:root {
      --cream: #fff8f2;
      --cream-deep: #fbefe4;
      --blush: #ffe3e8;
      --rose: #e5899c;
      --rose-deep: #c96c82;
      --plum: #4a2e38;
      --plum-soft: #7a5a63;
      --gold: #d9a75b;
      --shadow: 0 10px 30px rgba(74, 46, 56, 0.12);
      --shadow-lg: 0 20px 40px rgba(74, 46, 56, 0.18);
      --transition-speed: 0.8s;
    }

    * {
      box-sizing: border-box;
      -webkit-tap-highlight-color: transparent;
    }

    html,
    body {
      height: 100%;
      /* THÊM: Ngăn chặn scroll không mong muốn trên mobile */
      position: fixed;
      width: 100%;
      overflow: hidden;
    }

    body {
      margin: 0;
      font-family: "Quicksand", sans-serif;
      background: #000;
      color: var(--plum);
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
      /* THÊM: Ngăn chặn pull-to-refresh và các gesture khác */
      overscroll-behavior: none;
      touch-action: manipulation;
    }

    .script {
      font-family: "Dancing Script", cursive;
    }

    #stage {
      position: relative;
      width: 100%;
      height: 100vh;
      height: 100dvh;
      overflow: hidden;
      background: var(--cream);
    }

    .screen {
      position: absolute;
      inset: 0;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      text-align: center;
      padding: 32px;
      opacity: 0;
      visibility: hidden;
      pointer-events: none;
      transition:
        opacity var(--transition-speed) cubic-bezier(0.23, 1, 0.32, 1),
        visibility var(--transition-speed) cubic-bezier(0.23, 1, 0.32, 1);
      will-change: opacity, visibility;
      /* THÊM: Cho phép scroll nếu nội dung dài */
      overflow-y: auto;
      -webkit-overflow-scrolling: touch;
    }

    .reveal-names {
      font-family: "Dancing Script", cursive;
      font-weight: 700;
      font-size: 44px;
      color: var(--plum);
      margin: 0;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 14px;
    }

    .heart-icon {
      display: inline-block;
      font-size: 36px;
      background: linear-gradient(135deg, #ff6b8a, #e5597a);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
      animation: heartBeat 2s ease-in-out infinite;
      transform-origin: center;
      will-change: transform;
      filter: drop-shadow(0 2px 12px rgba(229, 137, 156, 0.5));
    }

    @keyframes heartBeat {
      0% {
        transform: scale(1);
      }

      15% {
        transform: scale(1.3);
      }

      30% {
        transform: scale(1);
      }

      45% {
        transform: scale(1.2);
      }

      70% {
        transform: scale(1);
      }

      100% {
        transform: scale(1);
      }
    }

    .screen.active {
      opacity: 1;
      visibility: visible;
      pointer-events: auto;
    }

    /* ============ SCREEN 1 ============ */
    #screen-gift {
      background:
        radial-gradient(circle at 50% 40%, var(--blush), transparent 60%),
        var(--cream);
    }

    .gift-icon {
      position: relative;
      width: 78px;
      height: 78px;
      margin-bottom: 22px;
    }

    .gift-glow {
      position: absolute;
      inset: -18px;
      border-radius: 50%;
      background: radial-gradient(circle,
          rgba(229, 137, 156, 0.45),
          transparent 70%);
      animation: glow 2s ease-in-out infinite;
    }

    @keyframes glow {

      0%,
      100% {
        transform: scale(0.9);
        opacity: 0.6;
      }

      50% {
        transform: scale(1.15);
        opacity: 1;
      }
    }

    .gift-icon svg {
      position: relative;
      width: 100%;
      height: 100%;
      fill: var(--rose-deep);
      filter: drop-shadow(0 4px 6px rgba(201, 108, 130, 0.2));
    }

    .gift-title {
      font-family: "Dancing Script", cursive;
      font-weight: 700;
      font-size: 36px;
      margin: 0 0 8px;
      letter-spacing: 0.02em;
    }

