%);
  transform: translateY(-1px);
  box-shadow: var(--shadow-medium);
}

/* ===== LISTS ===== */
ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

li {
  background: linear-gradient(135deg, rgba(255,255,255,0.7) 0%, rgba(255,255,255,0.5) 100%);
  margin: 0.5rem 0;
  padding: 1.2rem;
  border-radius: var(--border-radius-large);
  border: 2px solid var(--card-border);
  box-shadow: var(--shadow-light);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  position: relative;
  animation: fadeinup 0.7s;
  min-width: 0;
  transition: all var(--transition);
  backdrop-filter: blur(16px);
}

li:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-medium);
  border-color: rgba(99,102,241,0.3);
}

li::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--primary) 0%, var(--primary-light) 50%, var(--accent) 100%);
  border-radius: var(--border-radius-large) var(--border-radius-large) 0 0;
  opacity: 0;
  transition: opacity var(--transition);
}

li:hover::before {
  opacity: 1;
}

/* ===== EXPENSE BUTTONS ===== */
.edit-expense-btn, .delete-expense-btn {
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-light) 100%);
  color: #1e293b;
  font-size: 0.9rem;
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius-small);
  margin-right: 0.5rem;
  margin-top: 0.5rem;
  border: none;
  transition: all var(--transition);
}

.edit-expense-btn:hover {
  background: linear-gradient(135deg, var(--accent-light) 0%, var(--accent) 100%);
  transform: translateY(-1px);
  box-shadow: var(--shadow-light);
}

.delete-expense-btn {
  background: linear-gradient(135deg, var(--danger) 0%, #f97316 100%);
  color: #fff;
}

.delete-expense-btn:hover {
  background: linear-gradient(135deg, #dc2626 0%, var(--danger) 100%);
  transform: translateY(-1px);
  box-shadow: var(--shadow-light);
}

/* ===== SECTIONS ===== */
#settle-up-section {
  margin: 2rem 0;
}

/* ===== MODALS ===== */
#modal-overlay {
  background: rgba(0,0,0,0.6) !important;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

#edit-expense-modal, #confirm-delete-modal, #add-expense-modal, #settlement-modal, #edit-group-modal {
  box-shadow: var(--shadow-heavy);
  border: 2.5px solid var(--card-border);
  background: var(--card-glass);
  backdrop-filter: blur(24px) saturate(1.4);
  -webkit-backdrop-filter: blur(24px) saturate(1.4);
  max-width: 600px;
  width: 95%;
  min-width: 0;
  transform-origin: center;
  will-change: transform, opacity;
  border-radius: var(--border-radius-large);
}

#edit-expense-modal h3, #confirm-delete-modal h3, #add-expense-modal h3, #settlement-modal h3, #edit-group-modal h3 {
  margin-top: 0;
  margin-bottom: 1.5rem;
  color: var(--text);
  font-size: 1.5rem;
  font-weight: 600;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

#edit-expense-modal form, #confirm-delete-modal form, #add-expense-modal form, #edit-group-modal form {
  gap: 1rem;
}

#edit-expense-modal button, #confirm-delete-modal button, #add-expense-modal button, #edit-group-modal button {
  margin-right: 0.5rem;
}

.modal-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  color: var(--muted);
  font-size: 1.5rem;
  font-weight: bold;
  cursor: pointer;
  transition: all var(--transition);
  width: 2rem;
  height: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: rgba(99,102,241,0.1);
}

.modal-close:hover {
  color: var(--danger);
  background: rgba(239,68,68,0.1);
  transform: rotate(90deg);
}

/* ===== TOASTS ===== */
#toast-container {
  position: fixed;
  top: 1.5rem;
  right: 1.5rem;
  z-index: 2000;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.toast {
  background: var(--card-glass);
  color: var(--text);
  border: 2px solid var(--card-border);
  border-left: 5px solid var(--primary);
  padding: 1rem 1.5rem;
  border-radius: var(--border-radius-large);
  box-shadow: var(--shadow-medium);
  font-size: 1rem;
  min-width: 220px;
  animation: toastSlideIn 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
  backdrop-filter: blur(14px) saturate(1.3);
  -webkit-backdrop-filter: blur(14px) saturate(1.3);
  transform-origin: top right;
}

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

/* ===== ANIMATIONS ===== */
@keyframes fadein {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes fadeinup {
  from { 
    opacity: 0; 
    transform: translateY(24px); 
  }
  to { 
    opacity: 1; 
    transform: translateY(0); 
  }
}

