/* style.css - Zombie Fraction Defense */

:root {
  --bg-dark: hsl(220, 30%, 8%);
  --bg-mid: hsl(220, 25%, 14%);
  --bg-card: hsl(220, 20%, 18%);
  --surface: hsl(220, 18%, 22%);
  --border: hsl(220, 15%, 28%);
  --text: hsl(60, 10%, 90%);
  --text-sub: hsl(220, 10%, 55%);
  --red: hsl(0, 80%, 55%);
  --red-glow: hsl(0, 90%, 45%);
  --green: hsl(120, 60%, 45%);
  --green-light: hsl(120, 60%, 25%);
  --amber: hsl(40, 95%, 55%);
  --purple: hsl(270, 70%, 55%);
  --blue: hsl(210, 80%, 55%);
  --zombie-green: hsl(100, 50%, 40%);
  --blood-red: hsl(0, 85%, 35%);
  --font: 'Outfit', 'Noto Sans KR', sans-serif;
  --font-creepy: 'Creepster', 'Outfit', cursive;
  --radius: 14px;
  --transition: all 0.25s cubic-bezier(0.4,0,0.2,1);
}

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

body {
  font-family: var(--font);
  background: var(--bg-dark);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

/* Screen system */
.screen { display: none; min-height: 100vh; position: relative; }
.screen.active { display: flex; flex-direction: column; }

/* ===== START SCREEN ===== */
#screen-start {
  align-items: center; justify-content: center;
  background: linear-gradient(180deg, hsl(220,30%,6%) 0%, hsl(150,20%,8%) 50%, hsl(220,30%,4%) 100%);
  overflow: hidden;
}

.start-overlay {
  position: absolute; inset: 0;
  background: radial-gradient(ellipse at 50% 80%, rgba(100,200,100,0.06) 0%, transparent 60%);
}

.start-content {
  position: relative; z-index: 2;
  display: flex; flex-direction: column; align-items: center; gap: 36px;
  padding: 24px;
}

.title-group { text-align: center; }
.title-zombie { font-size: 5rem; display: block; animation: zombieWalk 1.5s infinite; }
.game-title {
  font-family: var(--font-creepy);
  font-size: 3rem; color: var(--green);
  text-shadow: 0 0 20px rgba(74,222,128,0.5), 0 0 40px rgba(74,222,128,0.2);
  letter-spacing: 3px;
}
.game-subtitle { font-size: 1rem; color: var(--text-sub); margin-top: 6px; }

.start-form {
  background: var(--bg-card); border-radius: var(--radius);
  padding: 28px 24px; width: 100%; max-width: 400px;
  display: flex; flex-direction: column; gap: 20px;
  border: 1px solid var(--border);
  box-shadow: 0 10px 40px rgba(0,0,0,0.4);
}

.form-row { display: flex; flex-direction: column; gap: 8px; }
.form-row label { font-size: 0.8rem; font-weight: 700; color: var(--text-sub); text-transform: uppercase; letter-spacing: 1px; }

input[type="text"] {
  padding: 12px 16px; border-radius: 10px;
  border: 2px solid var(--border); background: var(--surface);
  color: var(--text); font-size: 1rem; outline: none;
  transition: var(--transition);
}
input[type="text"]:focus { border-color: var(--green); }

.diff-btns { display: flex; gap: 8px; }
.diff-btn {
  flex: 1; padding: 10px 8px; border-radius: 10px;
  border: 2px solid var(--border); background: var(--surface);
  color: var(--text); font-size: 0.85rem; font-weight: 700;
  cursor: pointer; transition: var(--transition); text-align: center;
}
.diff-btn:hover { border-color: var(--green); }
.diff-btn.active { border-color: var(--green); background: var(--green-light); color: var(--green); }