    .gift-sub {
      font-size: 14px;
      color: var(--plum-soft);
      margin: 0 0 26px;
      font-weight: 500;
    }

    .gift-bar {
      width: 120px;
      height: 4px;
      background: var(--blush);
      border-radius: 10px;
      overflow: hidden;
    }

    .gift-bar span {
      display: block;
      height: 100%;
      width: 0;
      background: var(--rose);
      border-radius: 10px;
      animation: load 2s cubic-bezier(0.4, 0, 0.2, 1) forwards;
    }

    @keyframes load {
      to {
        width: 100%;
      }
    }

    /* ============ SCREEN 2 ============ */
    #screen-envelope {
      background: var(--cream);
    }

    .env-msg {
      font-size: 15px;
      color: var(--plum-soft);
      max-width: 280px;
      margin: 0 0 30px;
      line-height: 1.7;
    }

    .env-msg b {
      color: var(--plum);
      font-weight: 700;
    }

    .arrow-down {
      width: 24px;
      height: 24px;
      margin-bottom: 16px;
      animation: bounce 1.6s ease-in-out infinite;
    }

    .arrow-down svg {
      width: 100%;
      height: 100%;
      fill: none;
      stroke: var(--rose);
      stroke-width: 2.5;
      stroke-linecap: round;
      stroke-linejoin: round;
    }

    @keyframes bounce {

      0%,
      100% {
        transform: translateY(0);
        opacity: 0.4;
      }

      50% {
        transform: translateY(10px);
        opacity: 1;
      }
    }

    .envelope-btn {
      background: none;
      border: none;
      cursor: pointer;
      padding: 0;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 18px;
      transition: transform 0.2s ease;
      min-width: 150px;
      min-height: 150px;
      justify-content: center;
      /* THÊM: Tăng vùng touch cho mobile */
      -webkit-tap-highlight-color: rgba(229, 137, 156, 0.2);
    }

    .envelope-btn:focus-visible {
      outline: 2px solid var(--rose-deep);
      outline-offset: 8px;
      border-radius: 12px;
    }

    .envelope-btn:active {
      transform: scale(0.96);
    }

    .envelope-shape {
      width: 150px;
      height: 104px;
      position: relative;
    }

    .envelope-shape svg {
      width: 100%;
      height: 100%;
    }

    .env-outline {
      fill: none;
      stroke: var(--plum);
      stroke-width: 2.4;
      stroke-linejoin: round;
      transition: stroke 0.3s ease;
    }

    .envelope-btn:hover .env-outline {
      stroke: var(--rose-deep);
    }

    .press-hint {
      font-size: 13px;
      color: var(--rose-deep);
      font-weight: 700;
      letter-spacing: 0.06em;
      text-transform: uppercase;
    }

    .env-pulse {
      animation: envPulse 2s ease-in-out infinite;
    }

    @keyframes envPulse {

      0%,
      100% {
        transform: scale(1);
      }

      50% {
        transform: scale(1.04);
      }
    }

    /* ============ SCREEN 3 - QUIZ ============ */
    #screen-quiz {
      background: linear-gradient(160deg, #fff8f2 0%, #ffe3e8 100%);
    }

    .quiz-container {
      max-width: 380px;
      width: 100%;
      background: #fff;
      padding: 36px 28px 32px;
      border-radius: 28px;
      box-shadow: var(--shadow-lg);
      text-align: center;
      position: relative;
      overflow: hidden;
      border: 1px solid rgba(229, 137, 156, 0.1);
    }

    .quiz-icon {
      font-size: 42px;
      margin-bottom: 12px;
      animation: envPulse 2s ease-in-out infinite;
    }

    .quiz-title {
      font-family: "Dancing Script", cursive;
      font-size: 30px;
      color: var(--plum);
      margin: 0 0 8px;
    }

    .quiz-desc {
      font-size: 14px;
      color: var(--plum-soft);
      margin: 0 0 24px;
      line-height: 1.5;
    }

    .quiz-form {
      display: flex;
      flex-direction: column;
      gap: 16px;
    }

