/* Biến nội bộ */
.doppler-neo-wrapper {
    --bg-white: #ffffff;
    --border-ink: 3px solid #111111;
    --shadow-solid: 5px 5px 0px #111111;
    --shadow-push: 2px 2px 0px #111111;
    
    /* Bảng màu Doppler */
    --clr-sky: #4361ee;      /* Xanh lam */
    --clr-high: #f72585;     /* Đỏ hồng - Âm cao */
    --clr-low: #4cc9f0;      /* Xanh nhạt - Âm thấp */
    --clr-bg: #f8f9fa;
    --clr-highlight: #e0fbfc;

    max-width: 850px;
    margin: 0 auto;
    font-family: system-ui, -apple-system, sans-serif;
    color: #111111;
    background: var(--clr-bg);
    padding: 20px;
    border: var(--border-ink);
    border-radius: 16px;
    box-shadow: 8px 8px 0px #111;
}

.doppler-neo-wrapper * { box-sizing: border-box; }

/* Header */
.doppler-neo-header { background: var(--clr-sky); color: #fff; border: var(--border-ink); box-shadow: var(--shadow-solid); padding: 20px; border-radius: 12px; text-align: center; margin-bottom: 25px; }
.doppler-neo-header h2 { margin: 0 0 10px 0; font-size: 1.8rem; font-weight: 900; text-transform: uppercase; color: #fff;}
.doppler-neo-header p { margin: 0; font-weight: 800; font-size: 0.95rem; }

/* Form Styles */
.doppler-neo-form { display: flex; flex-direction: column; gap: 20px; }
.doppler-form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.doppler-group { display: flex; flex-direction: column; gap: 10px; }
.doppler-group label { font-weight: 900; font-size: 1.05rem; color: #111; }

.doppler-card-input { background: #fff; border: 2px dashed #111; border-radius: 12px; padding: 20px; display: flex; flex-direction: column; gap: 15px;}
.doppler-card-input h3 { margin: 0; font-size: 1.2rem; font-weight: 900; color: #111; border-bottom: 2px solid #111; padding-bottom: 8px; text-transform: uppercase;}

/* CSS FIX CHUẨN Ô INPUT & SELECT (Chống méo) */
.input-with-select { 
    display: flex; flex-wrap: nowrap; align-items: stretch; border: var(--border-ink); border-radius: 12px; box-shadow: 4px 4px 0px #111; background: #fff; overflow: hidden; width: 100%;
}
.input-with-select input { 
    border: none !important; border-radius: 0 !important; box-shadow: none !important; flex: 1; width: 100%; min-width: 50%; padding: 16px 15px !important; font-size: 1.3rem !important; font-weight: 900; color: #111; outline: none;
}
.input-with-select select { 
    border: none; border-left: 3px solid #111; padding: 0 15px; font-weight: 900; font-size: 1.1rem; background: #e9ecef; outline: none; cursor: pointer; color: #111; flex: 0 0 auto; width: 90px; text-align: center;
}
.input-with-select select:disabled { opacity: 1; color: #111; background: #e9ecef;}
.input-with-select input:focus { background: var(--clr-highlight); }

/* Quick Tags & Radios */
.input-with-quick { display: flex; flex-direction: column; gap: 10px; }
.quick-tags { display: flex; gap: 8px; flex-wrap: wrap; }
.q-tag { padding: 4px 12px; border: 2px solid #111; border-radius: 20px; font-size: 0.85rem; font-weight: 800; cursor: pointer; background: #fff; box-shadow: 2px 2px 0px #111; color: #111; transition: transform 0.1s;}
.q-tag:hover { background: #e9ecef; }
.q-tag:active { box-shadow: 0px 0px 0px #111; transform: translate(2px,2px); }

.doppler-radio-group { display: flex; gap: 10px; }
.doppler-radio-group .radio-neo { flex: 1; cursor: pointer; }
.doppler-radio-group input { display: none; }
.doppler-radio-group .neo-content { display: flex; align-items: center; justify-content: center; text-align: center; padding: 10px; font-weight: 800; border: var(--border-ink); border-radius: 8px; background: var(--bg-white); box-shadow: 3px 3px 0px #111; transition: all 0.15s; font-size: 0.95rem; color: #111;}
.doppler-radio-group input:checked + .neo-content { background: var(--clr-sky); color: #fff; box-shadow: var(--shadow-push); transform: translate(2px, 2px); }
.doppler-radio-group input[value="stop"]:checked + .neo-content { background: #333; }