.btn-play {
  padding: 16px; border: none; border-radius: 12px;
  background: linear-gradient(135deg, var(--green), hsl(140,60%,35%));
  color: white; font-size: 1.2rem; font-weight: 800;
  cursor: pointer; transition: var(--transition);
  display: flex; align-items: center; justify-content: center; gap: 8px;
  box-shadow: 0 4px 20px rgba(74,222,128,0.3);
}
.btn-play:hover { transform: translateY(-2px); box-shadow: 0 6px 25px rgba(74,222,128,0.4); }
.btn-play-icon { font-size: 1.4rem; }

/* Background walking zombies */
.bg-zombie {
  position: absolute; font-size: 3rem; opacity: 0.15;
  animation: bgZombieWalk 12s linear infinite;
}
.z1 { bottom: 10%; animation-duration: 14s; animation-delay: 0s; }
.z2 { bottom: 15%; animation-duration: 18s; animation-delay: 4s; font-size: 2.5rem; }
.z3 { bottom: 8%; animation-duration: 22s; animation-delay: 8s; font-size: 2rem; }

@keyframes bgZombieWalk {
  0% { left: -10%; } 100% { left: 110%; }
}

/* ===== GAME SCREEN ===== */
#screen-game {
  background: var(--bg-dark);
  height: 100vh; max-height: 100vh;
  overflow: hidden;
}

/* HUD */
.hud {
  display: flex; align-items: center; justify-content: space-between;
  padding: 10px 16px; background: rgba(0,0,0,0.6);
  border-bottom: 2px solid var(--border); z-index: 10;
  flex-shrink: 0;
}
.hud-lives { display: flex; gap: 4px; }
.heart { font-size: 1.3rem; transition: var(--transition); }
.heart.lost { opacity: 0.2; filter: grayscale(1); transform: scale(0.8); }

.hud-wave {
  font-family: var(--font-creepy); font-size: 1.2rem;
  color: var(--amber); letter-spacing: 2px;
}

.hud-score, .hud-kills {
  display: flex; flex-direction: column; align-items: center;
}
.score-label, .kills-label { font-size: 0.6rem; font-weight: 700; color: var(--text-sub); text-transform: uppercase; letter-spacing: 1px; }
.score-val, .kills-val { font-size: 1.1rem; font-weight: 900; color: var(--amber); }

/* Stage */
.stage {
  flex: 1; position: relative; overflow: hidden;
  background: linear-gradient(180deg,
    hsl(220,30%,6%) 0%,
    hsl(200,20%,10%) 40%,
    hsl(130,15%,12%) 70%,
    hsl(100,15%,10%) 100%
  );
  min-height: 0;
}

.stage-ground {
  position: absolute; bottom: 0; left: 0; right: 0; height: 30%;
  background: linear-gradient(180deg, hsl(100,10%,12%) 0%, hsl(80,10%,8%) 100%);
  border-top: 2px solid hsl(100,15%,18%);
}

.stage-fog {
  position: absolute; bottom: 25%; left: 0; right: 0; height: 60px;
  background: linear-gradient(180deg, transparent, rgba(100,150,100,0.06), transparent);
  animation: fogDrift 8s ease-in-out infinite alternate;
}

@keyframes fogDrift {
  0% { transform: translateX(-20px); opacity: 0.4; }
  100% { transform: translateX(20px); opacity: 0.8; }
}

/* Zombie */
.zombie-zone {
  position: absolute; top: 0; left: 0; right: 0; bottom: 15%;
  display: flex; justify-content: center;
  pointer-events: none;
}

.zombie { position: absolute; top: -150px; left: 50%; transform: translateX(-50%); }

.zombie-body {
  display: flex; flex-direction: column; align-items: center;
  transform-origin: center center;
}