    .quiz-input-wrap {
      text-align: left;
    }

    .quiz-input-wrap label {
      display: block;
      font-size: 13px;
      font-weight: 600;
      color: var(--plum);
      margin-bottom: 8px;
    }

    #quizAnswer {
      width: 100%;
      padding: 12px 16px;
      border: 2px solid var(--blush);
      border-radius: 14px;
      font-family: "Quicksand", sans-serif;
      font-size: 15px;
      outline: none;
      transition:
        border-color 0.3s ease,
        background 0.3s ease;
      background: #fafafa;
      color: var(--plum);
      /* THÊM: Ngăn zoom trên iOS */
      font-size: 16px;
    }

    #quizAnswer:focus {
      border-color: var(--rose);
      background: #fff;
      box-shadow: 0 0 0 3px rgba(229, 137, 156, 0.2);
    }

    .quiz-btn {
      width: 100%;
      background: var(--rose);
      color: #fff;
      border: none;
      padding: 14px;
      border-radius: 14px;
      font-family: "Quicksand", sans-serif;
      font-weight: 700;
      font-size: 16px;
      cursor: pointer;
      transition:
        transform 0.2s,
        background 0.2s,
        box-shadow 0.2s;
      box-shadow: 0 4px 14px rgba(229, 137, 156, 0.4);
      letter-spacing: 0.02em;
      /* THÊM: Tối ưu touch */
      touch-action: manipulation;
    }

    .quiz-btn:active {
      transform: scale(0.96);
    }

    .quiz-btn:hover {
      background: var(--rose-deep);
      box-shadow: 0 6px 18px rgba(201, 108, 130, 0.5);
    }

    .quiz-error {
      font-size: 13px;
      color: #d9534f;
      margin: 0;
      min-height: 20px;
      opacity: 0;
      visibility: hidden;
      transition: opacity 0.3s ease;
    }

    .quiz-error.show {
      opacity: 1;
      visibility: visible;
      animation: shakeError 0.4s ease-in-out;
    }

    @keyframes shakeError {

      0%,
      100% {
        transform: translateX(0);
      }

      25% {
        transform: translateX(-5px);
      }

      75% {
        transform: translateX(5px);
      }
    }

    .quiz-hint {
      margin-top: 18px;
      font-size: 12px;
      color: var(--plum-soft);
      opacity: 0.7;
      padding-top: 16px;
      border-top: 1px solid var(--blush);
    }

    /* ============ SCREEN HEART - TRÁI TIM TƯƠNG TÁC ============ */
    #screen-heart {
      background: radial-gradient(circle at center, #fff5f7 0%, #ffe3e8 100%);
      cursor: pointer;
      user-select: none;
      -webkit-user-select: none;
      padding: 20px;
      /* THÊM: Ngăn scroll khi tương tác với heart */
      touch-action: none;
    }

    .heart-interactive {
      position: relative;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 24px;
      padding: 20px;
      width: 100%;
      height: 100%;
      max-width: 500px;
      margin: 0 auto;
    }

    .heart-container {
      position: relative;
      width: 240px;
      height: 240px;
      display: flex;
      align-items: center;
      justify-content: center;
      transition: transform 0.15s ease;
      cursor: pointer;
      /* THÊM: Tối ưu cho touch */
      touch-action: none;
    }

    .heart-container.pressing {
      transform: scale(0.92);
    }

    .heart-svg {
      width: 100%;
      height: 100%;
      filter: drop-shadow(0 8px 30px rgba(201, 108, 130, 0.15));
      transition: filter 0.5s ease;
    }

    .heart-svg.filled {
      filter: drop-shadow(0 8px 45px rgba(229, 89, 122, 0.5));
    }

    /* Đường viền trái tim - đẹp hơn */
    .heart-outline {
      fill: none;
      stroke: #d4a0ad;
      stroke-width: 2.8;
      stroke-linecap: round;
      stroke-linejoin: round;
      transition: stroke 0.3s ease;
    }

    /* Phần fill được clip để đổ dần từ dưới lên */
    .heart-fill-clip {
      fill: url(#heartGradient);
      transition: opacity 0.3s ease;
    }

