:root {
    /* Colors - Dark theme with purple/indigo accents */
    --bg-primary: #06060f;
    --bg-secondary: #0c0c1e;
    --bg-card: rgba(15, 15, 40, 0.7);
    --bg-card-hover: rgba(20, 20, 50, 0.8);
    --bg-input: rgba(15, 15, 40, 0.6);
    --bg-glass: rgba(15, 15, 40, 0.4);

    --border-color: rgba(99, 102, 241, 0.15);
    --border-hover: rgba(99, 102, 241, 0.3);
    --border-focus: rgba(139, 92, 246, 0.5);

    --text-primary: #e8e8f0;
    --text-secondary: #8888aa;
    --text-muted: #555577;
    --text-accent: #a78bfa;

    --accent-1: #6366f1;
    --accent-2: #8b5cf6;
    --accent-3: #a855f7;
    --accent-gradient: linear-gradient(135deg, #6366f1, #8b5cf6, #a855f7);
    --accent-glow: rgba(99, 102, 241, 0.15);

    --success: #34d399;
    --warning: #fbbf24;
    --danger: #f87171;
    --info: #60a5fa;

    /* Typography */
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

    /* Spacing */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;

    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 30px rgba(99, 102, 241, 0.15);

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.25s ease;
    --transition-slow: 0.4s ease;
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-main);
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
    overflow-x: hidden;
}

/* Background animated gradient */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background:
        radial-gradient(ellipse 80% 60% at 20% 10%, rgba(99, 102, 241, 0.08), transparent),
        radial-gradient(ellipse 60% 50% at 80% 90%, rgba(139, 92, 246, 0.06), transparent),
        radial-gradient(ellipse 50% 40% at 50% 50%, rgba(168, 85, 247, 0.04), transparent);
    pointer-events: none;
    z-index: 0;
    animation: bgPulse 8s ease-in-out infinite alternate;
}

@keyframes bgPulse {
    0% { opacity: 0.7; }
    100% { opacity: 1; }
}

/* ===== LAYOUT ===== */
.page-wrapper {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 2rem 1.5rem;
}

/* ===== HERO SECTION ===== */
.hero {
    text-align: center;
    margin-bottom: 2.5rem;
    animation: fadeInUp 0.6s ease-out;
}

.hero .logo {
    font-size: 2.5rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    margin-bottom: 0.5rem;
}

.hero .logo span {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero .tagline {
    font-size: 1.1rem;
    color: var(--text-secondary);
    font-weight: 400;
    max-width: 400px;
    margin: 0 auto;
}

/* ===== CARD / FORM ===== */
.shortener-card {
    width: 100%;
    max-width: 520px;
    background: var(--bg-card);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: 2rem;
    box-shadow: var(--shadow-lg), var(--shadow-glow);
    animation: fadeInUp 0.7s ease-out 0.1s backwards;
}

.input-group {
    margin-bottom: 1.25rem;
}

.input-group label {
    display: block;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 0.5rem;
}

.url-input-wrapper {
    position: relative;
}

.url-input-wrapper .icon {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    font-size: 1rem;
    pointer-events: none;
}

input[type="url"],
input[type="text"],
input[type="number"] {
    width: 100%;
    padding: 0.85rem 1rem 0.85rem 2.75rem;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: var(--font-main);
    font-size: 0.95rem;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
    outline: none;
}

input[type="number"] {
    padding-left: 1rem;
}

input:focus {
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

input::placeholder {
    color: var(--text-muted);
}

/* CAPTCHA */
.captcha-section {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1.25rem;
}

.captcha-image {
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
    height: 48px;
    flex-shrink: 0;
    cursor: pointer;
    transition: opacity var(--transition-fast);
}

.captcha-image:hover {
    opacity: 0.8;
}

.captcha-input {
    flex: 1;
}

.captcha-input input {
    padding-left: 1rem !important;
}

.captcha-refresh {
    background: none;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-fast);
    flex-shrink: 0;
    font-size: 1.2rem;
}

