:root {
    /* Color System */
    --primary-gradient: linear-gradient(135deg, #25D366 0%, #128C7E 100%);
    --primary-color: #128C7E;
    --error-color: #FF4B4B;
    --success-color: #22C55E;
    --text-color: #1A1A1A;
    --text-secondary: #666666;
    --bg-color: #F8FAFC;
    --card-bg: rgba(255, 255, 255, 0.85);
    --border-color: rgba(226, 232, 240, 0.5);
    --theme-toggle-bg: rgba(0, 0, 0, 0.05);

    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);

    /* Animation */
    --transition-base: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-smooth: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --text-color: #F1F5F9;
    --text-secondary: #94A3B8;
    --bg-color: #0F172A;
    --card-bg: rgba(30, 41, 59, 0.85);
    --border-color: rgba(51, 65, 85, 0.5);
    --theme-toggle-bg: rgba(255, 255, 255, 0.05);
    --error-color: #F87171;
    --success-color: #34D399;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 1.5rem;
    line-height: 1.6;
    transition: var(--transition-base);
    background-image: 
        radial-gradient(circle at 10% 20%, rgba(37, 211, 102, 0.1) 0%, transparent 20%),
        radial-gradient(circle at 90% 80%, rgba(18, 140, 126, 0.1) 0%, transparent 20%);
    background-attachment: fixed;
}

.layout {
    display: flex;
    gap: 1.5rem;
    max-width: 800px;
    margin: 0 auto;
    width: 100%;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.container, .recent-numbers-container {
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-radius: 24px;
    box-shadow: var(--shadow-lg);
    position: relative;
    border: 1px solid var(--border-color);
    transition: transform var(--transition-smooth), box-shadow var(--transition-smooth);
    width: 400px;
    max-width: 100%;
}

.container {
    background-color: var(--card-bg);
    padding: 2.5rem;
    display: flex;
    flex-direction: column;
}

.container:hover, .recent-numbers-container:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.12);
}

.recent-numbers-container {
    background-color: var(--card-bg);
    padding: 1.5rem;
    margin-top: 1.5rem;
}

.logo-container {
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: 2rem;
}

h1 {
    font-size: 1.875rem;
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    text-align: center;
    letter-spacing: -0.025em;
    line-height: 1.2;
}

.recent-numbers-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.recent-numbers-title .title-text {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.clear-history {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--error-color);
    padding: 0.5rem 0.75rem;
    border-radius: 8px;
    font-size: 0.75rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.375rem;
    transition: var(--transition-base);
}

.clear-history:hover {
    background: var(--theme-toggle-bg);
    transform: translateY(-1px);
}

.input-group {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
    justify-content: center;
}

.country-code {
    width: 85px !important;
    flex-shrink: 0;
}

.phone-number {
    width: 220px !important;
}

input {
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: 12px;
    font-size: 1rem;
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--text-color);
    transition: var(--transition-base);
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
}

input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(18, 140, 126, 0.15);
}

.error-text {
    font-size: 0.875rem;
    margin: 0.25rem 0 1rem;
    color: var(--error-color);
    text-align: left;
    min-height: 1.25rem;
    padding-left: calc(85px + 0.75rem);
}

.message-container {
    margin-bottom: 1rem;
}

textarea {
    width: 100%;
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: 12px;
    font-size: 1rem;
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--text-color);
    transition: var(--transition-base);
    resize: vertical;
    min-height: 60px;
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
}

textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(18, 140, 126, 0.15);
}

.recent-numbers {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.recent-number {
    padding: 0.75rem;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    font-size: 0.875rem;
    color: var(--text-color);
    cursor: pointer;
    transition: var(--transition-base);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    width: 100%;
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
}

.recent-number:hover {
    border-color: var(--primary-color);
    transform: translateY(-1px);
    background: rgba(255, 255, 255, 0.1);
}

.theme-toggle {
    position: absolute;
    top: 1.25rem;
    right: 1.25rem;
    padding: 0.75rem;
    border-radius: 12px;
    background: var(--theme-toggle-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    cursor: pointer;
    transition: var(--transition-base);
    display: flex;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
}

.theme-toggle:hover {
    transform: translateY(-1px);
    background: var(--theme-toggle-bg);
}

.send-btn {
    width: 100%;
    padding: 1rem;
    background: var(--primary-gradient);
    color: white;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transition: var(--transition-smooth);
    position: relative;
    overflow: hidden;
}

.send-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.send-btn:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

footer {
    margin-top: 2rem;
    text-align: center;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

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

footer a::after {
    content: '';
    position: absolute;
    width: 100%;
    height: 1px;
    bottom: -1px;
    left: 0;
    background-color: var(--primary-color);
    transform: scaleX(0);
    transform-origin: bottom right;
    transition: transform 0.3s ease;
}

footer a:hover::after {
    transform: scaleX(1);
    transform-origin: bottom left;
}

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

.loading-spinner {
    animation: spin 1s linear infinite;
}

.message {
    font-size: 0.875rem;
    padding: 0.75rem;
    border-radius: 8px;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    opacity: 0;
    transition: var(--transition-base);
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
}

.message.show {
    opacity: 1;
}

.message.success {
    background: rgba(34, 197, 94, 0.1);
    color: var(--success-color);
    border: 1px solid var(--success-color);
}

.message.error {
    background: rgba(255, 75, 75, 0.1);
    color: var(--error-color);
    border: 1px solid var(--error-color);
}

.confirmation-dialog {
    display: none;
    align-items: center;
    gap: 0.5rem;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--error-color);
    border-radius: 8px;
    padding: 0.75rem;
    margin-bottom: 1rem;
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
}

.confirmation-dialog.show {
    display: flex;
}

.confirmation-dialog .actions {
    margin-left: auto;
    display: flex;
    gap: 0.5rem;
}

.confirmation-dialog button {
    padding: 0.25rem 0.5rem;
    font-size: 0.75rem;
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition-base);
}

.confirmation-dialog .confirm-yes {
    background: var(--error-color);
    color: white;
    border: none;
}

.confirmation-dialog .confirm-no {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-color);
}

/* Responsive design */
@media (max-width: 768px) {
    .layout {
        flex-direction: column;
    }

    .container, .recent-numbers-container {
        max-width: 100%;
        width: 100%;
        flex: none;
    }

    .recent-numbers-container {
        margin-top: 1.5rem;
        position: static;
    }
}

@media (max-width: 480px) {
    body {
        padding: 1rem;
    }

    .container, .recent-numbers-container {
        padding: 1.5rem;
        border-radius: 16px;
    }

    h1 {
        font-size: 1.5rem;
    }

    .error-text {
        padding-left: 0;
        text-align: center;
    }

    input {
        padding: 0.75rem;
    }
}