    /* Hiệu ứng glow bên trong */
    .heart-glow {
      opacity: 0;
      transition: opacity 0.5s ease;
    }

    .heart-svg.filled .heart-glow {
      opacity: 0.6;
    }

    .heart-pulse-ring {
      position: absolute;
      inset: -25px;
      border-radius: 50%;
      border: 2px solid rgba(229, 137, 156, 0.15);
      opacity: 0;
      transition: all 0.6s ease;
      pointer-events: none;
    }

    .heart-pulse-ring.active {
      opacity: 1;
      animation: pulseRing 1.2s ease-out forwards;
    }

    @keyframes pulseRing {
      0% {
        transform: scale(0.8);
        opacity: 0.8;
      }

      100% {
        transform: scale(1.8);
        opacity: 0;
      }
    }

    .heart-text {
      font-family: "Dancing Script", cursive;
      font-size: 26px;
      color: var(--plum-soft);
      transition: all 0.4s ease;
      min-height: 44px;
      opacity: 0.85;
      text-align: center;
      line-height: 1.4;
      font-weight: 500;
    }

    .heart-text.filled {
      color: var(--rose-deep);
      opacity: 1;
      animation: textPulse 1s ease-in-out infinite;
    }

    @keyframes textPulse {

      0%,
      100% {
        transform: scale(1);
      }

      50% {
        transform: scale(1.05);
      }
    }

    .heart-progress {
      width: 200px;
      height: 5px;
      background: rgba(229, 137, 156, 0.2);
      border-radius: 10px;
      overflow: hidden;
      opacity: 0;
      transition: opacity 0.5s ease;
    }

    .heart-progress.show {
      opacity: 1;
    }

    .heart-progress-bar {
      height: 100%;
      width: 0%;
      background: linear-gradient(90deg, #ff6b8a, #e5597a, #b23b54);
      border-radius: 10px;
      transition: width 0.08s ease;
    }

    .heart-sparkles {
      position: absolute;
      inset: -60px;
      pointer-events: none;
      opacity: 0;
      transition: opacity 0.6s ease;
    }

    .heart-sparkles.active {
      opacity: 1;
    }

    .sparkle {
      position: absolute;
      border-radius: 50%;
      animation: sparkleFloat 1.5s ease-out forwards;
    }

    @keyframes sparkleFloat {
      0% {
        transform: translate(0, 0) scale(0) rotate(0deg);
        opacity: 1;
      }

      100% {
        transform: translate(var(--tx), var(--ty)) scale(1) rotate(360deg);
        opacity: 0;
      }
    }

    .heart-click-hint {
      font-size: 15px;
      color: var(--plum-soft);
      opacity: 0.5;
      animation: bounce 2s ease-in-out infinite;
      font-weight: 500;
      margin-top: 4px;
      transition: opacity 0.5s ease;
      letter-spacing: 0.5px;
    }

    .heart-click-hint.hidden {
      opacity: 0;
      animation: none;
    }

    /* ============ SCREEN 4 - REVEAL ============ */
    #screen-reveal {
      justify-content: flex-start;
      padding: 0;
      background: linear-gradient(180deg, #fff8f2 0%, #fff0f3 100%);
      /* THÊM: Cho phép scroll */
      overflow-y: auto;
      -webkit-overflow-scrolling: touch;
    }

    #screen-reveal.active {
      display: flex;
    }

    .reveal-wrap {
      max-width: 440px;
      margin: 0 auto;
      padding: 40px 24px 50px;
      width: 100%;
    }

    .reveal-head {
      text-align: center;
      margin-bottom: 20px;
    }

    .reveal-eyebrow {
      display: block;
      font-size: 12px;
      letter-spacing: 0.26em;
      text-transform: uppercase;
      color: var(--rose-deep);
      font-weight: 600;
      margin-bottom: 12px;
    }

    .reveal-names {
      font-family: "Dancing Script", cursive;
      font-weight: 700;
      font-size: 44px;
      color: var(--plum);
      margin: 0;
    }