@keyframes popin {
  from { 
    opacity: 0; 
    transform: scale(0.92); 
  }
  to { 
    opacity: 1; 
    transform: scale(1); 
  }
}

@keyframes modalSlideIn {
  from { 
    opacity: 0; 
    transform: translateY(-20px) scale(0.95); 
  }
  to { 
    opacity: 1; 
    transform: translateY(0) scale(1); 
  }
}

@keyframes toastSlideIn {
  from { 
    opacity: 0; 
    transform: translateX(100%) scale(0.9); 
  }
  to { 
    opacity: 1; 
    transform: translateX(0) scale(1); 
  }
}

/* ===== LOADING ===== */
#loading-spinner {
  display: none;
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 3000;
}

.spinner {
  border: 4px solid var(--card-border);
  border-top: 4px solid var(--primary);
  border-radius: 50%;
  width: 48px;
  height: 48px;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

/* ===== MEMBER PAID SECTION ===== */
.member-paid-item {
  display: flex;
  align-items: center;
  gap: 0.7em;
  margin-bottom: 0.7em;
}

.member-avatar {
  width: 2.1em;
  height: 2.1em;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 1.1em;
  color: #fff;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  box-shadow: 0 2px 8px rgba(99,102,241,0.3);
  flex-shrink: 0;
  user-select: none;
  transition: all var(--transition);
}

.member-avatar:hover {
  transform: scale(1.05);
  box-shadow: 0 4px 12px rgba(99,102,241,0.4);
}

.member-paid-amount {
  font-weight: 600;
  font-size: 1em;
  margin-left: 0.5em;
  color: var(--primary);
  text-shadow: 0 1px 2px rgba(99,102,241,0.1);
}

#member-paid-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 0.7em 1em;
  padding: 0;
  margin: 0;
  align-items: flex-start;
}

/* ===== SETTLEMENT SECTION ===== */
#settle-up-section .all-settled {
  font-size: 1.2em;
  color: #22c55e;
  display: flex;
  align-items: center;
  gap: 0.4em;
  margin: 0.7em 0;
}

#settlement-list {
  max-height: 300px;
  overflow-y: auto;
  margin: 1rem 0;
}

.settlement-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.8rem;
  margin: 0.5rem 0;
  background: rgba(255,255,255,0.7);
  border-radius: var(--border-radius);
  border: 1px solid var(--border);
}

.settlement-item.settled {
  background: rgba(34,197,94,0.1);
  border-color: var(--success);
}

#settlement-checkbox {
  margin-right: 0.8rem;
}

/* ===== ACTION BUTTONS ===== */
#add-expense-btn, #settlement-btn {
  padding: 0.6rem 1rem;
  border: none;
  border-radius: var(--border-radius);
  color: #fff;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background var(--transition), box-shadow var(--transition), transform 0.15s;
  box-shadow: var(--shadow-light);
  will-change: transform;
}

#add-expense-btn:hover, #settlement-btn:hover {
  transform: translateY(-1px) scale(1.02);
  box-shadow: var(--shadow-medium);
}

/* ===== CONFETTI ===== */
.confetti {
  pointer-events: none;
  position: fixed;
  top: 0; left: 0; width: 100vw; height: 100vh;
  z-index: 9999;
  overflow: hidden;
}

.confetti-piece {
  position: absolute;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  opacity: 0.8;
  animation: confetti-fall 2.2s cubic-bezier(.4,0,.2,1) forwards;
}

@keyframes confetti-fall {
  0% { transform: translateY(-40px) scale(1); opacity: 1; }
  80% { opacity: 1; }
  100% { transform: translateY(100vh) scale(0.7); opacity: 0; }
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 900px) {
  
  #main-content, #sidebar {
    width: 100%;
    margin-bottom: 0;
  }
}

@media (max-width: 600px) {

  
  .toast {
    min-width: 140px;
    padding: 0.7rem 1rem;
    font-size: 0.95rem;
  }
  
  form {
    gap: 0.5rem;
  }
  
  li {
    padding: 0.7rem;
  }
  
  #add-expense-modal, #settlement-modal, #edit-expense-modal, #confirm-delete-modal, #edit-group-modal {
    padding: 1.1rem;
    min-width: 0;
    max-width: 98vw;
    width: 95%;
  }
}