.captcha-refresh:hover {
    border-color: var(--border-hover);
    color: var(--text-accent);
    background: var(--bg-card-hover);
}

/* Button */
.btn-shorten {
    width: 100%;
    padding: 0.9rem 1.5rem;
    background: var(--accent-gradient);
    color: #fff;
    border: none;
    border-radius: var(--radius-md);
    font-family: var(--font-main);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.btn-shorten::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.1), transparent);
    transition: left 0.5s ease;
}

.btn-shorten:hover::before {
    left: 100%;
}

.btn-shorten:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(99, 102, 241, 0.3);
}

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

.btn-shorten:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

.btn-shorten .spinner {
    display: none;
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255,255,255,0.3);
    border-top-color: #fff;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
    margin: 0 auto;
}

.btn-shorten.loading .spinner {
    display: inline-block;
}

.btn-shorten.loading .btn-text {
    display: none;
}

/* Result */
.result-section {
    margin-top: 1.5rem;
    padding: 1.25rem;
    background: rgba(52, 211, 153, 0.05);
    border: 1px solid rgba(52, 211, 153, 0.2);
    border-radius: var(--radius-md);
    display: none;
    animation: fadeInUp 0.4s ease-out;
}

.result-section.visible {
    display: block;
}

.result-label {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--success);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 0.5rem;
}

.result-link-wrapper {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.result-link {
    flex: 1;
    font-family: var(--font-mono);
    font-size: 0.95rem;
    color: var(--text-accent);
    word-break: break-all;
    padding: 0.6rem 0.75rem;
    background: var(--bg-input);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
}

.btn-copy {
    padding: 0.6rem 1rem;
    background: rgba(52, 211, 153, 0.15);
    color: var(--success);
    border: 1px solid rgba(52, 211, 153, 0.3);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-family: var(--font-main);
    font-weight: 600;
    font-size: 0.8rem;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.btn-copy:hover {
    background: rgba(52, 211, 153, 0.25);
}

.btn-copy.copied {
    background: rgba(52, 211, 153, 0.3);
    color: #fff;
}

/* Error */
.error-message {
    margin-top: 1rem;
    padding: 0.75rem 1rem;
    background: rgba(248, 113, 113, 0.08);
    border: 1px solid rgba(248, 113, 113, 0.2);
    border-radius: var(--radius-sm);
    color: var(--danger);
    font-size: 0.85rem;
    display: none;
    animation: shake 0.4s ease;
}

.error-message.visible {
    display: block;
}

/* ===== FOOTER ===== */
.footer {
    margin-top: 3rem;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.8rem;
    animation: fadeInUp 0.8s ease-out 0.2s backwards;
}

.footer a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.footer a:hover {
    color: var(--text-accent);
}

/* ===== ANIMATIONS ===== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    20% { transform: translateX(-6px); }
    40% { transform: translateX(6px); }
    60% { transform: translateX(-4px); }
    80% { transform: translateX(4px); }
}

/* ===== RESPONSIVE ===== */
@media (max-width: 600px) {
    .hero .logo {
        font-size: 2rem;
    }

    .hero .tagline {
        font-size: 0.95rem;
    }

    .shortener-card {
        padding: 1.5rem;
    }

    .captcha-section {
        flex-wrap: wrap;
    }

    .captcha-image {
        width: 100%;
        height: auto;
        object-fit: contain;
    }
}

/* ===== PARTICLES (optional decorative) ===== */
.particle {
    position: fixed;
    width: 3px;
    height: 3px;
    background: var(--accent-2);
    border-radius: 50%;
    opacity: 0.15;
    pointer-events: none;
    animation: float 15s infinite;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0) translateX(0);
        opacity: 0;
    }
    10% { opacity: 0.15; }
    90% { opacity: 0.15; }
    50% {
        transform: translateY(-100vh) translateX(50px);
    }
}