    .reveal-names .amp {
      color: var(--rose);
      padding: 0 6px;
    }

    .counter-eyebrow {
      display: block;
      font-size: 12px;
      letter-spacing: 0.24em;
      text-transform: uppercase;
      color: var(--rose-deep);
      font-weight: 600;
      margin: 20px 0 12px;
    }

    .day-counter-panel {
      display: inline-flex;
      gap: 10px;
      background: #fff;
      padding: 16px 20px;
      border-radius: 24px;
      box-shadow: var(--shadow-lg);
      flex-wrap: wrap;
      justify-content: center;
      border: 1px solid rgba(229, 137, 156, 0.1);
    }

    .day-card {
      background: linear-gradient(155deg, #f9d5df, #fbe3e8);
      border-radius: 16px;
      padding: 10px 6px 8px;
      min-width: 60px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 4px;
    }

    .day-card .num {
      font-family: "Quicksand", sans-serif;
      font-weight: 700;
      font-size: 24px;
      color: var(--rose-deep);
      line-height: 1;
    }

    .day-card .lab {
      font-family: "Dancing Script", cursive;
      font-weight: 600;
      font-size: 18px;
      color: var(--plum-soft);
      line-height: 1;
    }

    .total-days-badge {
      display: inline-block;
      margin-top: 16px;
      background: linear-gradient(135deg, #e5597a, #c96c82);
      color: #fff;
      padding: 10px 22px;
      border-radius: 30px;
      font-family: "Quicksand", sans-serif;
      font-weight: 700;
      font-size: 15px;
      letter-spacing: 0.04em;
      box-shadow: 0 8px 20px rgba(201, 108, 130, 0.35);
      animation: softGlow 2s ease-in-out infinite alternate;
    }

    @keyframes softGlow {
      from {
        box-shadow: 0 8px 20px rgba(201, 108, 130, 0.35);
      }

      to {
        box-shadow: 0 8px 25px rgba(201, 108, 130, 0.5);
      }
    }

    .total-days-badge .big-number {
      font-size: 26px;
      font-weight: 700;
      margin: 0 4px;
      font-family: "Dancing Script", cursive;
    }

    .heart-divider {
      display: flex;
      justify-content: center;
      margin: 30px 0;
    }

    .heart-divider svg {
      width: 20px;
      height: 20px;
      fill: var(--rose);
      opacity: 0.6;
    }

    .carousel-scene {
      width: 100%;
      height: 320px;
      perspective: 1200px;
      margin: 40px 0 60px;
      position: relative;
      display: flex;
      justify-content: center;
      align-items: center;
    }

    .carousel {
      width: 180px;
      height: 240px;
      position: relative;
      -webkit-transform-style: preserve-3d;
      transform-style: preserve-3d;
      /* Rotate container instead of items to ensure it works on all browsers */
      animation: rotateCarousel 16s infinite linear;
      -webkit-animation: rotateCarousel 16s infinite linear;
    }

    .carousel-item {
      position: absolute;
      width: 100%;
      height: 100%;
      background: #fff;
      border: 6px solid var(--cream);
      box-shadow: 0 15px 35px rgba(74, 46, 56, 0.2);
      border-radius: 12px;
      overflow: hidden;
      display: flex;
      align-items: center;
      justify-content: center;
      -webkit-backface-visibility: visible;
      backface-visibility: visible;
      /* Optional: smooth transition if needed */
    }

    .carousel-item img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }

    /* Đặt vị trí tĩnh cho 4 ảnh thành hình tròn trụ */
    .item-1 { transform: rotateY(0deg) translateZ(180px); -webkit-transform: rotateY(0deg) translateZ(180px); }
    .item-2 { transform: rotateY(90deg) translateZ(180px); -webkit-transform: rotateY(90deg) translateZ(180px); }
    .item-3 { transform: rotateY(180deg) translateZ(180px); -webkit-transform: rotateY(180deg) translateZ(180px); }
    .item-4 { transform: rotateY(270deg) translateZ(180px); -webkit-transform: rotateY(270deg) translateZ(180px); }

