/* ===================================
   CSS RESET AND BASE STYLES
   =================================== */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.hidden {
    display: none !important;
}

/* ===================================
   CSS CUSTOM PROPERTIES (VARIABLES)
   =================================== */

:root {
    /* Colors */
    --color-primary: #a78bfa;
    --color-primary-dark: #7c3aed;
    --color-secondary: #22d3ee;
    --color-secondary-dark: #0ea5e9;
    --color-success: #34d399;
    --color-error: #fb7185;
    --color-text: #e2e8f0;
    --color-text-light: #94a3b8;
    --color-background: #020617;
    --color-background-alt: #0f172a;
    --color-panel: #111827;
    --color-panel-alt: #1f2937;
    --color-border: rgba(148, 163, 184, 0.35);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-size-base: 16px;
    --font-size-lg: 1.25rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

/* ===================================
   GLOBAL STYLES
   =================================== */

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text);
    background: radial-gradient(circle at top, #1f1b4b 0%, #020617 55%);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ===================================
   HEADER
   =================================== */

header {
    background: linear-gradient(135deg, rgba(15, 23, 42, 0.8), rgba(30, 27, 75, 0.65));
    padding: var(--spacing-md) var(--spacing-md) var(--spacing-xs);
    text-align: center;
    border-bottom: 1px solid rgba(148, 163, 184, 0.2);
    backdrop-filter: blur(10px);
}

header h1 {
    font-size: clamp(1.7rem, 5vw, 2.6rem);
    color: #f8fafc;
    margin-bottom: 0.35rem;
    letter-spacing: -0.01em;
}

.subtitle {
    color: var(--color-text-light);
    font-size: 0.95rem;
    max-width: 42ch;
    margin: 0 auto var(--spacing-sm);
    line-height: 1.4;
    text-align: center;
}

.subtitle.intro {
    margin-top: calc(var(--spacing-xs) * -0.2);
    margin-bottom: var(--spacing-sm);
}

/* ===================================
   MAIN CONTENT
   =================================== */

main {
    flex: 1;
    width: min(960px, 100%);
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    align-items: stretch;
    padding: var(--spacing-md) var(--spacing-md) calc(var(--spacing-xl) + env(safe-area-inset-bottom, 0px));
}

.calculator-container {
    background: linear-gradient(165deg, rgba(17, 24, 39, 0.9), rgba(2, 6, 23, 0.85));
    padding: var(--spacing-lg);
    border-radius: 1.25rem;
    box-shadow: 0 30px 60px rgba(2, 6, 23, 0.6);
    width: 100%;
    border: 1px solid rgba(99, 102, 241, 0.2);
    backdrop-filter: blur(12px);
}

.how-to {
    background: linear-gradient(160deg, rgba(15, 23, 42, 0.9), rgba(2, 6, 23, 0.85));
    border-radius: 1rem;
    box-shadow: 0 20px 40px rgba(2, 6, 23, 0.7);
    padding: var(--spacing-lg);
    border: 1px solid rgba(148, 163, 184, 0.2);
}

.how-to h2 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-sm);
    color: var(--color-secondary);
}

.how-to ol {
    margin-left: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
    line-height: 1.5;
}

.how-to li {
    margin-bottom: var(--spacing-xs);
}

.how-to p {
    color: var(--color-text-light);
}

.usp-strip {
    display: flex;
    gap: 0.35rem;
    justify-content: flex-start;
    padding: 0.35rem var(--spacing-sm) calc(var(--spacing-md) + env(safe-area-inset-bottom, 0px));
    background-color: transparent;
    overflow-x: auto;
    border-bottom: 1px solid rgba(148, 163, 184, 0.12);
    scroll-padding-left: var(--spacing-sm);
}

.usp-strip p {
    font-size: 0.8rem;
    color: var(--color-text);
    font-weight: 600;
    padding: 0.2rem 0.65rem;
    border-radius: 999px;
    background-color: rgba(124, 58, 237, 0.15);
    border: 1px solid rgba(124, 58, 237, 0.3);
    white-space: nowrap;
}

