/* CSS Variables */
:root {
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --primary-light: #dbeafe;
    --secondary-color: #6366f1;
    --success-color: #10b981;
    --error-color: #ef4444;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --border-color: #e5e7eb;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --transition: all 0.2s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

/* Container */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem 1rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 2.5rem;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.5rem;
}

header .subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Main */
main {
    flex: 1;
}

/* Section */
.converter-section {
    margin-bottom: 2rem;
}

.converter-section h2 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
    padding-left: 0.5rem;
    border-left: 3px solid var(--primary-color);
}

/* Card */
.converter-card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

/* Input Groups */
.input-group,
.select-group,
.output-group {
    margin-bottom: 1rem;
}

.input-group label,
.select-group label,
.output-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

input[type="text"],
textarea,
select {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: 1rem;
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background-color: var(--card-bg);
    color: var(--text-primary);
    transition: var(--transition);
}

input[type="text"]:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--primary-light);
}

textarea {
    resize: vertical;
    min-height: 80px;
}

textarea[readonly] {
    background-color: var(--bg-color);
    cursor: default;
}

select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24'%3E%3Cpath fill='%236b7280' d='M7 10l5 5 5-5z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.5rem center;
    padding-right: 2.5rem;
}

/* Select Row */
.select-row {
    display: flex;
    gap: 1rem;
    align-items: flex-end;
    margin-bottom: 1rem;
}

.select-row .select-group {
    flex: 1;
    margin-bottom: 0;
}

/* Swap Button */
.swap-btn {
    flex-shrink: 0;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-color);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
}

.swap-btn:hover {
    background: var(--primary-light);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

/* Convert Button */
.convert-btn {
    width: 100%;
    padding: 0.875rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    color: white;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    margin-bottom: 1rem;
}

.convert-btn:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

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

/* Output Wrapper */
.output-wrapper {
    position: relative;
}

.output-wrapper textarea {
    padding-right: 5rem;
}

/* Copy Button */
.copy-btn {
    position: absolute;
    right: 0.5rem;
    top: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.25rem;
    padding: 0.5rem 0.75rem;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
}

.copy-btn:hover {
    color: var(--primary-color);
    border-color: var(--primary-color);
    background: var(--primary-light);
}

.copy-btn.copied {
    color: var(--success-color);
    border-color: var(--success-color);
}

/* All Results */
.all-results {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-top: 0.5rem;
}

.result-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    background: var(--bg-color);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.result-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    min-width: 100px;
}

.result-value {
    flex: 1;
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 0.9rem;
    color: var(--text-primary);
    word-break: break-all;
}

.copy-small-btn {
    flex-shrink: 0;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-light);
    cursor: pointer;
    transition: var(--transition);
}

.copy-small-btn:hover {
    color: var(--primary-color);
    border-color: var(--primary-color);
}

.copy-small-btn.copied {
    color: var(--success-color);
    border-color: var(--success-color);
}

/* Options Row */
.options-row {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.checkbox-label input[type="checkbox"] {
    width: 18px;
    height: 18px;
    accent-color: var(--primary-color);
    cursor: pointer;
}

/* Toast */
.toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    padding: 0.75rem 1.5rem;
    background: var(--text-primary);
    color: white;
    font-size: 0.9rem;
    font-weight: 500;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    transition: all 0.3s ease;
    pointer-events: none;
    z-index: 1000;
}

.toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 1rem;
    margin-top: 2rem;
    border-top: 1px solid var(--border-color);
}

footer p {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

footer a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}

/* Error State */
.error {
    border-color: var(--error-color) !important;
}

.error-message {
    color: var(--error-color);
    font-size: 0.875rem;
    margin-top: 0.25rem;
}

/* Responsive Design */
@media (max-width: 640px) {
    .container {
        padding: 1rem;
    }

    header h1 {
        font-size: 1.75rem;
    }

    header .subtitle {
        font-size: 0.95rem;
    }

    .converter-card {
        padding: 1rem;
    }

    .select-row {
        flex-direction: column;
        align-items: stretch;
    }

    .swap-btn {
        width: 100%;
        margin: 0;
    }

    .result-item {
        flex-wrap: wrap;
    }

    .result-label {
        min-width: auto;
        width: 100%;
    }

    .result-value {
        width: 100%;
        padding-right: 2.5rem;
    }

    .copy-small-btn {
        position: absolute;
        right: 0.75rem;
    }

    .result-item {
        position: relative;
    }

    .options-row {
        flex-direction: column;
        gap: 0.75rem;
    }

    .copy-btn span {
        display: none;
    }

    .copy-btn {
        padding: 0.5rem;
    }
}

@media (max-width: 400px) {
    header h1 {
        font-size: 1.5rem;
    }

    .convert-btn {
        padding: 0.75rem 1rem;
    }
}

/* Print Styles */
@media print {
    .copy-btn,
    .copy-small-btn,
    .swap-btn,
    .convert-btn {
        display: none;
    }

    .container {
        max-width: none;
    }

    .converter-card {
        box-shadow: none;
        border: 1px solid #ccc;
    }
}

/* Focus Visible */
button:focus-visible,
select:focus-visible,
input:focus-visible,
textarea:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-light);
}