.zombie-body.walking {
  animation: zombieWalkLoop 0.5s steps(2) infinite;
}

.zombie-body.shot {
  animation: zombieShot 0.5s ease-out forwards;
}

.zombie-body.attack {
  animation: zombieAttack 0.5s ease-out forwards;
}

.zombie-sign {
  background: rgba(0,0,0,0.8); border: 2px solid var(--zombie-green);
  border-radius: 10px; padding: 12px 18px;
  margin-bottom: 6px; min-width: 160px; text-align: center;
  box-shadow: 0 0 15px rgba(74,222,128,0.2);
  position: relative;
  transition: all 0.3s ease;
}
.zombie.targeted .zombie-sign {
  border-color: var(--red-glow);
  box-shadow: 0 0 25px rgba(239,68,68,0.6);
  transform: scale(1.1);
}
.zombie-sign::after {
  content: ''; position: absolute; bottom: -8px; left: 50%; transform: translateX(-50%);
  border-left: 8px solid transparent; border-right: 8px solid transparent;
  border-top: 8px solid var(--zombie-green);
  transition: border-top-color 0.3s;
}
.zombie.targeted .zombie-sign::after {
  border-top-color: var(--red-glow);
}

.zombie-sprite { font-size: 4.5rem; line-height: 1; filter: drop-shadow(0 0 8px rgba(100,200,100,0.3)); }

/* Fraction rendering in sign */
.frac {
  display: inline-flex; flex-direction: column; align-items: center;
  font-size: 1.3rem; font-weight: 800; color: var(--text); line-height: 1;
}
.frac-num { padding-bottom: 3px; }
.frac-bar { width: 100%; min-width: 24px; height: 2.5px; background: var(--text); border-radius: 2px; }
.frac-den { padding-top: 3px; }
.op-sym { font-size: 1.4rem; font-weight: 900; color: var(--green); margin: 0 6px; }
.eq-sym { font-size: 1.4rem; font-weight: 900; color: var(--text-sub); margin: 0 6px; }
.q-mark {
  display: inline-flex; align-items: center; justify-content: center;
  width: 40px; height: 50px; border: 2px dashed var(--amber);
  border-radius: 8px; font-size: 1.3rem; font-weight: 900; color: var(--amber);
  background: rgba(251,191,36,0.1);
}

/* Muzzle flash & Bullet */
.muzzle-flash {
  position: absolute; bottom: 15%; left: 50%; transform: translate(-50%, 50%);
  font-size: 4rem; opacity: 0; z-index: 5; pointer-events: none;
}
.muzzle-flash.fire {
  animation: muzzleFlash 0.3s ease-out forwards;
}

.bullet {
  position: absolute; font-size: 2.5rem;
  z-index: 6; pointer-events: none;
  filter: drop-shadow(0 0 10px rgba(255,100,0,0.8));
  transition: all 0.4s linear; /* dynamic translation */
}

/* Player */
.player {
  position: absolute; bottom: 5%; left: 50%; transform: translateX(-50%);
  z-index: 5;
  display: flex; flex-direction: column; align-items: center; justify-content: flex-end;
}
.player-avatar {
  display: flex; flex-direction: column; align-items: center;
  z-index: 2; position: relative;
}
.player-face {
  font-size: 3rem; line-height: 1; z-index: 2; position: relative;
}
.player-body {
  font-size: 3.5rem; line-height: 0.8; margin-top: -10px; z-index: 1;
}
.player-gun {
  position: absolute; right: -40px; top: 15px;
  font-size: 2.8rem; transform: scaleX(-1) rotate(60deg);
  filter: drop-shadow(0 0 10px rgba(255,255,255,0.2));
  transition: transform 0.1s;
  z-index: 3;
}
.player-gun.recoil {
  animation: recoil 0.15s ease-out;
}



/* Ammo Panel (choices) */
.ammo-panel {
  display: grid; grid-template-columns: 1fr 1fr;
  gap: 10px; padding: 14px 16px;
  background: rgba(0,0,0,0.7);
  border-top: 2px solid var(--border);
  flex-shrink: 0;
}