.calculator-header {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-lg);
}

.calculator-header p {
    color: var(--color-text-light);
    font-size: 0.95rem;
}


/* ===================================
   INPUT FIELDS
   =================================== */

.input-group {
    margin-bottom: var(--spacing-lg);
}

.input-grid {
    display: grid;
    gap: var(--spacing-md);
}

label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
    color: var(--color-text);
    font-size: var(--font-size-base);
}

input[type="number"] {
    width: 100%;
    padding: 0.85rem 1.1rem;
    font-size: 1.05rem;
    border: 1px solid rgba(148, 163, 184, 0.4);
    border-radius: var(--radius-sm);
    transition: border-color 0.2s, box-shadow 0.2s;
    background-color: var(--color-panel);
    color: var(--color-text);
    min-height: 44px; /* Touch target minimum */
    appearance: textfield;
    -moz-appearance: textfield; /* Remove spinners in Firefox */
}

/* Hide WebKit spin buttons so inputs stay clean on mobile */
input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

input[type="number"]:focus {
    outline: none;
    border-color: var(--color-secondary);
    box-shadow: 0 0 0 3px rgba(34, 211, 238, 0.15);
}

input[type="number"]:hover {
    border-color: var(--color-secondary);
}

input[type="number"].error {
    border-color: var(--color-error);
}

input[type="number"].valid {
    border-color: var(--color-success);
}

/* ===================================
   VALIDATION ERRORS
   =================================== */

.error-message {
    display: none;
    color: var(--color-error);
    font-size: 0.875rem;
    margin-top: var(--spacing-xs);
}

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

/* ===================================
   RESULT DISPLAY
   =================================== */


.result-display {
    background: var(--color-panel-alt);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    text-align: center;
    margin-bottom: var(--spacing-lg);
    min-height: 120px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    border: 1px solid rgba(148, 163, 184, 0.25);
}

.result-display.has-result {
    border-color: var(--color-success);
    background: rgba(52, 211, 153, 0.08);
}

.result-display .result-label {
    font-size: var(--font-size-lg);
    color: var(--color-text-light);
    margin-bottom: var(--spacing-xs);
}

.result-display .result-value {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-secondary);
}

/* ===================================
   BUTTONS
   =================================== */

.button-group {
    display: flex;
    gap: var(--spacing-sm);
}

button {
    flex: 1;
    padding: 0.85rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: background 0.2s, transform 0.1s;
    min-height: 44px; /* Touch target minimum */
    min-width: 44px;
}

#clear-btn {
    background: linear-gradient(120deg, var(--color-secondary), var(--color-primary));
    color: #020617;
    box-shadow: 0 20px 30px rgba(2, 6, 23, 0.65);
}

#clear-btn:hover {
    background: linear-gradient(120deg, var(--color-secondary-dark), var(--color-primary-dark));
}

#clear-btn:focus {
    outline: 2px solid var(--color-secondary);
    outline-offset: 2px;
}

#clear-btn:active {
    transform: scale(0.98);
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* ===================================
   COOKIE CONSENT TOGGLE
   =================================== */

.cookie-toggle {
    position: fixed;
    bottom: calc(var(--spacing-md) + env(safe-area-inset-bottom, 0px));
    right: var(--spacing-md);
    width: 48px;
    height: 48px;
    border-radius: 50%;
    border: none;
    background-color: var(--color-panel-alt);
    color: var(--color-text);
    font-size: 1.25rem;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
    cursor: pointer;
    z-index: 1001;
}

.cookie-toggle:hover {
    background-color: var(--color-primary-dark);
}

.cookie-toggle:focus {
    outline: 2px solid var(--color-primary-dark);
    outline-offset: 2px;
}

