/* ============================
   DESIGN SYSTEM & VARIABLES
   ============================ */

:root {
    --color-bg: #f9fafb;
    --color-card: #ffffff;
    --color-primary: #2563eb;
    --color-text: #111827;
    --color-subtext: #6b7280;
    --color-border: #e5e7eb;
    
    --spacing-section: 60px;
    --spacing-card: 16px;
    --spacing-gap: 16px;
    --radius: 10px;
    
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

/* ============================
   RESET & GLOBAL STYLES
   ============================ */

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    font-size: 16px;
}

/* ============================
   TYPOGRAPHY
   ============================ */

h1 {
    font-size: 3rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--spacing-gap);
}

h2 {
    font-size: 2rem;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: var(--spacing-gap);
}

h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-gap);
}

p {
    font-size: 1rem;
    font-weight: 400;
    margin-bottom: var(--spacing-gap);
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.2s ease;
}

a:hover {
    color: #60a5fa;
}

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

.header {
    position: sticky;
    top: 0;
    z-index: 100;
    height: 56px;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    display: flex;
    align-items: center;
}

.header-container {
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-nav {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav-link {
    font-size: 0.95rem;
    color: var(--color-subtext);
    transition: color 0.2s ease;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-primary);
}

.about-nav-bold {
    font-weight: 700;
}

.nav-btn {
    padding: 8px 16px;
    background-color: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--radius);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

.nav-btn:hover {
    background-color: #1d4ed8;
}

/* ============================
   HERO SECTION
   ============================ */

.hero {
    padding: 40px 32px 24px;
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 240px;
}

.hero-content {
    max-width: 700px;
}

.hero-title {
    color: var(--color-text);
    font-size: 2.25rem;
}

.hero-subtitle {
    font-size: 1.1rem;
    color: var(--color-subtext);
    margin-bottom: 20px;
}

.cta-button {
    padding: 10px 24px;
    background-color: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--radius);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s ease;
    height: 40px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.cta-button:hover {
    background-color: #1d4ed8;
}

.about-hero {
    min-height: 280px;
}

/* ============================
   TOOLS SECTION
   ============================ */

.tools-section {
    padding: 24px 32px 40px;
    background-color: var(--color-bg);
}

.tools-container {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

.tool-card {
    background-color: var(--color-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: var(--spacing-card);
    display: flex;
    flex-direction: column;
}

.tool-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-gap);
}

/* ============================
   UPLOAD BOX
   ============================ */

.upload-box {
    border: 2px dashed var(--color-border);
    border-radius: var(--radius);
    padding: 20px 16px;
    text-align: center;
    cursor: pointer;
    transition: border-color 0.2s ease, background-color 0.2s ease;
    margin-bottom: 12px;
    min-height: 120px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.upload-box:hover {
    border-color: var(--color-primary);
    background-color: rgba(37, 99, 235, 0.03);
}

.upload-icon {
    width: 40px;
    height: 40px;
    color: var(--color-primary);
    margin-bottom: 8px;
    stroke: currentColor;
}

.upload-text {
    font-size: 0.95rem;
    font-weight: 500;
    margin-bottom: 4px;
}

.upload-hint {
    font-size: 0.8rem;
    color: var(--color-subtext);
    margin: 0;
}

.file-info {
    background-color: rgba(37, 99, 235, 0.08);
    border: 1px solid var(--color-primary);
    border-radius: var(--radius);
    padding: 12px;
    margin-bottom: 16px;
}

.file-name {
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: 4px;
}

.file-size {
    font-size: 0.875rem;
    color: var(--color-subtext);
    margin: 0;
}

/* ============================
   INPUT GROUPS
   ============================ */

.input-group {
    margin-bottom: 16px;
}

.input-label {
    display: block;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: 6px;
}

.input-row {
    display: flex;
    gap: var(--spacing-gap);
}

.input-field {
    flex: 1;
    padding: 10px;
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    color: var(--color-text);
    font-size: 0.95rem;
    font-family: var(--font-family);
    transition: border-color 0.2s ease;
}

.input-field:focus {
    outline: none;
    border-color: var(--color-primary);
}

.input-select {
    width: 100px;
}

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

.compress-btn {
    width: 100%;
    padding: 10px;
    background-color: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--radius);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s ease;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-top: auto;
}

.compress-btn:hover:not(:disabled) {
    background-color: #1d4ed8;
}

.compress-btn:disabled {
    background-color: var(--color-border);
    cursor: not-allowed;
}

