/* ========================================
   GST Calculator — Design System & Styles
   ======================================== */

/* --- CSS Variables (Design Tokens) --- */
:root {
    --bg-dark: #0a0a1a;
    --bg-card: rgba(255, 255, 255, 0.04);
    --bg-card-hover: rgba(255, 255, 255, 0.07);
    --bg-input: rgba(255, 255, 255, 0.06);
    --bg-input-focus: rgba(255, 255, 255, 0.1);
    --border-subtle: rgba(255, 255, 255, 0.08);
    --border-focus: rgba(129, 140, 248, 0.5);

    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;

    --accent: #818cf8;
    --accent-glow: rgba(129, 140, 248, 0.25);
    --accent-2: #a78bfa;
    --success: #34d399;
    --success-glow: rgba(52, 211, 153, 0.2);
    --danger: #f87171;
    --subtract-color: #fb923c;

    --radius-sm: 8px;
    --radius-md: 14px;
    --radius-lg: 20px;
    --radius-xl: 28px;

    --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.4), 0 0 0 1px var(--border-subtle);
    --shadow-input: 0 2px 8px rgba(0, 0, 0, 0.2);

    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* --- Reset & Base --- */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font);
    background: var(--bg-dark);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow-x: hidden;
    padding: 24px 16px;
    position: relative;
}

/* --- Animated Background Blobs --- */
.bg-blobs {
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 0;
    overflow: hidden;
}

.blob {
    position: absolute;
    border-radius: 50%;
    filter: blur(100px);
    opacity: 0.4;
    animation: float 20s ease-in-out infinite;
}

.blob-1 {
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(129, 140, 248, 0.35), transparent 70%);
    top: -10%;
    left: -5%;
    animation-delay: 0s;
}

.blob-2 {
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(167, 139, 250, 0.3), transparent 70%);
    bottom: -15%;
    right: -5%;
    animation-delay: -7s;
}

.blob-3 {
    width: 350px;
    height: 350px;
    background: radial-gradient(circle, rgba(52, 211, 153, 0.2), transparent 70%);
    top: 50%;
    left: 60%;
    animation-delay: -14s;
}

@keyframes float {

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

    25% {
        transform: translate(40px, -30px) scale(1.05);
    }

    50% {
        transform: translate(-20px, 20px) scale(0.95);
    }

    75% {
        transform: translate(30px, 40px) scale(1.02);
    }
}

/* --- Container --- */
.container {
    position: relative;
    z-index: 1;
    width: 100%;
    max-width: 480px;
}

/* --- Navigation Bar --- */
.navbar {
    display: flex;
    justify-content: center;
    gap: 16px;
    margin-bottom: 24px;
    background: var(--bg-card);
    padding: 12px 20px;
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-subtle);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 600;
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.nav-link:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
}

.nav-link.active {
    color: var(--accent);
    background: var(--accent-glow);
}

/* --- Header --- */
.header {
    text-align: center;
    margin-bottom: 32px;
}

.logo-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 56px;
    height: 56px;
    border-radius: 16px;
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    margin-bottom: 16px;
    box-shadow: 0 4px 24px var(--accent-glow);
    animation: pulse-glow 4s ease-in-out infinite;
}

.logo-icon svg {
    width: 28px;
    height: 28px;
    color: #fff;
}

@keyframes pulse-glow {

    0%,
    100% {
        box-shadow: 0 4px 24px var(--accent-glow);
    }

    50% {
        box-shadow: 0 4px 40px rgba(129, 140, 248, 0.45);
    }
}

h1 {
    font-size: 1.85rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 6px;
}

.subtitle {
    font-size: 0.9rem;
    color: var(--text-muted);
    font-weight: 400;
}

/* --- Calculator Card --- */
.calc-card {
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-xl);
    padding: 32px 28px;
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    box-shadow: var(--shadow-card);
    transition: var(--transition);
}

/* --- Steps --- */
.step {
    transition: opacity 0.5s ease, transform 0.5s ease;
}

.step.hidden {
    display: none;
}

.step.fade-in {
    animation: fadeSlideUp 0.5s ease forwards;
}

@keyframes fadeSlideUp {
    from {
        opacity: 0;
        transform: translateY(16px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* --- Step Badge --- */
.step-badge {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--accent);
    background: var(--accent-glow);
    padding: 4px 12px;
    border-radius: 20px;
    margin-bottom: 14px;
}

/* --- Labels --- */
label {
    display: block;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 10px;
}