.doppler-error-alert { background: #d00000; color: #fff; border: var(--border-ink); padding: 12px; border-radius: 8px; font-weight: 800; text-align: center; }

/* Button */
.doppler-neo-btn { padding: 18px; font-size: 1.2rem; font-weight: 900; background: #111; color: #fff; border: var(--border-ink); border-radius: 12px; box-shadow: 5px 5px 0px var(--clr-sky); cursor: pointer; text-transform: uppercase; transition: all 0.1s; margin-top: 5px; letter-spacing: 1px;}
.doppler-neo-btn:active { box-shadow: 2px 2px 0px var(--clr-sky); transform: translate(3px, 3px); }

/* Result Layout */
.doppler-neo-result { margin-top: 30px; padding-top: 25px; border-top: 4px dashed #111; display: flex; flex-direction: column; gap: 20px;}
.doppler-neo-result.active { display: flex !important; animation: dopAnim 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards; }

.doppler-result-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 15px; }
.doppler-card { border: var(--border-ink); box-shadow: var(--shadow-solid); border-radius: 12px; padding: 25px 15px; text-align: center; display: flex; flex-direction: column; justify-content: center; align-items: center;}
.card-main { background: var(--clr-high); color: #fff; }
.card-main h4, .card-main .val-text { color: #fff; }
.card-sub { background: #fff; }

.doppler-card h4 { margin: 0 0 10px 0; font-size: 1.1rem; color: #111; font-weight: 900; text-transform: uppercase;}
.val-text { font-size: 3rem; font-weight: 900; color: #111; line-height: 1; margin-bottom: 10px;}
.val-text small { font-size: 1.2rem; font-weight: 900; margin-left: 2px;}
.val-desc { margin: 0; font-size: 1rem; font-weight: 800; color: #444; }

.text-dynamic.text-up { color: #d00000; }
.text-dynamic.text-down { color: #0077b6; }
.text-dynamic.text-equal { color: #111; }

.tag-status { font-size: 1rem; font-weight: 900; background: #111; color: #fff; padding: 6px 15px; border-radius: 8px;}

/* Hướng dẫn giải Step-by-step */
.doppler-solution-box { background: #fff; border: var(--border-ink); border-radius: 12px; padding: 20px; box-shadow: var(--shadow-solid);}
.doppler-solution-box h3 { margin: 0 0 15px 0; font-size: 1.2rem; font-weight: 900; text-transform: uppercase; border-bottom: 3px solid #111; padding-bottom: 10px;}
.step-box { margin-bottom: 15px; padding-bottom: 15px; border-bottom: 2px dashed #ccc; }
.step-box:last-child { margin-bottom: 0; padding-bottom: 0; border-bottom: none;}
.step-box strong { font-size: 1.05rem; color: #111; font-weight: 900;}
.step-box p { font-size: 1rem; font-weight: 700; color: #333; margin: 8px 0 0 0; line-height: 1.5; }
.math-line { font-family: monospace, system-ui; font-size: 1.15rem !important; font-weight: 900 !important; color: #d00000 !important; background: #f8f9fa; padding: 12px; border-radius: 8px; border: 1px solid #ccc; overflow-x: auto;}

/* CANVAS ĐỒ THỊ */
.doppler-canvas-box { background: #fff; border: var(--border-ink); border-radius: 12px; padding: 20px; box-shadow: var(--shadow-solid); text-align: center;}
.doppler-canvas-box h3 { margin: 0 0 15px 0; font-size: 1.2rem; font-weight: 900; text-transform: uppercase;}
#dopplerCanvas { width: 100%; max-width: 100%; height: auto; border: 2px solid #111; border-radius: 8px; background: #111;} /* Nền đen để sóng nổi bật */

.canvas-legend { display: flex; justify-content: center; gap: 20px; margin-top: 15px; flex-wrap: wrap;}
.lg-item { display: flex; align-items: center; gap: 8px; font-weight: 800; font-size: 0.95rem; color: #111;}
.lg-color { width: 15px; height: 15px; border: 2px solid #111; border-radius: 3px; }
.bg-source { background: #f72585; }
.bg-obs { background: #4cc9f0; }
.bg-wave { background: rgba(255, 255, 255, 0.5); }

@keyframes dopAnim { 0% { opacity: 0; transform: translateY(20px); } 100% { opacity: 1; transform: translateY(0); } }

@media (max-width: 700px) {
    .doppler-form-grid, .doppler-radio-group { flex-direction: column; }
    .doppler-result-grid { grid-template-columns: 1fr; }
}