    /* Keyframes xoay nguyên cả cụm carousel */
    @keyframes rotateCarousel {
      0% { transform: rotateX(-5deg) rotateY(0deg); }
      100% { transform: rotateX(-5deg) rotateY(360deg); }
    }
    
    @-webkit-keyframes rotateCarousel {
      0% { -webkit-transform: rotateX(-5deg) rotateY(0deg); }
      100% { -webkit-transform: rotateX(-5deg) rotateY(360deg); }
    }

    .photo-slot img {
      width: 100%;
      height: auto;
      object-fit: contain;
      display: block;
      border-radius: 4px;
      background: var(--blush);
    }

    .photo-slot svg {
      width: 30px;
      height: 30px;
      fill: var(--rose);
      opacity: 0.9;
    }

    .photo-slot span {
      font-size: 13px;
      color: var(--rose-deep);
      font-weight: 600;
    }

    .letter-card {
      position: relative;
      background: #fff;
      border-radius: 24px;
      box-shadow: var(--shadow-lg);
      padding: 28px 24px 24px;
      border: 1px solid rgba(229, 137, 156, 0.1);
    }

    .letter-icon {
      width: 34px;
      height: 34px;
      margin: 0 auto 12px;
      opacity: 0.9;
    }

    .letter-icon svg {
      width: 100%;
      height: 100%;
      fill: var(--rose);
    }

    .letter-greeting {
      font-family: "Dancing Script", cursive;
      font-size: 28px;
      color: var(--rose-deep);
      margin: 0 0 14px;
      text-align: center;
    }

    .letter-body {
      font-size: 15px;
      line-height: 1.8;
      color: var(--plum-soft);
      margin: 0;
      white-space: pre-line;
    }

    .letter-sign {
      font-family: "Dancing Script", cursive;
      font-size: 26px;
      color: var(--plum);
      text-align: right;
      margin-top: 18px;
    }

    .reveal-footer {
      text-align: center;
      font-size: 12px;
      color: var(--plum-soft);
      opacity: 0.8;
      margin-top: 32px;
      font-weight: 500;
    }

    /* ================= MEDIA QUERIES ================= */

    @media (max-width: 480px) {
      .screen {
        padding: 16px;
      }

      .gift-icon {
        width: 56px;
        height: 56px;
        margin-bottom: 14px;
      }

      .gift-title {
        font-size: 26px;
      }

      .gift-sub {
        font-size: 13px;
        margin-bottom: 16px;
      }

      .gift-bar {
        width: 100px;
        height: 3px;
      }

      .env-msg {
        font-size: 14px;
        max-width: 240px;
        margin-bottom: 20px;
        line-height: 1.6;
      }

      .envelope-btn {
        min-width: 110px;
        min-height: 110px;
        gap: 12px;
      }

      .envelope-shape {
        width: 110px;
        height: 76px;
      }

      .press-hint {
        font-size: 11px;
      }

      .quiz-container {
        padding: 24px 18px 20px;
      }

      .quiz-title {
        font-size: 24px;
      }

      #quizAnswer {
        padding: 10px 14px;
        font-size: 16px;
        /* Giữ 16px để tránh zoom */
      }

      .quiz-btn {
        padding: 12px;
        font-size: 15px;
      }

      .heart-container {
        width: 170px;
        height: 170px;
      }

      .heart-text {
        font-size: 20px;
        min-height: 36px;
      }

      .heart-progress {
        width: 150px;
        height: 4px;
      }

      .heart-click-hint {
        font-size: 13px;
      }

      .reveal-wrap {
        padding: 20px 14px 32px;
      }

      .reveal-eyebrow {
        font-size: 10px;
        letter-spacing: 0.2em;
        margin-bottom: 8px;
      }

      .reveal-names {
        font-size: 30px;
      }

      .counter-eyebrow {
        font-size: 10px;
        margin: 14px 0 10px;
      }

      .day-counter-panel {
        gap: 6px;
        padding: 10px 12px;
        border-radius: 16px;
      }