.btn-primary {
    padding: 10px 20px;
    background-color: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--radius);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s ease;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-primary:hover {
    background-color: #1d4ed8;
}

.btn-secondary {
    padding: 10px 20px;
    background-color: transparent;
    color: var(--color-primary);
    border: 1px solid var(--color-primary);
    border-radius: var(--radius);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-secondary:hover {
    background-color: rgba(37, 99, 235, 0.08);
}

/* ============================
   LOADING STATE
   ============================ */

.loading {
    text-align: center;
    padding: 20px 0;
}

.spinner {
    width: 32px;
    height: 32px;
    border: 3px solid var(--color-border);
    border-top: 3px solid var(--color-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 12px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.loading p {
    color: var(--color-subtext);
    font-size: 0.95rem;
    margin: 0;
}

/* ============================
   RESULT SECTION
   ============================ */

.result-section {
    padding: 40px 32px;
}

.result-card {
    max-width: 700px;
    margin: 0 auto;
    background-color: var(--color-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 28px;
}

.result-title {
    text-align: center;
    margin-bottom: 32px;
}

.result-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-bottom: 20px;
}

.stat-item {
    padding: 12px;
    background-color: rgba(37, 99, 235, 0.05);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    text-align: center;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--color-subtext);
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-primary);
    margin: 0;
}

.stat-value.reduction {
    color: #10b981;
}

.result-message {
    text-align: center;
    color: var(--color-subtext);
    margin-bottom: 20px;
}

.result-actions {
    display: flex;
    gap: 12px;
}

.result-actions button {
    flex: 1;
}

/* ============================
   AD PLACEHOLDERS
   ============================ */

.ad-container {
    margin: 16px 0;
    padding: 8px 0;
    text-align: center;
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
    min-height: 90px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.ad-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--color-card);
    border: 1px dashed var(--color-border);
    color: var(--color-subtext);
    font-size: 0.875rem;
}

.ad-top {
    height: 80px;
    margin: 0 32px 24px;
    border-radius: var(--radius);
    max-width: calc(100% - 64px);
    margin-left: auto;
    margin-right: auto;
}

.ad-inline {
    height: 200px;
    margin: 24px 32px;
    border-radius: var(--radius);
    max-width: calc(100% - 64px);
    margin-left: auto;
    margin-right: auto;
}

.ad-bottom {
    height: 80px;
    margin: 24px 32px 0;
    border-radius: var(--radius);
    max-width: calc(100% - 64px);
    margin-left: auto;
    margin-right: auto;
}

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

.footer {
    background-color: var(--color-card);
    border-top: 1px solid var(--color-border);
    padding: 32px;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-content {
    flex: 1;
}

.copyright {
    font-size: 0.875rem;
    color: var(--color-subtext);
    margin: 0;
}

.footer-nav {
    display: flex;
    gap: 32px;
}

.footer-link {
    font-size: 0.95rem;
    color: var(--color-subtext);
    transition: color 0.2s ease;
}

.footer-link:hover {
    color: var(--color-primary);
}

/* ============================
   ABOUT PAGE
   ============================ */

.about-section {
    padding: 40px 32px;
}

.about-container {
    max-width: 900px;
    margin: 0 auto;
}

.about-content {
    margin-bottom: 80px;
}

.section-title {
    font-size: 1.75rem;
    font-weight: 700;
    margin: 32px 0 16px 0;
}

.section-title:first-child {
    margin-top: 0;
}

.section-text {
    color: var(--color-subtext);
    line-height: 1.8;
}

.feature-list {
    list-style: none;
    margin-bottom: var(--spacing-gap);
}

.feature-list li {
    padding: 12px 0;
    color: var(--color-subtext);
    line-height: 1.8;
}

.feature-list strong {
    color: var(--color-text);
}

/* ============================
   DEVELOPER SECTION
   ============================ */

.developer-section {
    background-color: var(--color-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 28px;
}

.developer-card {
    min-height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.developer-info {
    text-align: center;
}

.developer-name {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 12px;
}

.developer-bio {
    font-size: 1rem;
    color: var(--color-subtext);
    margin-bottom: 12px;
    line-height: 1.6;
}

.developer-background {
    font-size: 0.95rem;
    color: var(--color-subtext);
    margin-bottom: 20px;
}