.ammo-btn {
  display: flex; align-items: center; justify-content: center;
  gap: 8px; padding: 16px 12px;
  border-radius: 12px; border: 2px solid var(--border);
  background: var(--surface); color: var(--text);
  cursor: pointer; transition: var(--transition);
  min-height: 64px; position: relative;
  font-family: var(--font);
}
.ammo-btn::before {
  content: '🔹'; font-size: 0.8rem; position: absolute;
  top: 6px; left: 8px;
}
.ammo-btn:hover { border-color: var(--green); background: var(--green-light); }
.ammo-btn:active { transform: scale(0.96); }
.ammo-btn.correct {
  border-color: var(--green); background: var(--green-light);
  box-shadow: 0 0 20px rgba(74,222,128,0.3);
}
.ammo-btn.correct::before { content: '✅'; }
.ammo-btn.wrong {
  border-color: var(--red); background: hsla(0,80%,55%,0.15);
}
.ammo-btn.wrong::before { content: '❌'; }
.ammo-btn.disabled { pointer-events: none; opacity: 0.5; }

.ammo-btn .frac { font-size: 1.15rem; }

/* Combo popup */
.combo-popup {
  position: fixed; top: 50%; left: 50%; transform: translate(-50%,-50%);
  z-index: 100; pointer-events: none;
}
.combo-popup span {
  font-family: var(--font-creepy); font-size: 2.5rem;
  color: var(--amber); text-shadow: 0 0 20px rgba(251,191,36,0.6);
  animation: comboFlash 0.8s ease-out forwards;
}

/* Points floating */
.float-points {
  position: absolute; z-index: 50; pointer-events: none;
  font-size: 1.3rem; font-weight: 900; color: var(--amber);
  text-shadow: 0 0 10px rgba(251,191,36,0.5);
  animation: floatUp 1s ease-out forwards;
}

/* ===== GAME OVER ===== */
#screen-gameover {
  align-items: center; justify-content: center; padding: 20px;
  background: linear-gradient(180deg, hsl(0,20%,6%) 0%, hsl(220,30%,8%) 100%);
}

.gameover-card {
  background: var(--bg-card); border-radius: var(--radius);
  border: 1px solid var(--border); box-shadow: 0 10px 40px rgba(0,0,0,0.5);
  padding: 36px 28px; width: 100%; max-width: 450px;
  display: flex; flex-direction: column; align-items: center; gap: 20px;
  text-align: center;
}

.go-emoji { font-size: 4rem; }
.go-title {
  font-family: var(--font-creepy); font-size: 2.5rem;
  color: var(--red); text-shadow: 0 0 15px rgba(239,68,68,0.4);
  letter-spacing: 3px;
}
.go-title.survived {
  color: var(--green); text-shadow: 0 0 15px rgba(74,222,128,0.4);
}
.go-name { color: var(--text-sub); font-size: 0.95rem; margin-top: -10px; }

.go-stats { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; width: 100%; }
.go-stat {
  display: flex; flex-direction: column; align-items: center; gap: 2px;
  padding: 14px 8px; border-radius: 12px; background: var(--surface);
}
.go-stat-val { font-size: 1.5rem; font-weight: 900; color: var(--amber); }
.go-stat-label { font-size: 0.7rem; color: var(--text-sub); font-weight: 600; }

/* Review */
.go-review { width: 100%; text-align: left; max-height: 200px; overflow-y: auto; }
.go-review h3 { font-size: 1rem; font-weight: 800; margin-bottom: 10px; color: var(--text); }
.go-review-list { display: flex; flex-direction: column; gap: 8px; }
.review-item {
  padding: 10px 14px; border-radius: 10px;
  background: var(--surface); border: 1px solid var(--border);
}
.review-q { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; margin-bottom: 4px; }
.review-q .frac { font-size: 0.95rem; }
.review-ans { font-size: 0.8rem; color: var(--text-sub); }
.review-ans strong { color: var(--green); }

