@import url("https://fonts.googleapis.com/css2?family=Nunito:wght@400;600;700;800&display=swap");

:root {
  --bg: #f6f7fb;
  --primary: #3b6ef5;
  --primary-dark: #2d59cc;
  --accent: #ffb703;
  --text: #1c1f2a;
  --muted: #5a6272;
  --card: #ffffff;
  --danger: #e63946;
  --shadow: 0 18px 40px rgba(30, 42, 75, 0.12);
  --radius: 18px;
  --card-width: 200px;
  --card-height: 280px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Nunito", sans-serif;
  background: var(--bg);
  color: var(--text);
}

.app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.top-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 24px 6vw;
  background: #ffffff;
  box-shadow: 0 8px 24px rgba(30, 42, 75, 0.08);
  position: sticky;
  top: 0;
  z-index: 10;
}

.brand {
  display: flex;
  gap: 18px;
  align-items: center;
}

.brand-icon {
  font-size: 38px;
}

.brand h1 {
  margin: 0;
  font-size: 28px;
}

.brand p {
  margin: 4px 0 0;
  color: var(--muted);
}

.section {
  padding: 32px 6vw 56px;
}

.hidden {
  display: none;
}

.landing-hero {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 40px;
  align-items: center;
}

.landing-text h2 {
  font-size: 48px;
  margin: 0 0 12px;
}

.lead {
  font-size: 20px;
  color: var(--muted);
}

.landing-features {
  display: grid;
  gap: 16px;
  margin: 28px 0;
}

.feature-card {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 20px;
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  font-size: 18px;
}

.feature-card span {
  font-size: 28px;
}

.landing-illustration {
  text-align: center;
}

.card-stack {
  position: relative;
  width: 220px;
  height: 220px;
  margin: 0 auto 16px;
}

.floating-card {
  position: absolute;
  width: 140px;
  height: 180px;
  border-radius: 16px;
  background: var(--card);
  box-shadow: var(--shadow);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 48px;
  font-weight: 700;
  color: var(--primary);
  animation: float 3.6s ease-in-out infinite;
}

.floating-card:nth-child(1) {
  left: 10px;
  top: 20px;
  transform: rotate(-6deg);
}

.floating-card:nth-child(2) {
  right: 0;
  top: 0;
  animation-delay: 0.3s;
  transform: rotate(5deg);
}

.floating-card:nth-child(3) {
  left: 40px;
  bottom: 0;
  animation-delay: 0.6s;
  transform: rotate(-2deg);
}

.caption {
  color: var(--muted);
  font-size: 18px;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 24px;
}

.panel {
  display: none;
  animation: fadeIn 0.4s ease;
}

.panel.active {
  display: block;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.card h3 {
  margin-top: 0;
}

.cards {
  display: grid;
  gap: 16px;
}

.groups {
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
}

#groups-result {
  padding: 18px;
  border-radius: 18px;
  background: linear-gradient(160deg, #e7ecff, #f6f7fb);
  border: 2px solid rgba(59, 110, 245, 0.15);
  min-height: 260px;
  perspective: 1000px;
}

label {
  display: block;
  margin: 16px 0 8px;
  font-weight: 700;
}

input,
textarea,
select {
  width: 100%;
  border-radius: 12px;
  border: 1px solid #d8dce7;
  padding: 12px 14px;
  font-size: 16px;
  font-family: inherit;
}

textarea {
  resize: vertical;
  min-height: 140px;
}

.row {
  display: flex;
  gap: 12px;
  align-items: center;
  margin-top: 18px;
  flex-wrap: wrap;
}

.btn {
  border: none;
  border-radius: 14px;
  padding: 12px 20px;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
  background: #e8edf9;
  color: var(--text);
}

.btn:active {
  transform: scale(0.97);
}

.btn.primary {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 12px 24px rgba(59, 110, 245, 0.32);
}

.btn.primary:hover {
  background: var(--primary-dark);
}

.btn.big {
  font-size: 20px;
  padding: 16px 26px;
}

.btn.ghost {
  background: transparent;
  border: 2px solid #e0e6f5;
}

.btn.tab {
  background: #ffffff;
  border: 2px solid transparent;
}

.btn.tab.active {
  border-color: var(--primary);
  color: var(--primary);
}

.btn.danger {
  background: var(--danger);
  color: #fff;
}

.hint {
  color: var(--muted);
  margin-top: 12px;
}

.class-card {
  border: 2px solid #eef1f8;
  padding: 16px;
  border-radius: 16px;
  background: #fbfcff;
}

.class-card h4 {
  margin: 0 0 8px;
}

.class-card .actions {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.group-card {
  position: relative;
  width: var(--card-width, 200px);
  height: var(--card-height, 280px);
  min-width: var(--card-width, 200px);
  min-height: var(--card-height, 280px);
  display: block;
  overflow: hidden;
  border-radius: 16px;
  background: transparent;
}

.group-card-animated {
  opacity: 0;
  transform: translateY(-160px) rotate(-6deg);
  animation: dealCard 0.7s ease forwards;
  animation-delay: var(--delay, 0s);
}

.group-card-inner {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  min-height: 100%;
  transform-style: preserve-3d;
  animation: flipCard 0.7s ease forwards;
  animation-delay: calc(var(--delay, 0s) + 0.55s);
}

