:root {
    --grade-a: #10b981; /* Xanh lá */
    --grade-b: #3b82f6; /* Xanh dương */
    --grade-c: #f59e0b; /* Vàng cam */
    --grade-d: #ef4444; /* Đỏ */
    --comp-border: #e2e8f0;
    --comp-bg: #f8fafc;
    --comp-text: #1e293b;
}

#kth-comp-app {
    font-family: 'Segoe UI', system-ui, sans-serif;
    max-width: 900px;
    margin: 40px auto;
}

[v-cloak] { display: none; }

.comp-card {
    background: #fff;
    border-radius: 16px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.08);
    overflow: hidden;
    border: 1px solid var(--comp-border);
}

.comp-header {
    background: #1e293b;
    color: white;
    padding: 30px 20px;
    text-align: center;
}
.tool-tag {
    background: rgba(255,255,255,0.15);
    color: #e2e8f0;
    padding: 5px 12px;
    border-radius: 20px;
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
}
.comp-header h2 { margin: 15px 0 5px; font-size: 28px; color: white; }
.comp-header p { margin: 0; font-size: 15px; color: #cbd5e1; }

/* TABS CHUYỂN ĐỔI */
.comp-tabs {
    display: flex;
    background: #f1f5f9;
    border-bottom: 1px solid var(--comp-border);
}
.tab-btn {
    flex: 1;
    padding: 15px;
    border: none;
    background: transparent;
    cursor: pointer;
    font-weight: 600;
    color: #64748b;
    font-size: 15px;
    transition: all 0.2s;
    border-bottom: 3px solid transparent;
}
.tab-btn:hover { background: #e2e8f0; color: #334155; }
.tab-btn.active {
    background: #fff;
    color: #0f172a;
    border-bottom-color: #3b82f6;
}

.comp-body { padding: 40px; }

/* INPUTS */
.comp-inputs {
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 30px;
}
.input-group { flex: 1; }
.input-group label {
    display: block;
    font-weight: 700;
    margin-bottom: 8px;
    font-size: 13px;
    color: #475569;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.custom-select {
    width: 100%;
    height: 50px;
    padding: 10px 40px 10px 15px;
    border: 2px solid var(--comp-border);
    border-radius: 8px;
    font-size: 16px;
    color: var(--comp-text);
    background-color: #fff;
    cursor: pointer;
    outline: none;
    appearance: none;
    background-image: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%2364748B%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E");
    background-repeat: no-repeat;
    background-position: right 15px center;
    background-size: 12px auto;
}
.custom-select:focus { border-color: #3b82f6; box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.1); }

.exchange-icon { font-size: 20px; color: #94a3b8; padding-top: 25px; flex-shrink: 0; }

/* ACTIONS */
.comp-actions { display: flex; gap: 15px; margin-bottom: 30px; }
.btn-check {
    flex: 2;
    background: #0ea5e9;
    color: white;
    border: none;
    padding: 16px;
    border-radius: 8px;
    font-weight: 700;
    cursor: pointer;
    font-size: 15px;
    transition: 0.2s;
    text-transform: uppercase;
}
.btn-check:hover { background: #0284c7; transform: translateY(-2px); }
.btn-check:disabled { background: #cbd5e1; cursor: not-allowed; transform: none; }

.btn-reset {
    flex: 1;
    background: #fff;
    border: 2px solid var(--comp-border);
    color: #64748b;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
}
.btn-reset:hover { border-color: #94a3b8; }

/* RESULT BOX */
.comp-result {
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid transparent;
    animation: slideIn 0.4s ease;
}

.result-header-box {
    display: flex;
    align-items: center;
    padding: 20px;
    color: white;
}

.result-grade {
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 32px;
    font-weight: 800;
    background: rgba(255,255,255,0.2);
    border-radius: 10px;
    margin-right: 20px;
}

.result-title h3 { margin: 0; font-size: 20px; font-weight: 700; text-transform: uppercase; }
.result-subtitle { font-size: 14px; opacity: 0.9; }

.result-desc { padding: 25px; background: #fff; font-size: 16px; line-height: 1.6; }

/* Color Themes */
.comp-result.grade-a { border-color: var(--grade-a); }
.comp-result.grade-a .result-header-box { background: var(--grade-a); }

.comp-result.grade-b { border-color: var(--grade-b); }
.comp-result.grade-b .result-header-box { background: var(--grade-b); }

.comp-result.grade-c { border-color: var(--grade-c); }
.comp-result.grade-c .result-header-box { background: var(--grade-c); }

.comp-result.grade-d { border-color: var(--grade-d); }
.comp-result.grade-d .result-header-box { background: var(--grade-d); }

/* Legend */
.legend-box {
    padding: 15px 25px;
    background: #f8fafc;
    border-top: 1px solid #e2e8f0;
}
.legend-grid { display: flex; gap: 10px; margin-top: 5px; flex-wrap: wrap; }
.badge { font-size: 11px; padding: 2px 8px; border-radius: 4px; color: white; font-weight: 600; }
.badge.A { background: var(--grade-a); }
.badge.B { background: var(--grade-b); }
.badge.C { background: var(--grade-c); }
.badge.D { background: var(--grade-d); }

.comp-disclaimer { margin-top: 20px; text-align: center; color: #94a3b8; font-size: 13px; font-style: italic; }

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

@media (max-width: 600px) {
    .comp-inputs { flex-direction: column; align-items: stretch; gap: 10px; }
    .exchange-icon { text-align: center; transform: rotate(90deg); padding: 5px 0; }
    .comp-tabs { flex-direction: column; }
    .tab-btn { border-bottom: 1px solid #e2e8f0; border-left: 4px solid transparent; text-align: left; }
    .tab-btn.active { border-bottom-color: #e2e8f0; border-left-color: #3b82f6; }
}