.developer-link {
    display: inline-block;
    padding: 8px 16px;
    background-color: var(--color-primary);
    color: white;
    border-radius: var(--radius);
    font-weight: 600;
    transition: background-color 0.2s ease;
}

.developer-link:hover {
    background-color: #1d4ed8;
}

/* ============================
   LOGO STYLING
   ============================ */

.header-logo {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--color-text);
    letter-spacing: -0.5px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.logo-icon {
    width: 24px;
    height: 24px;
    color: var(--color-primary);
    flex-shrink: 0;
}

.logo-icon svg {
    width: 100%;
    height: 100%;
    stroke: currentColor;
}

.logo-text {
    display: flex;
    gap: 0;
    align-items: baseline;
}

.logo-text-black {
    color: var(--color-text);
    font-weight: 700;
}

.logo-text-blue {
    color: var(--color-primary);
    font-weight: 700;
    font-size: 0.95rem;
}

/* ============================
   MODAL STYLING
   ============================ */

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
}

.modal-card {
    position: relative;
    z-index: 1001;
    background-color: var(--color-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    max-width: 500px;
    width: 90%;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    animation: slideIn 0.2s ease-out;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 24px;
    border-bottom: 1px solid var(--color-border);
}

.modal-header h2 {
    margin: 0;
    font-size: 1.25rem;
    color: var(--color-text);
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--color-subtext);
    cursor: pointer;
    padding: 0;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    transition: background-color 0.2s ease;
}

.modal-close:hover {
    background-color: var(--color-bg);
}

.modal-body {
    padding: 20px 24px;
    color: var(--color-subtext);
    line-height: 1.6;
}

.modal-body p {
    margin: 0;
    font-size: 1rem;
}

.modal-footer {
    padding: 16px 24px;
    border-top: 1px solid var(--color-border);
    display: flex;
    justify-content: flex-end;
    gap: 12px;
}

.btn-modal-primary {
    padding: 10px 24px;
    background-color: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--radius);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s ease;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-modal-primary:hover {
    background-color: #1d4ed8;
}

/* ============================
   WHY CHOOSE US SECTION
   ============================ */

.why-choose-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
    margin: 32px 0;
}

.why-choose-item {
    padding: 20px;
    background-color: var(--color-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    text-align: center;
    transition: all 0.2s ease;
}

.why-choose-item:hover {
    border-color: var(--color-primary);
    box-shadow: 0 2px 8px rgba(37, 99, 235, 0.1);
}

.why-choose-icon {
    width: 50px;
    height: 50px;
    margin: 0 auto 12px;
    color: var(--color-primary);
}

.why-choose-icon svg {
    width: 100%;
    height: 100%;
    stroke: currentColor;
}

.why-choose-item h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin: 0 0 8px 0;
    color: var(--color-text);
}

.why-choose-item p {
    font-size: 0.95rem;
    color: var(--color-subtext);
    margin: 0;
    line-height: 1.5;
}

/* ============================
   RESPONSIVE DESIGN
   ============================ */

@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }

    h2 {
        font-size: 1.5rem;
    }

    .header-container {
        padding: 0 20px;
    }

    .header-nav {
        gap: 16px;
    }

    .nav-btn {
        padding: 6px 12px;
        font-size: 0.8rem;
    }

    .hero {
        padding: 40px 20px;
        min-height: auto;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .tools-section {
        padding: 40px 20px;
    }

    .tools-container {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .upload-box {
        padding: 20px 12px;
    }

    .result-stats {
        grid-template-columns: 1fr;
        gap: 12px;
    }

    .ad-placeholder {
        margin-left: 20px;
        margin-right: 20px;
        max-width: calc(100% - 40px);
    }

    .footer-container {
        flex-direction: column;
        gap: 20px;
    }

    .footer-nav {
        justify-content: center;
    }

    .about-container {
        padding: 0 20px;
    }

    .why-choose-grid {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .developer-section {
        padding: 20px;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 1.5rem;
    }

    h2 {
        font-size: 1.25rem;
    }

    .header-container {
        padding: 0 16px;
    }

    .header-nav {
        gap: 12px;
    }

    .nav-btn {
        padding: 6px 12px;
        font-size: 0.75rem;
    }

    .tools-container {
        gap: 16px;
    }

    .tool-card {
        padding: 16px;
    }

    .input-row {
        flex-direction: column;
    }

    .input-select {
        width: 100%;
    }

    .result-actions {
        flex-direction: column;
    }

    .result-actions button {
        width: 100%;
    }
}