/* --- Input Group --- */
.input-group {
    position: relative;
    margin-bottom: 6px;
}

.currency {
    position: absolute;
    left: 16px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-muted);
    pointer-events: none;
    transition: color var(--transition);
}

.input-group:focus-within .currency {
    color: var(--accent);
}

input[type="text"] {
    width: 100%;
    padding: 14px 18px 14px 44px;
    font-size: 1.15rem;
    font-weight: 600;
    font-family: var(--font);
    color: var(--text-primary);
    background: var(--bg-input);
    border: 1.5px solid var(--border-subtle);
    border-radius: var(--radius-md);
    outline: none;
    transition: var(--transition);
    box-shadow: var(--shadow-input);
}

input[type="text"]::placeholder {
    color: var(--text-muted);
    font-weight: 400;
}

input[type="text"]:focus {
    background: var(--bg-input-focus);
    border-color: var(--border-focus);
    box-shadow: 0 0 0 4px var(--accent-glow), var(--shadow-input);
}

input[type="text"].input-error {
    border-color: var(--danger);
    box-shadow: 0 0 0 4px rgba(248, 113, 113, 0.15), var(--shadow-input);
}

/* --- Error Message --- */
.error-msg {
    font-size: 0.8rem;
    color: var(--danger);
    min-height: 22px;
    padding: 4px 0;
    transition: var(--transition);
}

/* --- Buttons --- */
.btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    width: 100%;
    padding: 14px 24px;
    font-size: 1rem;
    font-weight: 600;
    font-family: var(--font);
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.btn-primary {
    color: #fff;
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    box-shadow: 0 4px 20px var(--accent-glow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 28px rgba(129, 140, 248, 0.4);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    color: var(--text-secondary);
    background: rgba(255, 255, 255, 0.06);
    border: 1px solid var(--border-subtle);
    margin-top: 16px;
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
}

.btn-icon {
    font-size: 1.15rem;
    transition: transform var(--transition);
}

.btn:hover .btn-icon {
    transform: translateX(3px);
}

/* --- Breakdown Card --- */
.breakdown-card {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 16px 20px;
    margin-bottom: 24px;
}

.breakdown-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 0;
}

.breakdown-row:not(:last-child) {
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.breakdown-row .label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.breakdown-row .label small {
    color: var(--text-muted);
    font-weight: 400;
}

.breakdown-row .value {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-primary);
}

.breakdown-row.highlight .value {
    color: var(--accent);
    font-size: 1.1rem;
}

/* --- Result Card --- */
.result-card {
    background: linear-gradient(135deg, rgba(129, 140, 248, 0.08), rgba(52, 211, 153, 0.06));
    border: 1px solid rgba(129, 140, 248, 0.15);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.result-header {
    padding: 14px 20px;
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--accent);
    background: rgba(129, 140, 248, 0.06);
    border-bottom: 1px solid rgba(129, 140, 248, 0.1);
}

.result-rows {
    padding: 8px 20px;
}

.result-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 0;
    font-size: 0.9rem;
}

.result-row:not(:last-child) {
    border-bottom: 1px solid rgba(255, 255, 255, 0.04);
}

.result-row span:first-child {
    color: var(--text-secondary);
}

.result-row span:last-child {
    font-weight: 600;
    color: var(--text-primary);
}

.result-row .subtract-val {
    color: var(--subtract-color) !important;
}

.result-total {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 20px;
    background: rgba(52, 211, 153, 0.08);
    border-top: 1px solid rgba(52, 211, 153, 0.12);
}

.result-total span:first-child {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-primary);
}

.result-total span:last-child {
    font-size: 1.35rem;
    font-weight: 800;
    color: var(--success);
    text-shadow: 0 0 20px var(--success-glow);
}

/* --- Footer --- */
.footer {
    text-align: center;
    margin-top: 24px;
    font-size: 0.75rem;
    color: var(--text-muted);
}

.footer strong {
    color: var(--text-secondary);
}

/* --- Responsive --- */
@media (max-width: 520px) {
    .calc-card {
        padding: 24px 18px;
        border-radius: var(--radius-lg);
    }

    h1 {
        font-size: 1.5rem;
    }

    .logo-icon {
        width: 48px;
        height: 48px;
    }

    .logo-icon svg {
        width: 24px;
        height: 24px;
    }

    input[type="text"] {
        font-size: 1rem;
        padding: 12px 16px 12px 40px;
    }

    .result-total span:last-child {
        font-size: 1.15rem;
    }
}