      .day-card {
        min-width: 40px;
        padding: 6px 4px 6px;
        border-radius: 10px;
        gap: 2px;
      }

      .day-card .num {
        font-size: 18px;
      }

      .day-card .lab {
        font-size: 14px;
      }

      .total-days-badge {
        font-size: 12px;
        padding: 8px 16px;
      }

      .total-days-badge .big-number {
        font-size: 20px;
      }

      .heart-divider {
        margin: 18px 0;
      }

      .heart-divider svg {
        width: 14px;
        height: 14px;
      }

      .polaroid {
        max-width: 210px;
        padding: 10px 10px 30px;
        border-radius: 10px;
      }

      .polaroid-sticker {
        top: -10px;
        right: -10px;
        width: 28px;
        height: 28px;
      }

      .polaroid-sticker svg {
        width: 14px;
        height: 14px;
      }

      .polaroid-cap {
        font-size: 16px;
        bottom: 10px;
      }

      .photo-slot {
        border-radius: 6px;
      }

      .photo-slot svg {
        width: 20px;
        height: 20px;
      }

      .photo-slot span {
        font-size: 11px;
      }

      .letter-card {
        padding: 18px 14px 16px;
        border-radius: 16px;
      }

      .letter-icon {
        width: 26px;
        height: 26px;
        margin-bottom: 8px;
      }

      .letter-greeting {
        font-size: 22px;
        margin-bottom: 10px;
      }

      .letter-body {
        font-size: 13px;
        line-height: 1.7;
      }

      .letter-sign {
        font-size: 20px;
        margin-top: 12px;
      }

      .reveal-footer {
        font-size: 11px;
        margin-top: 20px;
      }
    }

    @media (max-height: 600px) {
      .heart-container {
        width: 140px;
        height: 140px;
      }

      .heart-text {
        font-size: 18px;
        min-height: 30px;
      }

      .heart-progress {
        width: 130px;
        height: 4px;
      }

      .heart-click-hint {
        font-size: 12px;
      }

      .heart-interactive {
        gap: 16px;
      }
    }

    @media (min-width: 481px) and (max-width: 768px) {
      .screen {
        padding: 24px;
      }

      .heart-container {
        width: 200px;
        height: 200px;
      }

      .reveal-wrap {
        padding: 28px 20px 40px;
      }

      .reveal-names {
        font-size: 36px;
      }

      .polaroid {
        max-width: 240px;
      }
    }

    @media (min-width: 1200px) {
      .reveal-wrap {
        max-width: 500px;
        padding: 50px 32px 60px;
      }

      .polaroid {
        max-width: 320px;
      }

      .letter-body {
        font-size: 16px;
        line-height: 1.9;
      }
    }



    button:focus-visible {
      outline: 2px solid var(--rose-deep);
      outline-offset: 4px;
    }

    /* THÊM: Style cho nút nhạc */
    #musicToggle {
      position: fixed;
      bottom: 20px;
      right: 20px;
      z-index: 999;
      background: var(--rose);
      color: white;
      border: none;
      border-radius: 50%;
      width: 44px;
      height: 44px;
      font-size: 20px;
      cursor: pointer;
      box-shadow: 0 4px 12px rgba(201, 108, 130, 0.4);
      display: none;
      align-items: center;
      justify-content: center;
      transition:
        transform 0.2s,
        background 0.2s;
      touch-action: manipulation;
    }

    #musicToggle:active {
      transform: scale(0.9);
    }

    /* THÊM: Touch Sparkles */
    .touch-sparkle {
      position: fixed;
      pointer-events: none;
      z-index: 9999;
      animation: floatUp 1.2s ease-out forwards;
      font-size: 22px;
      user-select: none;
      filter: drop-shadow(0 2px 4px rgba(229, 137, 156, 0.4));
    }

    @keyframes floatUp {
      0% {
        transform: translate(-50%, -50%) scale(0.5);
        opacity: 1;
      }

      100% {
        transform: translate(-50%, -150%) scale(1.2);
        opacity: 0;
      }
    }