.group-card-face {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border-radius: 16px;
  padding: 12px;
  background: linear-gradient(140deg, #ffffff, #f1f5ff);
  box-shadow: var(--shadow);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.group-card-front {
  display: block;
  color: var(--primary);
  overflow: hidden;
  width: 100%;
  height: 100%;
  background: #ffffff;
}

.group-card-front::after {
  content: "";
  position: absolute;
  inset: 10px;
  border-radius: 12px;
  border: 10px solid #ffffff;
  background-color: #7d8597;
  background-image: repeating-linear-gradient(
      45deg,
      transparent,
      transparent 10px,
      rgba(199, 206, 219, 0.7) 10px,
      rgba(199, 206, 219, 0.7) 11px
    ),
    repeating-linear-gradient(
      -45deg,
      transparent,
      transparent 10px,
      rgba(199, 206, 219, 0.7) 10px,
      rgba(199, 206, 219, 0.7) 11px
    );
  background-size: 20px 20px;
}

.group-card-front h4,
.group-card-front p {
  position: relative;
  z-index: 1;
}

.group-card-back {
  transform: rotateY(180deg);
  background: linear-gradient(140deg, #ffffff, #f1f5ff);
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  justify-content: flex-start;
  gap: 8px;
  overflow: auto;
}

.group-card-face h4 {
  margin-top: 0;
}

.group-card-face ul {
  padding-left: 18px;
  margin: 0;
  position: relative;
  z-index: 1;
}

.group-list {
  opacity: 0;
  transform: translateY(6px);
  animation: revealList 0.45s ease forwards;
  animation-delay: calc(var(--delay, 0s) + 0.75s);
}

.picker-animation {
  background: #f1f4ff;
  border-radius: 16px;
  padding: 18px;
  font-size: 20px;
  text-align: center;
  margin-bottom: 16px;
  min-height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}

.picker-result {
  font-size: 28px;
  font-weight: 800;
  color: var(--primary);
  text-align: center;
}

.shuffle-area {
  background: linear-gradient(140deg, #fdfbff, #eef3ff);
  border-radius: 16px;
  padding: 20px;
  min-height: 220px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  animation: glowPulse 1.8s ease-in-out infinite;
}

.shuffle-title {
  font-weight: 800;
  color: var(--primary);
  text-align: center;
  font-size: 18px;
}

.shuffle-cards {
  position: relative;
  width: calc(var(--card-width, 200px) + 20px);
  height: calc(var(--card-height, 280px) + 20px);
}

.shuffle-card {
  position: absolute;
  width: var(--card-width, 200px);
  height: var(--card-height, 280px);
  min-width: var(--card-width, 200px);
  min-height: var(--card-height, 280px);
  border-radius: 16px;
  background: #ffffff;
  box-shadow: 0 18px 36px rgba(59, 110, 245, 0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 36px;
  font-weight: 800;
  color: var(--primary);
  transition: left 0.8s ease-in-out;
  border: 3px solid #1c1f2a;
  top: 0;
  left: 0;
  z-index: calc(20 - var(--index, 0));
  overflow: hidden;
}

.shuffle-card.shuffle-moving {
  transition: none;
  animation: shuffleDeal 1.2s ease-in-out forwards;
  z-index: 30;
}

.shuffle-letter {
  position: relative;
  z-index: 2;
  display: none;
}

.shuffle-face {
  position: absolute;
  inset: 0;
  border-radius: 16px;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: center;
}

.shuffle-background {
  width: calc(var(--card-width, 200px) - 20px);
  height: calc(var(--card-height, 280px) - 20px);
  border-radius: 12px;
  border: 10px solid #ffffff;
  background-color: #7d8597;
  background-image: repeating-linear-gradient(
      45deg,
      transparent,
      transparent 10px,
      #c7cedb 10px,
      #c7cedb 11px
    ),
    repeating-linear-gradient(
      -45deg,
      transparent,
      transparent 10px,
      #c7cedb 10px,
      #c7cedb 11px
    );
  background-size: 20px 20px;
}

.danger {
  border: 2px solid rgba(230, 57, 70, 0.2);
}

@keyframes float {
  0%,
  100% {
    transform: translateY(0) rotate(-4deg);
  }
  50% {
    transform: translateY(-12px) rotate(2deg);
  }
}

@keyframes popIn {
  from {
    opacity: 0;
    transform: translateY(10px) scale(0.98);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}


@keyframes glowPulse {
  0%,
  100% {
    box-shadow: 0 12px 26px rgba(59, 110, 245, 0.18);
  }
  50% {
    box-shadow: 0 18px 40px rgba(255, 183, 3, 0.28);
  }
}

@keyframes dealCard {
  0% {
    opacity: 0;
    transform: translateY(-180px) rotate(-10deg);
  }
  70% {
    opacity: 1;
    transform: translateY(8px) rotate(4deg);
  }
  100% {
    opacity: 1;
    transform: translateY(0) rotate(0deg);
  }
}

@keyframes flipCard {
  0% {
    transform: rotateY(0deg);
  }
  100% {
    transform: rotateY(180deg);
  }
}

@keyframes shuffleDeal {
  0% {
    transform: translate(0, 0) rotate(0deg);
  }
  40% {
    transform: translate(-60px, 4px) rotate(-6deg);
  }
  70% {
    transform: translate(10px, 10px) rotate(2deg);
  }
  100% {
    transform: translate(0, 0) rotate(0deg);
  }
}

@keyframes revealList {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 900px) {
  .top-bar {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }
}