.go-actions { display: flex; gap: 10px; width: 100%; }
.btn-retry, .btn-home {
  flex: 1; padding: 14px; border: none; border-radius: 12px;
  font-size: 1rem; font-weight: 700; cursor: pointer; transition: var(--transition);
}
.btn-retry { background: var(--green); color: white; }
.btn-retry:hover { background: hsl(120,60%,35%); }
.btn-home { background: var(--surface); color: var(--text); border: 2px solid var(--border); }
.btn-home:hover { border-color: var(--green); }

/* ===== ANIMATIONS ===== */
@keyframes zombieWalk {
  0%,100% { transform: translateY(0) rotate(-2deg); }
  50% { transform: translateY(-6px) rotate(2deg); }
}

@keyframes zombieWalkLoop {
  0% { transform: translateX(-3px) rotate(-1deg); }
  50% { transform: translateX(3px) rotate(1deg); }
}

@keyframes zombieApproach {
  0% { transform: scale(0.4) translateY(-40px); opacity: 0; }
  100% { transform: scale(1) translateY(0); opacity: 1; }
}

@keyframes zombieShot {
  0% { transform: scale(1) rotate(0deg); filter: brightness(2) hue-rotate(-50deg); }
  100% { transform: scale(1.2) rotate(25deg) translateY(-30px); opacity: 0; filter: brightness(0); }
}

@keyframes zombieAttack {
  0% { transform: scale(1); }
  50% { transform: scale(1.3) translateY(20px); filter: brightness(1.5) drop-shadow(0 0 20px red); }
  100% { transform: scale(1) translateY(0); opacity: 0; }
}

@keyframes muzzleFlash {
  0% { opacity: 1; transform: translate(-50%, 50%) scale(0.5); }
  50% { opacity: 1; transform: translate(-50%, 50%) scale(1.5); }
  100% { opacity: 0; transform: translate(-50%, 50%) scale(2); }
}

@keyframes bulletFly {
  0% { transform: translate(-50%, 0) scale(1); opacity: 1; }
  100% { transform: translate(-50%, -400px) scale(0.5); opacity: 0; }
}

@keyframes recoil {
  0% { transform: scaleX(-1) rotate(60deg) translateY(0); }
  50% { transform: scaleX(-1) rotate(60deg) translateY(15px); }
  100% { transform: scaleX(-1) rotate(60deg) translateY(0); }
}

@keyframes comboFlash {
  0% { transform: scale(0.5); opacity: 0; }
  30% { transform: scale(1.3); opacity: 1; }
  100% { transform: scale(1); opacity: 0; }
}

@keyframes floatUp {
  0% { transform: translateY(0); opacity: 1; }
  100% { transform: translateY(-60px); opacity: 0; }
}

@keyframes screenShake {
  0%,100% { transform: translateX(0); }
  20% { transform: translateX(-8px); }
  40% { transform: translateX(8px); }
  60% { transform: translateX(-5px); }
  80% { transform: translateX(5px); }
}

.shake { animation: screenShake 0.4s ease-out; }

/* ===== RESPONSIVE ===== */
@media (max-width: 480px) {
  .game-title { font-size: 2.2rem; }
  .title-zombie { font-size: 3.5rem; }
  .start-form { padding: 20px 16px; }
  .hud { padding: 8px 10px; }
  .hud-wave { font-size: 1rem; }
  .heart { font-size: 1.1rem; }
  .zombie-sprite { font-size: 3.5rem; }
  .zombie-sign { padding: 8px 12px; min-width: 130px; }
  .zombie-sign .frac { font-size: 1.1rem; }
  .ammo-panel { padding: 10px 12px; gap: 8px; }
  .ammo-btn { padding: 12px 8px; min-height: 56px; }
  .ammo-btn .frac { font-size: 1rem; }
  .player-gun { font-size: 2.2rem; }
}

@media (max-height: 700px) {
  .stage { min-height: 200px; }
  .zombie-sprite { font-size: 3rem; }
  .zombie-sign { padding: 6px 10px; }
  .ammo-btn { padding: 10px 6px; min-height: 50px; }
}