/* ===================================
   ANALYTICS CONSENT BANNER
   =================================== */

.analytics-banner {
    position: fixed;
    bottom: calc(var(--spacing-md) + env(safe-area-inset-bottom, 0px));
    left: 50%;
    transform: translateX(-50%);
    width: min(600px, calc(100% - 2 * var(--spacing-md)));
    background-color: var(--color-panel);
    border: 1px solid rgba(148, 163, 184, 0.25);
    border-radius: var(--radius-md);
    box-shadow: 0 20px 45px rgba(2, 6, 23, 0.7);
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    z-index: 1000;
}

.analytics-banner.hidden {
    display: none;
}

.analytics-banner p {
    font-size: 0.95rem;
    color: var(--color-text);
}

.analytics-banner__actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.analytics-banner__actions button {
    flex: 1;
}

.analytics-banner__actions #analytics-accept {
    background: linear-gradient(120deg, var(--color-secondary), var(--color-primary));
    color: #020617;
}

.analytics-banner__actions #analytics-accept:hover {
    background: linear-gradient(120deg, var(--color-secondary-dark), var(--color-primary-dark));
}

.analytics-banner__actions .ghost {
    background-color: transparent;
    color: var(--color-text);
    border: 1px solid rgba(148, 163, 184, 0.35);
}

.analytics-banner__actions .ghost:hover {
    background-color: rgba(148, 163, 184, 0.1);
}

/* ===================================
   FOOTER
   =================================== */

footer {
    background-color: rgba(2, 6, 23, 0.9);
    padding: var(--spacing-md);
    text-align: center;
    border-top: 1px solid rgba(148, 163, 184, 0.2);
    color: var(--color-text-light);
    font-size: 0.875rem;
}

/* ===================================
   RESPONSIVE DESIGN - MOBILE FIRST
   =================================== */

/* Mobile (<640px) - Base styles above are mobile-first */
@media (max-width: 639px) {
    header {
        padding: var(--spacing-sm) var(--spacing-sm) 0.35rem;
    }

    .subtitle {
        font-size: 0.9rem;
    }

    main {
        padding: var(--spacing-sm) var(--spacing-sm) calc(var(--spacing-lg) + env(safe-area-inset-bottom, 0px));
    }

    .calculator-container {
        padding: var(--spacing-sm) var(--spacing-md);
        border-radius: 0.9rem;
    }

    .calculator-header {
        margin-bottom: var(--spacing-sm);
    }

    .calculator-header p {
        font-size: 0.85rem;
        line-height: 1.3;
    }

    .input-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
        gap: var(--spacing-sm);
        margin-bottom: var(--spacing-sm);
    }

    .input-group {
        margin-bottom: 0;
    }

    .input-group label {
        font-size: 0.85rem;
    }

    input[type="number"] {
        padding: 0.65rem 0.9rem;
        font-size: 0.9rem;
    }

    .result-display {
        padding: var(--spacing-sm) var(--spacing-md);
        min-height: 78px;
        margin-bottom: var(--spacing-sm);
    }

    .result-display .result-label {
        font-size: 0.85rem;
    }

    .result-display .result-value {
        font-size: 1.35rem;
    }

    .button-group {
        flex-direction: column;
        gap: var(--spacing-xs);
        margin-top: var(--spacing-xs);
    }
    
    button {
        width: 100%;
        padding: 0.75rem 1rem;
    }
}


/* Tablet (640px - 1024px) */
@media (min-width: 640px) {
    .calculator-container {
        padding: var(--spacing-xl) 3rem;
    }
    
    header h1 {
        font-size: 2.3rem;
    }
}

/* Desktop (>1024px) */
@media (min-width: 768px) {
    main {
        display: grid;
        grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    }

    .calculator-container {
        padding: var(--spacing-xl);
    }

    .usp-strip {
        grid-column: 1 / -1;
        justify-content: center;
        padding-left: var(--spacing-md);
        padding-right: var(--spacing-md);
    }
}

/* ===================================
   ACCESSIBILITY
   =================================== */

/* Focus indicators for keyboard navigation */
*:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --color-border: #000000;
        --color-text: #000000;
    }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}